Posts Tagged ‘running’

Deny DHCP Address by MAC on Linux

Thursday, October 8th, 2020

Deny DHCP addresses by MAC ignore MAC to not be DHCPD leased on GNU / Linux howto

I have not blogged for a long time due to being on a few weeks vacation and being in home with a small cute baby. However as a hardcore and a bit of dumb System administrator, I have spend some of my vacation and   worked on bringing up the the www.pc-freak.net and the other Websites hosted as a high availvailability ones living on a 2 Webservers running on a Master to Master MySQL Replication backend database, this is oll hosted on  servers, set to run as a round robin DNS hosts on 2 servers one old Lenove ThinkCentre Edge71 as well as a brand new real Lenovo server Lenovo ThinkServer SD350 with 24 CPUs and a 32 GB of RAM
To assure Internet Connectivity is having a good degree of connectivity and ensure websites hosted on both machines is not going to die if one of the 2 pair configured Fiber Optics Internet Providers Bergon.NET has some Issues, I've rented another Internet Provider Line is set bought from the VIVACOM Mobile Fiber Internet provider – that is a 1 Gigabit Fiber Optics Line.
Next to that to guarantee there is no Database, Webserver, MailServer, Memcached and other running services did not hit downtimes due to Electricity power outage, two Powerful Uninterruptable Power Supplies (UPS)  FPS Fortron devices are connected to the servers each of which that could keep the machine and the connected switches and Servers for up to 1 Hour.

The machines are configured to use dhcpd to distributed IP addresses and the Main Node is set to distribute IPs, however as there is a local LAN network with more of a personal Work PCs, Wireless Devices and Testing Computers and few Virtual machines in the Network and the IPs are being distributed in a consequential manner via a ISC DHCP server.

As always to make everything work properly hence, I had again some a bit weird non-standard requirement to make some of the computers within the Network with Static IP addresses and the others to have their IPs received via the DHCP (Dynamic Host Configuration Protocol) and add some filter for some of the Machine MAC Addresses which are configured to have a static IP addresses to prevent the DHCP (daemon) server to automatically reassign IPs to this machines.

After a bit of googling and pondering I've done it and some of the machines, therefore to save others the efforts to look around How to set Certain Computers / Servers Network Card MAC (Interfaces) MAC Addresses  configured on the LAN network to use Static IPs and instruct the DHCP server to ingnore any broadcast IP addresses leases – if they're to be destined to a set of IGNORED MAcs, I came up with this small article.

Here is the DHCP server /etc/dhcpd/dhcpd.conf from my Debian GNU / Linux (Buster) 10.4

 

option domain-name "pcfreak.lan";
option domain-name-servers 8.8.8.8, 8.8.4.4, 208.67.222.222, 208.67.220.220;
max-lease-time 891200;
authoritative;
class "black-hole" {
    match substring (hardware, 1, 6);
    ignore booting;
}
subclass "black-hole" 18:45:91:c3:d9:00;
subclass "black-hole" 70:e2:81:13:44:11;
subclass "black-hole" 70:e2:81:13:44:12;
subclass "black-hole" 00:16:3f:53:5d:11;
subclass "black-hole" 18:45:9b:c6:d9:00;
subclass "black-hole" 16:45:93:c3:d9:09;
subclass "black-hole" 16:45:94:c3:d9:0d;/etc/dhcpd/dhcpd.conf
subclass "black-hole" 60:67:21:3c:20:ec;
subclass "black-hole" 60:67:20:5c:20:ed;
subclass "black-hole" 00:16:3e:0f:48:04;
subclass "black-hole" 00:16:3e:3a:f4:fc;
subclass "black-hole" 50:d4:f5:13:e8:ba;
subclass "black-hole" 50:d4:f5:13:e8:bb;
subnet 192.168.0.0 netmask 255.255.255.0 {
        option routers                  192.168.0.1;
        option subnet-mask              255.255.255.0;
}
host think-server {
        hardware ethernet 70:e2:85:13:44:12;
        fixed-address 192.168.0.200;
}
default-lease-time 691200;
max-lease-time 891200;
log-facility local7;

To spend you copy paste efforts a file with Deny DHCP Address by Mac Linux configuration is here
/home/hipo/info
Of course I have dumped the MAC Addresses to omit a data leaking but I guess the idea behind the MAC ADDR ignore is quite clear

The main configuration doing the trick to ignore a certain MAC ALenovo ThinkServer SD350ddresses that are reachable on the Connected hardware switch on the device is like so:

class "black-hole" {
    match substring (hardware, 1, 6);
    ignore booting;
}
subclass "black-hole" 18:45:91:c3:d9:00;


The Deny DHCP Address by MAC is described on isc.org distribution lists here but it seems the documentation on the topic on how to Deny / IGNORE DHCP Addresses by MAC Address on Linux has been quite obscure and limited online.

As you can see in above config the time via which an IP is freed up and a new IP lease is done from the server is severely maximized as often DHCP servers do use a max-lease-time like 1 hour (3600) seconds:, the reason for increasing the lease time to be to like 10 days time is that the IPs in my network change very rarely so it is a waste of CPU cycles to do a frequent lease.

default-lease-time 691200;
max-lease-time 891200;


As you see to Guarantee resolving works always as expected I have configured – Google Public DNS and OpenDNS IPs

option domain-name-servers 8.8.8.8, 8.8.4.4, 208.67.222.222, 208.67.220.220;


One hint to make is, after setting up all my desired config in the standard config location /etc/dhcp/dhcpd.conf it is always good idea to test configuration before reloading the running dhcpd process.

 

root@pcfreak: ~# /usr/sbin/dhcpd -t
Internet Systems Consortium DHCP Server 4.4.1
Copyright 2004-2018 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Config file: /etc/dhcp/dhcpd.conf
Database file: /va/home/hipo/infor/lib/dhcp/dhcpd.leases
PID file: /var/run/dhcpd.pid
 

That's all folks with this sample config the IPs under subclass "black-hole", which are a local LAN Static IP Addresses will never be offered leasess anymore from the ISC DHCP.
Hope this stuff helps someone, enjoy and in case if you need a colocation of a server or a website hosting for a really cheap price on this new set High Availlability up described machines open an inquiry on https://web.pc-freak.net.

 

Find when cron.daily cron.weekly and cron.monthly run on Redhat / CentOS / Debian Linux and systemd-timers

Wednesday, March 25th, 2020

Find-when-cron.daily-cron.monthly-cron.weekly-run-on-Redhat-CentOS-Debian-SuSE-SLES-Linux-cron-logo

 

The problem – Apache restart at random times


I've noticed today something that is occuring for quite some time but was out of my scope for quite long as I'm not directly involved in our Alert monitoring at my daily job as sys admin. Interestingly an Apache HTTPD webserver is triggering alarm twice a day for a short downtime that lasts for 9 seconds.

I've decided to investigate what is triggering WebServer restart in such random time and investigated on the system for any background running scripts as well as reviewed the system logs. As I couldn't find nothing there the only logical place to check was cron jobs.
The usual
 

crontab -u root -l


Had no configured cron jobbed scripts so I digged further to check whether there isn't cron jobs records for a script that is triggering the reload of Apache in /etc/crontab /var/spool/cron/root and /var/spool/cron/httpd.
Nothing was found there and hence as there was no anacron service running but /usr/sbin/crond the other expected place to look up for a trigger even was /etc/cron*

 

1. Configured default cron execution times, every day, every hour every month

 

# ls -ld /etc/cron.*
drwxr-xr-x 2 root root 4096 feb 27 10:54 /etc/cron.d/
drwxr-xr-x 2 root root 4096 dec 27 10:55 /etc/cron.daily/
drwxr-xr-x 2 root root 4096 dec  7 23:04 /etc/cron.hourly/
drwxr-xr-x 2 root root 4096 dec  7 23:04 /etc/cron.monthly/
drwxr-xr-x 2 root root 4096 dec  7 23:04 /etc/cron.weekly/

 

After a look up to each of above directories, finally I found the very expected logrorate shell script set to execute from /etc/cron.daily/logrotate and inside it I've found after the log files were set to be gzipped and moved to execute WebServer restart with:

systemctl reload httpd 

 

My first reaction was to ponder seriously why the script is invoking systemctl reload httpd instead of the good oldschool

apachectl -k graceful

 

But it seems on Redhat and CentOS since RHEL / CentOS version 6.X onwards systemctl reload httpd is supposed to be identical and a substitute for apachectl -k graceful.
Okay the craziness of innovation continued as obviously the reload was causing a Downtime to be visible in the Zabbix HTTPD port Monitoring graph …
Now as the problem was identified the other logical question poped up how to find out what is the exact timing scheduled to run the script in that unusual random times each time ??
 

2. Find out cron scripts timing Redhat / CentOS / Fedora / SLES

 

/etc/cron.{daily,monthly,weekly} placed scripts's execution method has changed over the years, causing a chaos just like many Linux standard things we know due to the inclusion of systemd and some other additional weird OS design changes. The result is the result explained above scripts are running at a strange unexpeted times … one thing that was intruduced was anacron – which is also executing commands periodically with a different preset frequency. However it is considered more thrustworhty by crond daemon, because anacron does not assume the machine is continuosly running and if the machine is down due to a shutdown or a failure (if it is a Virtual Machine) or simply a crond dies out, some cronjob necessery for overall set environment or application might not run, what anacron guarantees is even though that and even if crond is in unworking defunct state, the preset scheduled scripts will still be served.
anacron's default file location is in /etc/anacrontab.

A standard /etc/anacrontab looks like so:
 

[root@centos ~]:# cat /etc/anacrontab
# /etc/anacrontab: configuration file for anacron
 
# See anacron(8) and anacrontab(5) for details.
 
SHELL=/bin/sh
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
# the maximal random delay added to the base delay of the jobs
RANDOM_DELAY=45
# the jobs will be started during the following hours only
START_HOURS_RANGE=3-22
 
#period in days   delay in minutes   job-identifier   command
1    5    cron.daily        nice run-parts /etc/cron.daily
7    25    cron.weekly        nice run-parts /etc/cron.weekly
@monthly 45    cron.monthly        nice run-parts /etc/cron.monthly

 

START_HOURS_RANGE : The START_HOURS_RANGE variable sets the time frame, when the job could started. 
The jobs will start during the 3-22 (3AM-10PM) hours only.

  • cron.daily will run at 3:05 (After Midnight) A.M. i.e. run once a day at 3:05AM.
  • cron.weekly will run at 3:25 AM i.e. run once a week at 3:25AM.
  • cron.monthly will run at 3:45 AM i.e. run once a month at 3:45AM.

If the RANDOM_DELAY env var. is set, a random value between 0 and RANDOM_DELAY minutes will be added to the start up delay of anacron served jobs. 
For instance RANDOM_DELAY equels 45 would therefore add, randomly, between 0 and 45 minutes to the user defined delay. 

Delay will be 5 minutes + RANDOM_DELAY for cron.daily for above cron.daily, cron.weekly, cron.monthly config records, i.e. 05:01 + 0-45 minutes

A full detailed explanation on automating system tasks on Redhat Enterprise Linux is worthy reading here.

!!! Note !!! that listed jobs will be running in queue. After one finish, then next will start.
 

3. SuSE Enterprise Linux cron jobs not running at desired times why?


in SuSE it is much more complicated to have a right timing for standard default cron jobs that comes preinstalled with a service 

In older SLES release /etc/crontab looked like so:

 

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
HOME=/

# run-parts
01 * * * * root run-parts /etc/cron.hourly
02 4 * * * root run-parts /etc/cron.daily
22 4 * * 0 root run-parts /etc/cron.weekly
42 4 1 * * root run-parts /etc/cron.monthly


As time of writting article it looks like:

 

SHELL=/bin/sh
PATH=/usr/bin:/usr/sbin:/sbin:/bin:/usr/lib/news/bin
MAILTO=root
#
# check scripts in cron.hourly, cron.daily, cron.weekly, and cron.monthly
#
-*/15 * * * *   root  test -x /usr/lib/cron/run-crons && /usr/lib/cron/run-crons >/dev/null 2>&1

 

 


This runs any scripts placed in /etc/cron.{hourly, daily, weekly, monthly} but it may not run them when you expect them to run. 
/usr/lib/cron/run-crons compares the current time to the /var/spool/cron/lastrun/cron.{time} file to determine if those jobs need to be run.

For hourly, it checks if the current time is greater than (or exactly) 60 minutes past the timestamp of the /var/spool/cron/lastrun/cron.hourly file.

For weekly, it checks if the current time is greater than (or exactly) 10080 minutes past the timestamp of the /var/spool/cron/lastrun/cron.weekly file.

Monthly uses a caclucation to check the time difference, but is the same type of check to see if it has been one month after the last run.

Daily has a couple variations available – By default it checks if it is more than or exactly 1440 minutes since lastrun.
If DAILY_TIME is set in the /etc/sysconfig/cron file (again a suse specific innovation), then that is the time (within 15minutes) when daily will run.

For systems that are powered off at DAILY_TIME, daily tasks will run at the DAILY_TIME, unless it has been more than x days, if it is, they run at the next running of run-crons. (default 7days, can set shorter time in /etc/sysconfig/cron.)
Because of these changes, the first time you place a job in one of the /etc/cron.{time} directories, it will run the next time run-crons runs, which is at every 15mins (xx:00, xx:15, xx:30, xx:45) and that time will be the lastrun, and become the normal schedule for future runs. Note that there is the potential that your schedules will begin drift by 15minute increments.

As you see this is very complicated stuff and since God is in the simplicity it is much better to just not use /etc/cron.* for whatever scripts and manually schedule each of the system cron jobs and custom scripts with cron at specific times.


4. Debian Linux time start schedule for cron.daily / cron.monthly / cron.weekly timing

As the last many years many of the servers I've managed were running Debian GNU / Linux, my first place to check was /etc/crontab which is the standard cronjobs file that is setting the { daily , monthly , weekly crons } 

 

 debian:~# ls -ld /etc/cron.*
drwxr-xr-x 2 root root 4096 фев 27 10:54 /etc/cron.d/
drwxr-xr-x 2 root root 4096 фев 27 10:55 /etc/cron.daily/
drwxr-xr-x 2 root root 4096 дек  7 23:04 /etc/cron.hourly/
drwxr-xr-x 2 root root 4096 дек  7 23:04 /etc/cron.monthly/
drwxr-xr-x 2 root root 4096 дек  7 23:04 /etc/cron.weekly/

 

debian:~# cat /etc/crontab 
# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin# Example of job definition:
# .—————- minute (0 – 59)
# |  .————- hour (0 – 23)
# |  |  .———- day of month (1 – 31)
# |  |  |  .——- month (1 – 12) OR jan,feb,mar,apr …
# |  |  |  |  .—- day of week (0 – 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name command to be executed
17 *    * * *    root    cd / && run-parts –report /etc/cron.hourly
25 6    * * *    root    test -x /usr/sbin/anacron || ( cd / && run-parts –report /etc/cron.daily )
47 6    * * 7    root    test -x /usr/sbin/anacron || ( cd / && run-parts –report /etc/cron.weekly )
52 6    1 * *    root    test -x /usr/sbin/anacron || ( cd / && run-parts –report /etc/cron.monthly )

What above does is:

– Run cron.hourly once at every hour at 1:17 am
– Run cron.daily once at every day at 6:25 am.
– Run cron.weekly once at every day at 6:47 am.
– Run cron.monthly once at every day at 6:42 am.

As you can see if anacron is present on the system it is run via it otherwise it is run via run-parts binary command which is reading and executing one by one all scripts insude /etc/cron.hourly, /etc/cron.weekly , /etc/cron.mothly

anacron – few more words

Anacron is the canonical way to run at least the jobs from /etc/cron.{daily,weekly,monthly) after startup, even when their execution was missed because the system was not running at the given time. Anacron does not handle any cron jobs from /etc/cron.d, so any package that wants its /etc/cron.d cronjob being executed by anacron needs to take special measures.

If anacron is installed, regular processing of the /etc/cron.d{daily,weekly,monthly} is omitted by code in /etc/crontab but handled by anacron via /etc/anacrontab. Anacron's execution of these job lists has changed multiple times in the past:

debian:~# cat /etc/anacrontab 
# /etc/anacrontab: configuration file for anacron

# See anacron(8) and anacrontab(5) for details.

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
HOME=/root
LOGNAME=root

# These replace cron's entries
1    5    cron.daily    run-parts –report /etc/cron.daily
7    10    cron.weekly    run-parts –report /etc/cron.weekly
@monthly    15    cron.monthly    run-parts –report /etc/cron.monthly

In wheezy and earlier, anacron is executed via init script on startup and via /etc/cron.d at 07:30. This causes the jobs to be run in order, if scheduled, beginning at 07:35. If the system is rebooted between midnight and 07:35, the jobs run after five minutes of uptime.
In stretch, anacron is executed via a systemd timer every hour, including the night hours. This causes the jobs to be run in order, if scheduled, beween midnight and 01:00, which is a significant change to the previous behavior.
In buster, anacron is executed via a systemd timer every hour with the exception of midnight to 07:00 where anacron is not invoked. This brings back a bit of the old timing, with the jobs to be run in order, if scheduled, beween 07:00 and 08:00. Since anacron is also invoked once at system startup, a reboot between midnight and 08:00 also causes the jobs to be scheduled after five minutes of uptime.
anacron also didn't have an upstream release in nearly two decades and is also currently orphaned in Debian.

As of 2019-07 (right after buster's release) it is planned to have cron and anacron replaced by cronie.

cronie – Cronie was forked by Red Hat from ISC Cron 4.1 in 2007, is the default cron implementation in Fedora and Red Hat Enterprise Linux at least since Version 6. cronie seems to have an acive upstream, but is currently missing some of the things that Debian has added to vixie cron over the years. With the finishing of cron's conversion to quilt (3.0), effort can begin to add the Debian extensions to Vixie cron to cronie.

Because cronie doesn't have all the Debian extensions yet, it is not yet suitable as a cron replacement, so it is not in Debian.
 

5. systemd-timers – The new crazy systemd stuff for script system job scheduling


Timers are systemd unit files with a suffix of .timer. systemd-timers was introduced with systemd so older Linux OS-es does not have it.
 Timers are like other unit configuration files and are loaded from the same paths but include a [Timer] section which defines when and how the timer activates. Timers are defined as one of two types:

 

  • Realtime timers (a.k.a. wallclock timers) activate on a calendar event, the same way that cronjobs do. The option OnCalendar= is used to define them.
  • Monotonic timers activate after a time span relative to a varying starting point. They stop if the computer is temporarily suspended or shut down. There are number of different monotonic timers but all have the form: OnTypeSec=. Common monotonic timers include OnBootSec and OnActiveSec.

     

     

    For each .timer file, a matching .service file exists (e.g. foo.timer and foo.service). The .timer file activates and controls the .service file. The .service does not require an [Install] section as it is the timer units that are enabled. If necessary, it is possible to control a differently-named unit using the Unit= option in the timer’s [Timer] section.

    systemd-timers is a complex stuff and I'll not get into much details but the idea was to give awareness of its existence for more info check its manual man systemd.timer

Its most basic use is to list all configured systemd.timers, below is from my home Debian laptop
 

debian:~# systemctl list-timers –all
NEXT                         LEFT         LAST                         PASSED       UNIT                         ACTIVATES
Tue 2020-03-24 23:33:58 EET  18s left     Tue 2020-03-24 23:31:28 EET  2min 11s ago laptop-mode.timer            lmt-poll.service
Tue 2020-03-24 23:39:00 EET  5min left    Tue 2020-03-24 23:09:01 EET  24min ago    phpsessionclean.timer        phpsessionclean.service
Wed 2020-03-25 00:00:00 EET  26min left   Tue 2020-03-24 00:00:01 EET  23h ago      logrotate.timer              logrotate.service
Wed 2020-03-25 00:00:00 EET  26min left   Tue 2020-03-24 00:00:01 EET  23h ago      man-db.timer                 man-db.service
Wed 2020-03-25 02:38:42 EET  3h 5min left Tue 2020-03-24 13:02:01 EET  10h ago      apt-daily.timer              apt-daily.service
Wed 2020-03-25 06:13:02 EET  6h left      Tue 2020-03-24 08:48:20 EET  14h ago      apt-daily-upgrade.timer      apt-daily-upgrade.service
Wed 2020-03-25 07:31:57 EET  7h left      Tue 2020-03-24 23:30:28 EET  3min 11s ago anacron.timer                anacron.service
Wed 2020-03-25 17:56:01 EET  18h left     Tue 2020-03-24 17:56:01 EET  5h 37min ago systemd-tmpfiles-clean.timer systemd-tmpfiles-clean.service

 

8 timers listed.


N ! B! If a timer gets out of sync, it may help to delete its stamp-* file in /var/lib/systemd/timers (or ~/.local/share/systemd/ in case of user timers). These are zero length files which mark the last time each timer was run. If deleted, they will be reconstructed on the next start of their timer.

Summary

In this article, I've shortly explain logic behind debugging weird restart events etc. of Linux configured services such as Apache due to configured scripts set to run with a predefined scheduled job timing. I shortly explained on how to figure out why the preset default install configured cron jobs such as logrorate – the service that is doing system logs archiving and nulling run at a certain time. I shortly explained the mechanism behind cron.{daily, monthy, weekly} and its execution via anacron – runner program similar to crond that never misses to run a scheduled job even if a system downtime occurs due to a crashed Docker container etc. run-parts command's use was shortly explained. A short look at systemd.timers was made which is now essential part of almost every new Linux release and often used by system scripts for scheduling time based maintainance tasks.

Rsync copy files with root privileges between servers with root superuser account disabled

Tuesday, December 3rd, 2019

 

rsync-copy-files-between-two-servers-with-root-privileges-with-root-superuser-account-disabled

Sometimes on servers that follow high security standards in companies following PCI Security (Payment Card Data Security) standards it is necessery to have a very weird configurations on servers,to be able to do trivial things such as syncing files between servers with root privileges in a weird manners.This is the case for example if due to security policies you have disabled root user logins via ssh server and you still need to synchronize files in directories such as lets say /etc , /usr/local/etc/ /var/ with root:root user and group belongings.

Disabling root user logins in sshd is controlled by a variable in /etc/ssh/sshd_config that on most default Linux OS
installations is switched on, e.g. 

grep -i permitrootlogin /etc/ssh/sshd_config
PermitRootLogin yes


Many corporations use Vulnerability Scanners such as Qualys are always having in their list of remote server scan for SSH Port 22 to turn have the PermitRootLogin stopped with:

 

PermitRootLogin no


In this article, I'll explain a scenario where we have synchronization between 2 or more servers Server A / Server B, whatever number of servers that have already turned off this value, but still need to
synchronize traditionally owned and allowed to write directories only by root superuser, here is 4 easy steps to acheive it.

 

1. Add rsyncuser to Source Server (Server A) and Destination (Server B)


a. Execute on Src Host:

 

groupadd rsyncuser
useradd -g 1000 -c 'Rsync user to sync files as root src_host' -d /home/rsyncuser -m rsyncuser

 

b. Execute on Dst Host:

 

groupadd rsyncuser
useradd -g 1000 -c 'Rsync user to sync files dst_host' -d /home/rsyncuser -m rsyncuser

 

2. Generate RSA SSH Key pair to be used for passwordless authentication


a. On Src Host
 

su – rsyncuser

ssh-keygen -t rsa -b 4096

 

b. Check .ssh/ generated key pairs and make sure the directory content look like.

 

[rsyncuser@src-host .ssh]$ cd ~/.ssh/;  ls -1

id_rsa
id_rsa.pub
known_hosts


 

3. Copy id_rsa.pub to Destination host server under authorized_keys

 

scp ~/.ssh/id_rsa.pub  rsyncuser@dst-host:~/.ssh/authorized_keys

 

Next fix permissions of authorized_keys file for rsyncuser as anyone who have access to that file (that exists as a user account) on the system
could steal the key and use it to run rsync commands and overwrite remotely files, like overwrite /etc/passwd /etc/shadow files with his custom crafted credentials
and hence hack you 🙂
 

Hence, On Destionation Host Server B fix permissions with:
 

su – rsyncuser; chmod 0600 ~/.ssh/authorized_keys
[rsyncuser@dst-host ~]$

 

For improved security here to restrict rsyncuser to be able to run only specific command such as very specific script instead of being able to run any command it is good to use little known command= option
once creating the authorized_keys

 

4. Test ssh passwordless authentication works correctly


For that Run as a normal ssh from rsyncuser

On Src Host

 

[rsyncuser@src-host ~]$ ssh rsyncuser@dst-host


Perhaps here is time that for those who, think enabling a passwordless authentication is not enough secure and prefer to authorize rsyncuser via a password red from a secured file take a look in my prior article how to login to remote server with password provided from command line as a script argument / Running same commands on many servers 

5. Enable rsync in sudoers to be able to execute as root superuser (copy files as root)

 


For this step you will need to have sudo package installed on the Linux server.

Then, Execute once logged in as root on Destionation Server (Server B)

 

[root@dst-host ~]# grep 'rsyncuser ALL' /etc/sudoers|wc -l || echo ‘rsyncuser ALL=NOPASSWD:/usr/bin/rsync’ >> /etc/sudoers
 

 

Note that using rsync with a ALL=NOPASSWD in /etc/sudoers could pose a high security risk for the system as anyone authorized to run as rsyncuser is able to overwrite and
respectivle nullify important files on Destionation Host Server B and hence easily mess the system, even shell script bugs could produce a mess, thus perhaps a better solution to the problem
to copy files with root privileges with the root account disabled is to rsync as normal user somewhere on Dst_host and use some kind of additional script running on Dst_host via lets say cron job and
will copy gently files on selective basis.

Perhaps, even a better solution would be if instead of granting ALL=NOPASSWD:/usr/bin/rsync in /etc/sudoers is to do ALL=NOPASSWD:/usr/local/bin/some_copy_script.sh
that will get triggered, once the files are copied with a regular rsyncuser acct.

 

6. Test rsync passwordless authentication copy with superuser works


Do some simple copy, lets say copy files on Encrypted tunnel configurations located under some directory in /etc/stunnel on Server A to /etc/stunnel on Server B

The general command to test is like so:
 

rsync -aPz -e 'ssh' '–rsync-path=sudo rsync' /var/log rsyncuser@$dst_host:/root/tmp/


This will copy /var/log files to /root/tmp, you will get a success messages for the copy and the files will be at destination folder if succesful.

 

On Src_Host run:

 

[rsyncuser@src-host ~]$ dst=FQDN-DST-HOST; user=rsyncuser; src_dir=/etc/stunnel; dst_dir=/root/tmp;  rsync -aP -e 'ssh' '–rsync-path=sudo rsync' $src_dir  $rsyncuser@$dst:$dst_dir;

 

7. Copying files with root credentials via script


The simlest file to use to copy a bunch of predefined files  is best to be handled by some shell script, the most simple version of it, could look something like this.
 

#!/bin/bash
# On server1 use something like this
# On server2 dst server
# add in /etc/sudoers
# rsyncuser ALL=NOPASSWD:/usr/bin/rsync

user='rsyncuser';

dst_dir="/root/tmp";
dst_host='$dst_host';
src[1]="/etc/hosts.deny";
src[2]="/etc/sysctl.conf";
src[3]="/etc/samhainrc";
src[4]="/etc/pki/tls/";
src[5]="/usr/local/bin/";

 

for i in $(echo ${src[@]}); do
rsync -aPvz –delete –dry-run -e 'ssh' '–rsync-path=sudo rsync' "$i" $rsyncuser@$dst_host:$dst_dir"$i";
done


In above script as you can see, we define a bunch of files that will be copied in bash array and then run a loop to take each of them and copy to testination dir.
A very sample version of the script rsync_with_superuser-while-root_account_prohibited.sh 
 

Conclusion


Lets do short overview on what we have done here. First Created rsyncuser on SRC Server A and DST Server B, set up the key pair on both copied the keys to make passwordless login possible,
set-up rsync to be able to write as root on Dst_Host / testing all the setup and pinpointing a small script that can be used as a backbone to develop something more complex
to sync backups or keep system configurations identicatial – for example if you have doubts that some user might by mistake change a config etc.
In short it was pointed the security downsides of using rsync NOPASSWD via /etc/sudoers and few ideas given that could be used to work on if you target even higher
PCI standards.

 

Qmail redirect mail to another one and keep local Mailbox copy with .qmail file – Easy Set up email forwarding Qmail

Saturday, August 11th, 2018

Qmail redirect mail box to another one with .Qmail file dolphin artistic logo

QMail (Considered to be the most secure Mail server out there whose modified version is running on Google – Gmail.com and Mail Yahoo! and Yandex EMail (SMTP) servers, nowadays has been highly neglected and considered obsolete thus most people prefer to use postfix SMTP or EXIM but still if you happen to be running a number of qmail old rack Mail servers (running a bunch of Email addresses and Virtual Domains straight on the filesystem – very handy by the way for administration much better than when you have a Qmail Mail server configured to store its Mailboxes within MySQL / PostgreSQL or other Database server – because simple vpopmail configured to play nice with Qmail and store all user emails directly on Filesystem (though considered more insecure the email correspondence can be easily red, if the server is hacked it is much better managable for a small and mid-sized mailserver) or have inherited them from another sys admin and you wonder how to redirect a single Mailbox:

(under domain lets say domain's email  my-server1.com should forward to to SMTP domain my-server-whatever2.com (e.g. your-email-username@server-whatever1.com is supposed to forward to your-email-username2@server-whatever2.com).
To achieve it create new file called .qmail

Under the Qmail or VirtualDomain location for example:

/var/qmail/mailnames/myserver1.com/username/.qmail

 

e.g
 

root@qmail-server:~# vim /var/qmail/mailnames/myserver1.com/your-email-username/.qmail
&your-email-username@server-whatever1.com

your-email-username@example1.com
/home/vpopmail/domains/server-whatever2.com/your-email-username/Maildir/


!!! NOTE N.B. !!! the last slash / after Maildir (…Maildir/) is important to be there otherwise mail will not get delivered
That's all now send a test email, just to make sure redirection works properly, assuming the .qmail file is created by root, by default the file permissions will be with privileges root:root.

Note
 

That shouldn't be a problem at all. That's all now enjoy emails being dropped out to the second mail 🙂

 

Share SCREEN terminal session in Linux / Screen share between two or more users howto

Wednesday, October 11th, 2017

share-screen-terminal-session-in-linux-share-linux-unix-shell-between-two-or-more-users

 

1. Short Intro to Screen command and what is Shared Screen Session

Do you have friends who want to learn some GNU / Linux or BSD basics remotely? Do you have people willing to share a terminal session together for educational purposes within a different network? Do you just want to have some fun and show off yourself between two or more users?

If the answer to the questions is yes, then continue on reading, otherwise if you're already aware how this is being done, just ignore this article and do something more joyful.

So let me start.

Some long time ago when I was starting to be a Free Software user and dedicated enthusiast, I've been given by a friend an interesting freeshell hosting access and I stumbled upon / observed an interesting phenomenon, multiple users like 5 or 10 were connected simultaneously to the same shell sharing their command line.

I can't remember what kind of shell I happen to be sharing with the other logged in users with the same account, was that bash / csh / zsh or another one but it doesn't matter, it was really cool to find out multiple users could be standing together on GNU / Linux and *BSD with the same account and use the regular shell for chatting or teaching each others  new Linux / Unix commands e.g. being able to type in shell simultaneously.

The multiple shared shell session was possible thanks to the screen command

For those who hear about screen for a first time, here is the package description:

 

# apt-cache show screen|grep -i desc -A 1
Description-en: terminal multiplexer with VT100/ANSI terminal emulation
 GNU Screen is a terminal multiplexer that runs several separate "screens" on

Description-md5: 2d86b86ed6058a04c540802e49312f40
Homepage: https://savannah.gnu.org/projects/screen
root@jericho:/usr/local/src/pure-python-otr# apt-cache show screen|grep -i desc -A 2
Description-en: terminal multiplexer with VT100/ANSI terminal emulation
 GNU Screen is a terminal multiplexer that runs several separate "screens" on
 a single physical character-based terminal. Each virtual terminal emulates a


Description-md5: 2d86b86ed6058a04c540802e49312f40
Homepage: https://savannah.gnu.org/projects/screen
Tag: hardware::input:keyboard, implemented-in::c, interface::text-mode,


There is plenty of things to use screen for as it provides you a way to open Virtual Terminals into a single ssh or physical console TTY login session and I've been in love with screen command since day 1 I found out about it.

To start using screen just invoke it into a shell and enter a screen command combinations that make various stuff for you.

 

2. Some of the most useful Daily Screen Key Combinations for the Sys Admin


To do use the various screen options, use the escape sequence (CTRL + Some Word), following by the command. For a full list of all of the available commands, run man screen, however
for the sake of interest below short listing shows some of most useful screen key combination invoked commands:

 

 

Ctrl-a a Passes a Ctrl-a through to the terminal session running within screen.
Ctrl-a c Create a new Virtual shell screen session within screen
Ctrl-a d Detaches from a screen session.
Ctrl-a f Toggle flow control mode (enable/disable Ctrl-Q and Ctrl-S pass through).
Ctrl-a k Detaches from and kills (terminates) the screen session.
Ctrl-a q Passes a Ctrl-q through to the terminal session running within screen (or use Ctrl-a f to toggle whether screen captures flow control characters).
Ctrl-a s Passes a Ctrl-s through to the terminal session running within screen (or use Ctrl-a f to toggle whether screen captures flow control characters).
Ctrl-a :kill Also detaches from and kills (terminates) the screen session.
Ctrl-a :multiuser on Make the screen session a multi-user session (so other users can attach).
Ctrl-a :acladd USER Allow the user specified (USER) to connect to a multi-user screen session.
Ctrl-a p Move around multiple opened Virtual terminals in screen (Move to previous)
Ctrl-a n Move backwards in multiple opened screen sessions under single shell connection


I have to underline strongly for me personally, I'm using the most

 

CTRL + A + D (to detach session),

CTRL + A + C to open new session within screen (I tend to open multiple sessions for multiple ssh connections with this),

CTRL + A + P, CTRL +  A + N – I use this twoto move around all my open screen Virtual sessions.
 

3. HOW TO ACTUALLY SHARE TERMINAL SESSION BETWEEN MULTIPLE USERS?


3.1 Configuring Shared Sessions so other users can connect

You need to  have a single user account on a Linux or Unix like server lets say that might be the /etc/passwd, /etc/shadow, /etc/group account screen and you have to give the password to all users to be participating into the shared screen shell session.

E.g. create new system account screen

root@jericho:~# adduser screen
Adding user `screen' …
Adding new group `screen' (1001) …
Adding new user `screen' (1001) with group `screen' …
The home directory `/home/screen' already exists.  Not copying from `/etc/skel'.
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Changing the user information for screen
Enter the new value, or press ENTER for the default
    Full Name []: Screen user to give users shared access to /bin/bash
    Room Number []:
    Work Phone []:
    Home Phone []:
    Other []:
Is the information correct? [Y/n] Y

Now distribute the user / pass pair around all users who are to be sharing the same virtual bash session via screen and instruct each of them to run:

hipo@jericho:~$  screen -d -m -S shared-session
hipo@jericho:~$

hipo@jericho:~$ screen -list

There is a screen on:
    4095.shared-session    (10.10.2017 20:22:22)    (Detached)
1 Socket in /run/screen/S-hipo.


3.2. Attaching to just created session
 

Simply login with as many users you need with SSH to the remote server and instruct them to run the following command to re-attach to the just created new session by you:

hipo@jericho:~$ screeen -x

That's all folks now everyone can type in simultaneously and enjoy the joys of the screen shared session.

If for some reasons more than one session is created by the simultaneously logged in users either as an exercise or by mistake i.e.:

hipo@jericho:~$ screen -list

There are screens on:
    4880.screen-session    (10.10.2017 20:30:09)    (Detached)
    4865.another-session    (10.10.2017 20:29:58)    (Detached)
    4847.hey-man    (10.10.2017 20:29:49)    (Detached)
    4831.another-session1    (10.10.2017 20:29:45)    (Detached)
4 Sockets in /run/screen/S-hipo.

You have to instruct everyone to connect actually to the exact session we need, as screen -x will ask them to what session they like to connect.

In that case to connect to screen-session, each user has to run with their account:

hipo@jericho:~$ screen -x shared-session


If under some circumstances it happened that there is more than one opened shared screen virtual session, for example screen -list returns:

 

hipo@jericho:~$ screen -list
There are screens on:
    5065.screen-session    (10.10.2017 20:33:20)    (Detached)
    4095.screen-session    (10.10.2017 20:30:08)    (Detached)

All users have to connect to the exact screen-session created name and ID, like so:

hipo@jericho:~$ screen -x 4095.screen-session
 


Here is the meaning of used options

 

-d option instructs screen to detach,
-m makes it multiuser session so other users can attach
-S argument is just to give the screen session a name
-list Sesssion gives the screen-session ID

Once you're over with screen session (e.g. all users that are learning and you show them stuff and ask them to test by themselves and have completed, scheduled tasks), to kill it just press CTRL + A + K
 

4. Share screen /bin/bash shell session with another user

Sharing screen session between different users is even more useful to the shared session of one user as you might have a *nix server with many users who might attach to your opened session directly, instead of being beforehand instructed to connect with a single user.

That's perfect also for educational purposes if you want to learn some Linux to a class of people, as you can use their ordinary accounts and show them stuff on a Linux / BSD  machine.

Assuming that you follow and created already screen-session with screen cmd

hipo@jericho:~$ screen -list
There is a screen on:
        5560.screen-session      (10.10.2017 20:41:06)   (Multi, attached)
1 Socket in /run/screen/S-hipo.

hipo@jericho:~$

Next attach to the session

bunny@jericho:~$ screen -r shared-session
bunny@jericho:~$ Ctrl-a :multiuser on
bunny@jericho:~$ Ctrl-a :acladd user2
bunny@jericho:~$ screen -x UserNameHere/shared-session
 

Here are 2 screenshots on what should happen if you had done above command combinations correctly:

screen-share-session-to-multi-users-screenshot-multiuser-on-on-gnome-terminal2

screen-share-session-to-multi-users-screenshot-multiuser-on-on-gnome-terminal3

In order to be able to share screen Virtual terminal ( VTY ) sessions between separate (different) logged in users, you have to have screen command be suid (SUID bit for screen is disabled in most Linux distributions for security reasons).

Without making SUID the screen binary file, you are to get the error:

hipo@jericho:/home/hipo$ screen -x hipo/shared

Must run suid root for multiuser support.

If you are absolutely sure you know what you're doing here is how to make screen command sticky bit:

 

root@jericho:/home/hipo# which screen
root@jericho:/home/hipo# /usr/bin/screen
root@jericho:/home/hipo# root@jericho:/home/hipo# root@jericho:/home/hipo# chmod u+s $(which screen)
chmod 755 /var/run/screen
root@jericho:/home/hipo# rm -fr /var/run/screen/*
exit

Play Midis on Linux / Make Linux MIDI Ready for the Future – Enable embedded MIDI music to play in a Browser, Play MIDIs with VLC and howto enjoy Midis in Text Console

Wednesday, October 4th, 2017

how-to-play-midi-on-gnu-linux-in-graphic-environment-console-and-browser-midi-synthesizer-and-linux-tux-together

 

Play Midis on Linux or Make Linux MIDI Ready for the Future – Enable embedded MIDI music to play in a Browser, Play MIDIs with VLC and howto enjoy Midis in Text Console HOWTO

 

Playing MIDI has been quite a lot of fun historically,

if you grow up in the days when personal computers were still young and the Sound Blaster was a luxury, before the raise of Mp3 music format, you have certainly enjoyed the beeping of PC Speaker and later on during 386 and 486 / 586 computers the enjoyment of playing tracked music such as S3M and MOD,

in that good days playing MIDI music was the only alternative for PC maniacs who doesn't own a CD Drive (which itself) was another luxury and even thouse who had a CD ROM device, were mainly playing music in CD audio format (.CDA).
Anyhow MIDI was a cheap and a CPU unintensive way to listen to equivalent of favourite popular Audio Songs and for those who still remember many of the songs were recreated in MIDI format, just with a number of synthesized instruments without any voice (as MIDI is usually).

The same was true also for the good old days of raise of Mobile Phones, when polyphonic was a standard as CPU power was low MIDI was a perfect substitute for the CPU heavy Encoded MP3s / OGG and other formats that required a modern for that time Intel CPU running in 50+ Mhz usually 100 / 166Mhz was perfect for the days to play Mp3 but still even on that PCs we listened to Midi songs.

Therefore if you're one of those people like me who still enjoy to play some Midi Music in the year 2017 and feel a bit like Back into the Future movie and a Free Software fan and user, especially if you're a novice GNU  / Linux Free Software user, you will be unpleasently surprised that most today's default Linux distributions doesn't have an easy way to play Midi music format out of the box right after install.

Hence below article aims to give you an understanding on

How you can play Midi Music on GNU / Linux Operating System

First, lets Prepare to load necessery Linux kernel modules to make sure MIDI can be played by soundcard:

In /etc/modules make sure you have the following list of modules loaded:
 

linux-desktop:~# cat /etc/modules
3c59x
snd-emu10k1
snd-pcm-oss
snd-mixer-oss
snd-seq-oss

!Note the modules are working as of time of writting and in time can change to some other modules, depending on how the development of ALSA (Advanced Linux Sound Architecture) goes, and if the developers decide to rename the upmentioned modules

If you just have added the modules to /etc/modules with vim / nano to reload modules into the Linux kernel run:

 

linux-desktop:~# modprobe -a


Secondly, Installing a whole bunch of MIDI music related program tools can be achieved in Debian by installing the multimedia-midi package, e.g.:

 

linux-desktop:~# apt-get install –yes multimedia-midi

 

1. Playing Midi in Graphical environment with a double click using VLC


How to make MIDI easy listanable in Linux graphical environment like GNOME / KDE / XFCE desktop ?

 

If you want to make Midi music execution sa easy as  just clicking on the .MIDI file format on Linux you can do that with a midi extension available for VLC (Video Lan Client) Universal Multi Platform Media Player player

To install it on Debian Ubuntu GNU / Linux
 

# apt-get install –yes vlc-plugin-fluidsynth

 

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Изт:1 http://deb.debian.org/debian stretch/main amd64 vlc-plugin-fluidsynth amd64 2.2.6-1~deb9u1 [6754 B]
Изтеглени 6754 B за 0с (33,6 kB/сек)           
Selecting previously unselected package vlc-plugin-fluidsynth:amd64.
(Reading database … 382976 files and directories currently installed.)
Preparing to unpack …/vlc-plugin-fluidsynth_2.2.6-1~deb9u1_amd64.deb …
Unpacking vlc-plugin-fluidsynth:amd64 (2.2.6-1~deb9u1) …
Setting up vlc-plugin-fluidsynth:amd64 (2.2.6-1~deb9u1) …
Processing triggers for libvlc-bin:amd64 (2.2.6-1~deb9u1) …


Besides making your MIDI play on the GUI environment easy as a a point and click VLC will also be able to play MIDIs on GNU / Linux from your favourite browser (nomatter Firefox / Chrome or Opera), even though the player would play in a new PopUP Window it is easy to select once MIDI file from a random website for example – here is a directory listing of Webserver with Doom II Soundtrack in MIDI format , click over any file from list and Choose option for VLC to always remember that MIDI files has to be opened with VLC player.
 


2. Enable Firefox / IceWeasel browser to Support Website embedded MIDI files

 

 

So VLC could make you listen the downloadable MIDIs from Web pages but,
 

What if you have stumbled on an old website which was configured with very OLD HTML Code to play some nice music (or even different MIDI songs) for each part of the website (for each webpage) and you want to have the Websites created with embedded MIDIs to automatically play on Linux oncce you visit the site?


Sadly default support in Browser for MIDI across all GNU / Linux, I've used so far never worked out of the box, not that still anyone is developing modern websites with MIDIs, but still for the sake of backward compitability and for sake of interactivity it is worthy to enable embedded MIDI support in Linux

But with a couple of tunings as usual GNU / Linux can do almost everything, so here is how to enable embedded browser support for Midi on Linux (That should work with minor modifications not only on Debian / Ubuntu / ArchLinux but also on Fedoras, CentOS etc.
If you try it on any of this distributions, please drop a short comment and tell me in few lines how you made embedded midi worked on that distros.

 

apt-get install –yes timidity mozplugger

Next do restart firefox

Sometimes in order to work you might need to delete /home/[YOUR_USERNAME]/.mozilla/pluginreg.dat and restart firefox again, e.g. make a backup and give it a try:

 

cp -rpf /home/hipo/.mozilla/pluginreg.dat /home/hipo/.mozilla/pluginreg.dat.bak
rm -f /home/hipo/.mozilla/pluginreg.dat

 

Another good tip as talking for embedding MIDI support is to embed XPDF to render PDF pages inside the Browser, by default this is done by GNOME's Evince PDF reader but as it is sometimes buggy and might crash it is generally a good idea to switch to xpdf instead, if for some reason PDF is not directly displaying in browser or suddenly stopped working after some distro uipgrade, you might want to do below as well:
 

apt-get install xpdf

vim /etc/mozpluggerrc

Fin d and Comment out the line starting with:

It should look like this afterwards:

 Repeat Swallow ….
 

text/x-pdf: pdf: PDF file
#      repeat swallow(documentShell) fill: acroread -geometry +9000+9000 +useFrontEndProgram "$file"
        repeat noisy swallow(Xpdf) fill: xpdf -g +9000+9000 "$file"
        repeat noisy swallow(gv) fill: gv –safer –quiet –antialias -geometry +9000+9000 "$file"


 

3. Play Midi music in Linux text console / terminal


There is a console tool that historically has been like the Linux standard for playing midis over the years as I remember, its called timidity

 


To install timidity on .Deb based Linux:
 

linux-desktop:~$ su root
Password:
linux-desktop:~# apt-get install –yes timidity

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(Reading database … 382981 files and directories currently installed.)
Preparing to unpack …/timidity_2.13.2-40.5_amd64.deb …
Unpacking timidity (2.13.2-40.5) over (2.13.2-40.5) …
Processing triggers for menu (2.1.47+b1) …
Processing triggers for man-db (2.7.6.1-2) …
Setting up timidity (2.13.2-40.5) …
Processing triggers for menu (2.1.47+b1) …

 

To test your new MIDI Synthesizer tool and make the enjoyment full you can download Doom 2 extracted MIDI Soundtrack from here
 

Once you have downloaded above Metal MIDI DOOM old school arcade soundtrack and untarred it into your home directory be it ~/doom-midis

A remark to make here is timidity is quite CPU intensive, but on modern Dual and Quad-Core PC Notebooks, the CPU load is not of a big concern.

To test and play with timidity:
 

linux-desktop~$ timidity ~/mp3/midis/*


timidity-playing-doom-midi-bunny-song-on-debian-stretch-gnome-terminal-screenshot
 

hipo@jericho:~/mp3/midis$ aplaymidi -l
 Port    Client name                      Port name
 14:0    Midi Through                     Midi Through Port-0
128:0    TiMidity                         TiMidity port 0
128:1    TiMidity                         TiMidity port 1
128:2    TiMidity                         TiMidity port 2
128:3    TiMidity                         TiMidity port 3

 


We have also the playmidi  (simple midi text console terminal player), which historically was working quite decent and I use it to in the past on my RedHat 6.0 and RedHat 7.0 to listen to my .MID format files but unfortunately as of time of writting something is wrong with it, so when I try to play MIDIs with it instead of timidity I get this erro:

 

$ playmidi *.mid
Playmidi 2.4 Copyright (C) 1994-1997 Nathan I. Laredo, AWE32 by Takashi Iwai
This is free software with ABSOLUTELY NO WARRANTY.
For details please see the file COPYING.
open /dev/sequencer: No such file or directory

Even though I tried hard to resolve that error by loading various midi related MIDI modules and following a lot of the suggestions online on how to  make /dev/sequencer work again it was all no luck.
 

Some people back in the distant year 2005, reported the problem was solved by simply loading snd-seq

But as of time of writting:

 

# modprobe snd-seq

 

Some people said in archlinux's Forum

/dev/sequencer sequencer: No such file or directory

 

is solved by loading snd-seq-oss kernel module, but on my Debian Linux 9.1 Stretch, this ain't work as well :

 

root@jericho:/home/hipo/mp3/midis# modprobe snd-seq-oss
modprobe: FATAL: Module snd-seq-oss not found in directory /lib/modules/4.9.0-3-amd64
root@jericho:/home/hipo/mp3/midis# uname -a;
Linux jericho 4.9.0-3-amd64 #1 SMP Debian 4.9.30-2+deb9u5 (2017-09-19) x86_64 GNU/Linux


Another invention of mine was to try to also link /dev/snd/seq to /dev/sequencer but this produced no positive result either:

 

# ln -sf /dev/snd/seq /dev/sequencer
# ls -al /dev/sequencer
lrwxrwxrwx 1 root root 12 окт  4 16:48 /dev/sequencer -> /dev/snd/seq


Note that after lining in that way I got following error with my attempt to play MIDIs with playmidi

# playmidi *.mid
Playmidi 2.4 Copyright (C) 1994-1997 Nathan I. Laredo, AWE32 by Takashi Iwai
This is free software with ABSOLUTELY NO WARRANTY.
For details please see the file COPYING.
there is no soundcard


Anyhow on some other Linux distributions (especially with Older Kernel versions), some of the above 3 suggested Fix might work perfectly fine so if you have some time give it a try please and drop me  a comment on how it went, you will help the GNU / Linux community out there that way.

Well never mind the bollocks, so

Now back to where I started timidity even though it will play fine it will not give any indication on the lenght of the midi song (precious information such as how much time is left until the end is over).

Hence if you prefer a player that gives you an indicator on how much is left towards the end length of each of the played MIDI file you can give a try to wildmidi:

 

linux-desktop:~$ apt-cache show wildmidi|grep -i description -A 2

Description-en: software MIDI player
 Minimal MIDI player implementation based on the wildmidi library that
 can either dump to WAV or playback over ALSA. It is intended to

Description-md5: b4b34070ae88e73e3289b751230cfc89
Homepage: http://www.mindwerks.net/projects/wildmidi/
Tag: implemented-in::c, role::program, sound::midi, sound::player,

Description: software MIDI player
Description-md5: 4673a7051f104675c73eb344bb045607
Homepage: http://wildmidi.sourceforge.net/
Bugs: https://bugs.launchpad.net/ubuntu/+filebug


If yet not installed install it after becoming admin user:

 

linux-desktop:~$ su root
Password:

linux-desktop:~# apt-get install –yes wildmidi


wildmidi is much less CPU intensive (it uses gstreamer to play (Gstreamer – open source multimedia framework)

And next give it a try by running:

 

linux-desktop:~$ wildmidi ~/mp3/midis/*

 

wildmidi-midi-lenght-status-text-console-player-for-linux-ubuntu-debian-fedora-suse

 

 

4. Editting MIDI files with Free Software and Proprietary MIDI Editor Programs

 


If you want a professional software that can play Midi in a fuzzy interactive GUI way and have some extra possibilities to edit MIDIs and other format give a try to Muse Sequencer:
 

 

linux-desktop:~$ sudo apt-get install –yes muse

The following NEW packages will be installed:
  muse
0 upgraded, 1 newly installed, 0 to remove and 38 not upgraded.
Need to get 5814 kB of archives.
After this operation, 21.0 MB of additional disk space will be used.
Get:1 http://deb.debian.org/debian stretch/main amd64 muse amd64 2.1.2-3+b1 [5814 kB]
Fetched 5814 kB in 2s (2205 kB/s)                             
    are supported and installed on your system.
Preconfiguring packages …
Selecting previously unselected package muse.
(Reading database … 382981 files and directories currently installed.)
Preparing to unpack …/muse_2.1.2-3+b1_amd64.deb …
Unpacking muse (2.1.2-3+b1) …
Processing triggers for mime-support (3.60) …
Processing triggers for desktop-file-utils (0.23-1) …
Processing triggers for doc-base (0.10.7) …
Processing 1 added doc-base file…
Registering documents with scrollkeeper…
Processing triggers for man-db (2.7.6.1-2) …
Processing triggers for shared-mime-info (1.8-1) …
Unknown media type in type 'all/all'
Unknown media type in type 'all/allfiles'
Processing triggers for gnome-menus (3.13.3-9) …
Setting up muse (2.1.2-3+b1) …
Processing triggers for hicolor-icon-theme (0.15-1) …


 

Below is short description what Muse can do for you:

 

MusE is a MIDI/audio sequencer with recording and editing capabilities.
 Some Highlights:
 

  * Standard midifile (smf) import-/export.
  * Organizes songs in tracks and parts which you can arrange with
    the part editor.
  * MIDI editors: pianoroll, drum, list, controller.
  * Score editor with high quality postscript printer output.
  * Realtime: editing while playing.
  * Unlimited number of open editors.
  * Unlimited undo/redo.
  * Realtime and step-recording.
  * Multiple MIDI devices.
  * Unlimited number of tracks.
  * Sync to external devices: MTC/MMC, Midi Clock, Master/Slave.
  * Audio tracks, LADSPA host for master effects.
  * Multithreaded.
  * Uses raw MIDI devices.
  * XML project file.
  * Project file contains complete app state (session data).
  * Application spanning Cut/Paste Drag/Drop.

 

linux-desktop~:$ muse

muse-advanced-midi-editor-free-software-for-linux

 

Below is another non-free program that you might, try if MusE doesn't fit your needs (is not rich enough for editting capabilities is bitwig (though I don't recommend since it is not free software)

bitwig – Bitwig Studio is a multi-platform music-creation system for production, performance and DJing, with a focus on flexible editing tools and a super-fast workflow.
 


bitwig-midi-and-audio-non-free-software-advanced-useful-sound-editor-for-linx


 

5. Some examples for Text editing and MIDI Conversion to CSV and ABC file formats There is pretty much more

For the MIDI Extremists who or people that create MIDIs and want to learn how a MIDI is made (the content of it etc.), I suggest you take a look at these 3 command line MIDI editing / conversion tools
 

  • midi2abc – A little tool to create MIDI formats to ABC format
  • midi2csv – Conver tour Favourite MIDI files to CSV for educational purposes so see what Channels, Tracks and Time Intervals is a MIDI song mad
  • midicopy – Copy selected, track, channel, time interval of MIDI file to another MIDI file3

 

Well, that's all folks now enjoy your MIDIs and don't forget to donate, as I'm jobless at the moment and the only profit I make is just a few bucks out of advertisement on this blog.
 

Apache Webserver: How to Set up multile SSL certificates on multiple domains running on one IP address with Apache SNI feature

Wednesday, September 13th, 2017

apache-ssl-handshake-how-client-talks-to-server-illustrated

In the recent past it was impossible to add multiple different SSL .crt / .pem bundle certificates on Apache Webserver but each one of it was supposed to run under a separate domain or subdomain, preconfigured with a separate IP address, this has changed with the introduction of Apache SNI (Server Name Indication). What SNI does is it sends, the site visitor initiating connections on encrypted SSL port (443) or whatever configured a certificate that matches, the client requested server name.

Note that SNI is Apache HTTPD supported only and pitily can't be used on other services such as Mail Servers (SMTPS), (POP3S), (IMAPS) etc.
Older browsers did not have support for proper communication with WebServers supporting SNI communication, so for Websites whose aim is interoperatibility and large audience of Web clients still the preferrable way is to set up each VirtualHost under a separate IP, just like the good old days.

However Small and MidSized businesses could save some cash by not having to buy separate IPs for each Virtualhost, but just use SNI.
Besides that the people are relatively rarely using old browsers without SNI, so having clients with browsers not supporting SNI would certiainly be too rare. To recognize where a browser is having support for TLS or not is to check whether the Browser has support for TLS extension.

One requirement in order for SNI to work properly is to have registered domain because SNI works based on the requested ServerName by client.

On Debian GNU / Linux based distributions, you need to have Apache Webserver installed with enabled mod_ssl module:

 

linux:~# apt-get install –yes apache2

linux:~# a2enmod ssl

linux:~# /etc/init.d/apache2 restart


If you're not planning to get a trusted source certificate, especially if you're just a start-up business which is in process of testing the environment (you still did not ordered certificate via some domain registrar you might want to generate self signed certificate with openssl command and use that temporary:

 

linux:~# openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/apache2/ssl/your-domain.com/apache.key –out /etc/apache2/ssl/your-domain.com/apache.crt

Here among the prompted questions you need the a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank.
For some fields leave the default value,
If you enter '.', or press enter the field will be left blank.

—–
 

Country Name (2 letter code) [AU]:BG
State or Province Name (full name) [Some-State]: Sofia
Locality Name (eg, city) []:SOF
Organization Name (eg, company) [Internet Widgits Pty Ltd]:Pc-Freak.NET
Organizational Unit Name (eg, section) []:
Common Name (e.g. server FQDN or YOUR name) []:your-domain.com                
Email Address []:webmaster@your-domain.com

 


(by the way it might be interesting to mention here the list of cheapest domain name registrars on the Internet as of January 2017 – source site here

 

Below order is given as estimated by price /  quality and provided service approximate

 

1. BlueHost.com – Domains $6.95

2. NameCheap.Com – Annual fee $10.69

3. GoDaddy.com – Annual fee $8.99 for first year, $14.99$ for each additional year

4. HostGator.com – Annual fee $15.00

5. 1and1.com – Annual fee $0.99 for first year ($14.99 for each additional year)

6. Network Solutions – This was historically one of the first domain registrar companies, but the brand is pricy $34.99

7. Register.com – Not sure

8. Hostway.com – $9.95 (first year and $9.95 renewals)

9. Moniker.com – Annual fee $11.99

10. Netfirms.ca – Annual fee $9.95 first year, Renewal fee is $11.99 per year

 

Note that domain pricing could value depending on the type of domain name country extension and many of the domain registrars would give you discount if you purchase domain name / SSL for 2 / 3+ years.

sni-illustrated-how-it-works-how-to-configure-multiple-domains-ssl-on-same-ip-apache-webserver

Next step in order to use SNI is to configure the WebServer Virtualhosts file:

 

linux:~# vim /etc/apache2/sites-available/domain-names.com

 

# Instruct Apache to listen for connections on port 443
Listen 443
# Listen for virtual host requests on all IP addresses
NameVirtualHost *:443

# Go ahead and accept connections for these vhosts
# from non-SNI clients
SSLStrictSNIVHostCheck off

<VirtualHost *:80>
        ServerAdmin webmaster@your-domain.com
        ServerName your-domain.com
        DocumentRoot /var/www

# More directives comes here

</VirtualHost>


<VirtualHost *:443>

        ServerAdmin webmaster@localhost
        ServerName your-domain.com
        DocumentRoot /var/www

        #   SSL Engine Switch:
        #   Enable/Disable SSL for this virtual host.
        SSLEngine on

        #   A self-signed (snakeoil) certificate can be created by installing
        #   the ssl-cert package. See
        #   /usr/share/doc/apache2.2-common/README.Debian.gz for more info.
        #   If both key and certificate are stored in the same file, only the
        #   SSLCertificateFile directive is needed.
        SSLCertificateFile /etc/apache2/ssl/your-domain.com/apache.crt
        SSLCertificateKeyFile /etc/apache2/ssl/your-domain.com/apache.key

# More Apache directives could be inserted here
</VirtualHost>

 

<VirtualHost *:443>
  DocumentRoot /var/www/sites/your-domain2
  ServerName www.your-domain2.com

  # Other directives here

</VirtualHost>

Add as many of the SNI enabled VirtualHosts following the example below, or if you prefer seperate the vhosts into separate domains.

I also recommend to check out Apache's official documentation on SNI for NameBasedSSLVhostsWithSNI etc.


Hope this article was not too boring 🙂
Enjoy life

 

Enable printing from Windows and Macs remotely through Linux Print server – Share Brother Printer DCP-1610W with Linux CUPS and Samba Windows Share

Thursday, March 23rd, 2017

Brother-Printer-model-DCP-1610W-printer-scanner-and-copier-in-one-picture
I've recently bought a new Printer model Brother DCP 1610W and as in my home I have already a small Linux router and a web server where this blog and a couple of other websites runs and I need multiple PC / notebook / mobile phone enabled people to print on the Printer easily pretty much like a Printing server for a Small Office environment.

To do that of course I needed it configured to be accessible remotely for print via LAN and Wireless network. The task is not a complex one and printing remotely over the network is a standard thing many company organizations / universities and univerities does for quite some time and hence nowadays most printers are network connect ready so you just have to place them inside your home or corporate network and use the time to configure them via their web configuration interface or even some have their own embedded wifi adapter, as well as many printers nowdays can even be ready to print directly by just connecting the Printer to the Wi-Fi network and installing its drivers on a Win host.

Anyhow the most common way for both home printer configurations and corporate I'm aware of still is to Share the printer via Windows Server or Win Server Domain so anyone connected to the Network to be able to Add the printer via Winblows.

In the case i'm going to describe below my home the Wi-Fi router is connected to an 5 Port Network Switch (HUB) which on its hand is connected to the Linux router which serves multiple things (a Linux router, a hosting server (web server and a database server hosted, a mail server, traffic proxy server, a firewall and a NAT router), I decided to Share the printer to Wi-Fi connected and LAN clients directly switched via an UTP cable to the switch by using the good old Linux Samba Sharing server.

I did not actually do that for a really long time hence before I started I did some quick research to get an idea on the general steps to partake to succeed in Sharing the Printer over the network of this Debian's Wiki SystemPrinting Guide was mostly helpful.

 

1. Downloading and Installing necessery Brother Printer deb packages
 

A small remark to make here is my Linux server is running Debian GNU / Linux and hence this article is giving details on how Printer can be Shared on Debian though a minor adaptation of the article should make it possible to install also on any RHEL / CentOS / SuSE etc. Redhat based RPM Linux distribution.)

First step to do is to download Brother printer vendor provided drivers as of moment of writting this article they're here

To download the drivers get the proper links and use wget or curl to download all the necessery .deb archives in lets say in /root/brother-printer-drivers e.g. before that create the folder with:
 

root@linux:/root# mkdir /root/brother-printer-drivers

Also it might be helpful for those who need some other Brother Printer Linux driver complete list of Brother Printer all Linux drivers as of time of writting this post is found on this URL here

Next you need to install following Brother printer driver deb packages brscan-skey brscan4 dcp1610wcupswrapper dcp1610wlpr

root@linux:/root# cd brother-printer-drivers
root@linux:/root/brother-printer-drivers# dpkg -i –force-all brscan-skey-0.2.4-1.amd64.deb

root@linux:/root# dpkg -i –force-all brscan4-0.4.4-1.amd64.deb

root@linux:/root# dpkg -i –force-all dcp1610wcupswrapper-3.0.1-1.i386.deb

root@linux:/root# dpkg -i –force-all dcp1610wlpr-3.0.1-1.i386.deb

root@linux/root# cd  ../


Once installed dpkg -l should show like so:
 

root@linux:/root# dpkg -l |grep -i brother
ii  brscan-skey                                0.2.4-1                      Brother Linux scanner S-KEY tool
ii  brscan4                                    0.4.4-1                      Brother Scanner Driver
ii  dcp1610wcupswrapper                        3.0.1-1                      Brother DCP-1610W CUPS wrapper driver
ii  dcp1610wlpr                                3.0.1-1                      Brother DCP-1610W LPR driver

Brother's vendor provided packages will install drivers under /opt/brother
 

root@linux:/root# ls -al /opt/brother/
общо 16
drwxr-xr-x 4 root root 4096 яну 26 13:58 ./
drwxr-xr-x 3 root root 4096 яну 26 13:55 ../
drwxr-xr-x 3 root root 4096 яну 26 13:58 Printers/
drwxr-xr-x 4 root root 4096 яну 26 13:58 scanner/

 

2. Installing CUPS Printing Service and related Filters and Postscript packages necessery for PDF processing on CUPS server side

 

root@linux:/root#  apt-get install –yes cups cups-client cups-common cups-pdf cups-ppdc foomatic-db foomatic-db-engine foomatic-filters foomatic-filters-ppds openprinting-ppds lpr hp-ppd hpijs cups-pdf ghostscript-cups

Your printing should work normally without cups-pdf and ghostscript-cups packages installed but I install them just in case if PDF processing is problematic you can skip that.

It is also useful to install sane and sane-utils packages if you're going to use the brother's scanner capabilities.

root@linux:/root# apt-get install –yes sane sane-utils

Note that considering that all packages installed fine and the CUPS service is running, this should have set a proper printer into /etc/printcap a short database used to describe printers. printcap file is being used by UNIX's spooling system and allows you to dynamic addition and deletion of printers, for Linux / *Nix hosts which have more than one printer connected and added in CUPs records for the various printer goes there.
With a single Brother DCP-1610W Printer like my case is you should have records similar to these:

root@linux:~/brother-printer-drivers# cat /etc/printcap
DCP1610W:\
        :mx=0:\
        :sd=/var/spool/lpd/DCP1610W:\
        :sh:\
        :lp=/dev/usb/lp0:\
        :if=/opt/brother/Printers/DCP1610W/lpd/filter_DCP1610W:

 

 

3. Adding a Printer in CUPS the easy way through CUPS Printing System Web Interface

 

CUPS has a nice web interface for setting up and administering printers and print queues.

Below is a selfexplanatory screenshot of Add Printer screen 

add-a-new-printer-cups-web-admin-interface-screenshot-in-a-firefox-browser  .

 

Use your favourite browser (Firefox, Opera, Chromium, lynx, elinks – yes the great news is console / terminal browsers are also supported well by cups web iface) to display interface and add a printer via the Administration screen. If you are asked for a username and password see here.

cups-web-admin-interface-accessed-in-browser-listing-brother-dcp1610w-printer-screenshot

There are three sections. The first is for local printers; that is, printers which are usually attached to the machine you are using. These are very often printers using a USB connection but can be parallel or serial port printers.

Adding a USB printer is a common occurance and one should automatically be detected as a local printer and a URI (Unified Resource Indicator) for its connection displayed on the next page.
 

The Other Network Printers section requires you to specify the destination for the remote print queue/printer, which could be on the local network or many kilometres away. AppSocket is almost always available on a network printer and other devices and requires only the IP address of the printer and a port number. An Internet Printing Protocol (IPP) URI is the preferrred choice for connecting to another CUPS server because it is CUPS' native protocol. ipp14 is the ipp backend from CUPS 1.4 and Debian-specific. It is provided because some devices do not work with the current ipp backend, which has a stricter adherence to the IPP standard. A Line Printer Daemon (LPD) URI could be considered if the remote printing service does not support IPP satisfactorily or at all. As before, when a remote print queue is doing the filtering choose RAW as the Make/Manufacturer.

 

4. Printer Status and Control testing whether CUPS printing is up and running


 

Once cups is installed and hopefully up and running you should see the cups process up and running to check it do:

root@linux:/root# /etc/init.d/cups status; ps axuwwf|grep -i cups|grep -v grep
Status of Common Unix Printing System: cupsd is running.
root      2815  0.0  0.0  75364  2912 ?        Ss   Mar17   0:00 /usr/sbin/cupsd -C /etc/cups/cupsd.conf

To get some further testing you can also use lpstat command and should get ouput similar to belows:
 

root@linux:/root# lpstat -t
scheduler is running
no system default destination
device for DCP1610W: usb://Brother/DCP-1610W%20series
DCP1610W accepting requests since Fri Mar 17 23:03:37 2017
printer DCP1610W disabled since Fri Mar 17 23:03:37 2017 –
        Unplugged or turned off

At the moment of issuing above command it shows printer is disabled because of moment of execution the printer was turned off for a while cause I was not needing it you should get usually an output of enabled and ready to print.

lpstat is also about to report whether a queue is accepting jobs and what is yet to be printed you can do

 

 

5. Install and Configure Samba Sharing Server on the Linux server


 

You can setup CUPS to allow Windows machines to print to a CUPS server using an http address.

First, install the samba package. When you are asked to use WINS, say yes.

root@linux:/root#  apt-get install samba

Next you might want to set setup your /etc/cups/cupsd.conf file by default CUPS would listen to LPD's port 631 if you don't have a strong firewall isolating you from the Internet on port 631 you might want to change that port to another one lets say to Port 49651.


I personally prefer keep the default port 631 and do use a robust firewall. If you want to change it modify config to something like:

# Our private connection we listen to Listen *:49651 # Allow machines on local network to use printers <Location /printers> Order allow,deny Allow 192.168.0.* Allow 192.168.1.* </Location>

If you like to filter access to CUPs daemon to receive Printing requests to be originating only from the local network place in smb.conf also something with your private network ranges:

# Allow machines on local network to use printers

<Location /printers>
Order allow,deny
Allow 192.168.0.*
Allow 192.168.1.*
Allow 192.168.2.*
</Location>
<Location />
  # Allow remote administration…
  Order allow,deny
##  Allow all
Allow 192.168.0.*
Allow 192.168.1.*
Allow 192.168.2.*
</Location>
<Location />
  # Allow remote administration…
  Order allow,deny
##  Allow all
Allow 192.168.0.*
Allow 192.168.1.*
Allow 192.168.2.*
</Location>
<Location /admin>
  # Allow remote administration…
  Order allow,deny
##  Allow all
Allow 192.168.0.*
Allow 192.168.1.*
Allow 192.168.2.*
</Location>

 

This will listen on port 49651 from any network. You may use some other port number besides 631. Note that the dynamic and/or private ports as specified by the IANA are in the range 49152 through 65535. Also, this will only allow computers from the local network to print to the CUPS printers.
 

6. Use CUPS Printing server to print over the network directly

 

 

Next you need to restart the CUPS daemon once again as it will be used for samba printing
 


# service cups restart


Now on each Windows machine, Choose that you want to install a network printer and that you want to install a printer on the Internet or home/office network. The URL you will use should be smth like:
 


http://<cups_server_hostname>:49651/printers/DCP1610W

 

Lastly, select the Brother downloaded from Internet or the one that's available on the Install CD, for any other vendor printer if it is lets say HP Printer or Canon to install use the respective provided driver or as a last resort use the Generic section driver labeled MS Publisher Color Printer.

 

 

7. Configure Samba to Share CUPS network enabled printer


I've done a minor changes in default installed /etc/samba/smb.conf to make the printer accessible from The Samba server here is the main things to consider changing:
 

# Change this to the workgroup/NT-domain name your Samba server will part of
   workgroup = WORKGROUP

#   security = user
security = share

[printers]
   comment = PC Freak Printer
   browseable = yes
   path = /var/spool/samba
   printable = yes
   guest ok = yes
   read only = yes
   create mask = 0700

# Windows clients look for this share name as a source of downloadable
# printer drivers
[print$]
   comment = Printer Drivers
   path = /var/lib/samba/printers
   browseable = yes
   read only = yes
   guest ok = yes


Next restart Samba server to make the new setting take affect:
 

root@linux:/# /etc/init.d/samba restart
Stopping Samba daemons: nmbd smbd.
Starting Samba daemons: nmbd smbd.
root@linux:/# ps axu|grep -E "smb|nmb"
root     21887  0.0  0.0 169588  1904 ?        Ss   16:53   0:00 /usr/sbin/nmbd -D
root     21892  0.0  0.0 197560  3272 ?        Ss   16:53   0:00 /usr/sbin/smbd -D
root     21894  0.0  0.0 197560  1564 ?        S    16:53   0:00 /usr/sbin/smbd -D
root     21899  0.0  0.0 112368   840 pts/6    S+   16:53   0:00 grep -E smb|nmb

root@linux:/#

Complete current smb.conf configuration I use to make the Brother Printer DCP 1610W accesible via network share is here

This section needs updating as you can setup print server via samba print sharing just by uploading drivers.

When printing to windows printers in an NT domain using SMB the Device URI should use similar to:

 

smb://username:password@domain/server/printername

 

This allows Samba to authenticate against a domain controller for acces to the printer queue.

In my case as you can see in below smb.conf configuration I've configured Samba security = share which will allow anyone to access the samba server without authentication so you can omit  username:password@ part

One good way to determine the printername  (in case you are not sure of) is to use smbclient command line tool. computername refers to the name of the machine that shares the printer:

 

smbclient -L copmputername


computername is the name of the samba server machine or its IP address


E.g.
 

hipo@linux:~$ smbclient -L //192.168.0.1/
Enter Attitude's password:
Domain=[WORKGROUP] OS=[Unix] Server=[Samba 3.5.6]

        Sharename       Type      Comment
        ———       —-      ——-
        print$          Disk      Printer Drivers
        IPC$            IPC       IPC Service (pcfreak server)
        DCP1610W        Printer   DCP1610W
Domain=[WORKGROUP] OS=[Unix] Server=[Samba 3.5.6]

        Server               Comment
        ———            ——-
        PCFREAK              pcfreak server

        Workgroup            Master
        ———            ——-
        WORKGROUP            WORKGROUP


Check the ouput for entries of Type "Printer":


The resulting (Linux / Mac OS) Samba Share access URL from the output above would be

smb://192.168.0.1/DCP1610W


 

 

8. Adding Printer to your Windows machines to enable actual Remote Samba Sharing printing

Assuming you already know the Printer share name, here is what I needed to do to have the Printer Added on each of Windows Desktop PCs and Notebooks

 

Control Panel -> Devices and Printers -> Add a printer -> (Add a Network wireless or bluetooth printer)

Then instead of Searching the printer to click on:

The printer that I wasn't listed

add-samba-network-share-brother-dcp-1610w-printer-to-windows-7-machine-no-printer-found-from-add-printer

Then type in the URL or IP (as in my case) leading to the printer as you see in below screenshot:

 

9. Printer Samba Sharing Using Macintosh notebook as the Client and Debian as the Server

 

1. Assuming you have cups to set up the printer on Debian as described above.

2. On the Mac (OS X 10.4+) start Print and Fax from System Preferences. Use the + button to add a printer.

3. Look first in the "Default" tab. If the automagic printer-sharing has worked, and your Mac is connected to the local network properly, then the Debian-based printer should already be visible in the list.

Just select it and use the recommended print driver. If you face problems you can try to play with
Gutenprint Printer drivers to make it printing.

4. If your printer is not visible in the Default tab, then try adding it on the "IP" tab.

Pick IPP as the protocol, give the plain IP address of the server in the address box (in my case that's 192.168.0.1, and in the Queue box put
"printers/DCP1610W

Put whatever helps you identify the printer in the Name and Location boxes (fields), and choose a printer driver than matches Brother DCP1610W or with another printer installed whatever you used to set up the printer on Debian .
Finally Pray that God help you to make it work and press the Add button. If you prayed honestly and repenting for your sins perhaps you will have mercy and it will work, of course if not try to research online on how to fix it further by God's grace.

Note that making printing work on Mac is a little bit of tricky and it might cause you some extra effort / nerves to complete.

 

10. Some other Useful maintanance commands you might need in future CUPS Printer queue jobs maintance

 

For displaying or setting print queue options and defaults:

lpoptions -p <print_queue_name> -l

Stopping and starting print queues. Acceptance and rejection of jobs sent to a destination:
 

cupsdisable <print_queue_name>
cupsenable <print_queue_name>
cupsaccept <print_queue_name>
cupsreject <print_queue_name>


To Cancel all jobs on a destination and additionally delete job data files:

cancel -a <print_queue_name>
cancel -a -x <print_queue_name>

That's all folks, Thanks God the printer should be working. Enjoy!