Posts Tagged ‘fedora’

How to create user with only FTP access on Linux

Saturday, May 11th, 2013

Linux access only to ftp How to prohibit ssh access on GNU Linux

Creating user with access only through FTP is vital in daily routine system administration job. The reason why it is good to disable SSH access to users which don't need it is of course better security. Disabling access to ssh shell for users which don't need it prevents you for user to run malicious code usually exploits or some DDoS Fork bombs – like the infamous Linux shell Denial of Service string;

:(){ :|:&};:

Better not try above string on productive server ;)
So back to the topic here how to add Linux FTP only user;

1. Create a regular user with adduser or useradd (depending) on GNU / Linux distribution

adduser is available across most Linux distributions nowadays, however I remember in past there was some distros which had useradd instead. Anyways for most adduser should be ok. As of time of writting both 3 main stream Linux distributions Slackware, Debian and Fedora has adduser.

linux:~#  adduser new-user-for-ftp-only

Adding user `new-user-for-ftp-only' …
Adding new group `new-user-for-ftp-only' (1006) …
Adding new user `new-user-for-ftp-only' (1005) with group `new-user-for-ftp-only' …
Creating home directory `/home/new-user-for-ftp-only' …
Copying files from `/etc/skel' …
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Changing the user information for new-user-for-ftp-only
Enter the new value, or press ENTER for the default
    Full Name []: New Linux User Only for FTP access  
    Room Number []:
    Work Phone []:
    Home Phone []:
    Other []:
Is the information correct? [Y/n] Y

linux:~#

2. Change user shell /bin/bash to /bin/false

Again depending on Linux distribution by default /bin/bash /bin/sh or /bin/whatever shell will get added. To make just created user access to SSH disabled. Change shell to /bin/false – a tiny program which just returns a FALSE value and quits immediately.

There are two ways to do so;

a) Edit directly /etc/passwd with vim / joe

linux:~# vim /etc/passwd

Go to end of file and find the record for user, should be smth like:

 

new-user-for-ftp-only:x:1005:1006:New Linux User Only for FTP access,,,:/home/new-user-for-ftp-only:/bin/bash

Change to;

new-user-for-ftp-only:x:1005:1006:New Linux User Only for FTP access,,,:/home/new-user-for-ftp-only:/bin/false

b) Use chsh cmd

linux:~# chsh new-user-for-ftp-only

Changing the login shell for new-user-for-ftp-only
Enter the new value, or press ENTER for the default
    Login Shell [/bin/bash]: /bin/false

linux:~# grep -i new-user-for-ftp-only /etc/passwd

new-user-for-ftp-only:x:1005:1006:New Linux User Only for FTP access,,,:/home/new-user-for-ftp-only:/bin/false

3. Testing if ssh access to new user is disabled

linux:~# ssh new-user-for-ftp-only@localhost

new-user-for-ftp-only@localhost's password:
Linux noah 2.6.32-5-amd64 #1 SMP Mon Feb 25 00:26:11 UTC 2013 x86_64

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Connection to localhost closed.

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Linux Currency convert GUI tool KeuroCalc / Convert world currencies Desktop Linux application, Convert USD to EUR

Thursday, April 25th, 2013

keurocalc Linux convert us dollars to euro and to rest of major world currencies

If you happen to run a small business or you're just an adventurer who use Linux for his notebook Desktop. Sooner or later you will end up needing Linux software to convert between world currencies. Some might argue that such a software is obsolete since already there are the Google Currency Converter and plenty of other (online) web currency converter sites. However for people like to use desktop applications like me it is much better to use a separate desktop tool which do currency convertion. If this is the case with and you happen to use Debian GNU / Linux, Ubuntu Fedora or any other main stream Linux distribution on your Linux powered Laptop or Tablet you will be surely happy to know about KEuroCalc – Universal Currency Converter. As all "K"-named starting Linux apps unfortunately keurocalc is using QT KDE graphic library and thus whenever used on GNOME it starts a bunch of KDE services (kedinit,klauncher, kded), however the load of this few on any modern notebook or PC is neglectably low so for most users the only disadvantage of kerocalc might be interface is looking a bit different compared to rest of Gnome GTK+ programs.

To install keurocalc on deb based Linuces e.g. – Debian / Ubuntu, ArchLinux ..:

noah:~# apt-cache show keurocalc|grep -i description -A 3

Description: universal currency converter and calculator – binary package
 KEurocalc is a universal currency converter and calculator.
 It downloads latest exchange rates directly from the
 European Central Bank and the Federal Reserve Bank of New York.
 

noah:~# apt-get install --yes keurocalc

Reading package lists… Done
Building dependency tree      
Reading state information… Done
The following NEW packages will be installed:
  keurocalc
0 upgraded, 1 newly installed, 0 to remove and 23 not upgraded.
Need to get 0 B/87.8 kB of archives.
After this operation, 319 kB of additional disk space will be used.
Selecting previously deselected package keurocalc.
(Reading database … 393466 files and directories currently installed.)
Unpacking keurocalc (from …/keurocalc_1.0.3-2_amd64.deb) …
Processing triggers for hicolor-icon-theme …
Processing triggers for man-db …
Processing triggers for menu …
Processing triggers for gnome-menus …
Processing triggers for desktop-file-utils …
Setting up keurocalc (1.0.3-2) …
Processing triggers for menu …

On Fedora, CentOS and rest of RPM based Linux distros keurocalc is installable too out of default package repositories:

[root@fedora ~]# yum -y -q install keurocalc
....

 

Here is a snapshot of keurocalc GUI interface;

Linux Universal Currency Converter Keurocalc

Keurocalc Linux universal currency converter settings screenshot

As you see from settings screenshot, information about rates can be obtained from 2 sources; – European Central Bank and New York Federal Reserve Bank. I give a try also to Euro, no network access (fixed rates only) method but unfortunately by choosing it you can only convert between Fixed Currencies (currencies which are already not in use – in EU member states who dropped their local currencies in favor of EURO).

I've tested the program and it works good, the disadvantage is convertion between some of the World currencies of countries with non-transparent planned (Soviet like) economies for example Belarus is not among app list of convertable currencies.

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How to check what process is listening on network port with: lsof & fuser commands in Linux / BSD

Saturday, March 16th, 2013

It is a common thing for me as a Linux and FreeBSD sysadmin to know what process assignes to which port number? I'm sure many novice system administrators will end up sooner or later with same question. Knowing what kind of processes has listening to TCP and UDP protocol / ports is a must to have a proper configured Linux / BSD system. In Linux there are two commands ( lsof and fuser) with which you can get various extra PID information on running processes (i.e. get information which cannot otherwise be obtained via the usual ps and netstat  To use them on most Linux distributions, you will have to have them installed.

1. Install fuser / lsof on Linux / BSD

a) On RPM based Linux distros – Fedora, CentOS, RHEL, SuSE /sbin/fuser is usually part of base install psmisc rpm package, however /usr/sbin/lsof is not among standard installed rpms, so you have to manually install via yum:

[root@centos ~]# yum install -y lsof
….

b) On Deb based Linuxes (Debian, Ubuntu, Mint, ArchLinux etc.). both lsof and fuser has to be installed via a separate packages non-part of Debian base install packs.

server:~# apt-get --yes install lsof fuser
....

On Debian full path location of both is in /bin/fuser and /usr/bin/lsof.

Two tools are precious swiss army knife outfit to use, whether you doubt someone cracked into a server or in doubt you might have "hidden" cracker processes on server.

c) Install fuser on Free/Net/Open/ BSD

bsd# cd /usr/ports/sysutils/fuser
bsd# make install clean
....
bsd# cd /usr/ports/sysutils/lsof
bsd# make install clean
....

2. Using fuser and lsof to look up process PIDs assigned to port numbers

lsof name is derived from List Open Files, as we know in UNIX, GNU / Linux,  *BSD everything on the system is a file, thus to get all kind of information concerning all active files (i.e. ports, PIDs, procotols and process names;

server:~# lsof +M -i4 | less

COMMAND     PID     USER   FD   TYPE   DEVICE SIZE/OFF NODE NAME
portmap    1317   daemon    4u  IPv4     3930      0t0  UDP *:sunrpc[portmapper]
portmap    1317   daemon    5u  IPv4     3939      0t0  TCP *:sunrpc[portmapper] (LISTEN)
rpc.statd  1329    statd    4u  IPv4     3974      0t0  UDP *:657
rpc.statd  1329    statd    6u  IPv4     3983      0t0  UDP *:28530[status]
rpc.statd  1329    statd    7u  IPv4     3986      0t0  TCP *:58515[status] (LISTEN)
apache2    1625 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    1625 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
sshd       1918     root    3u  IPv4     4945      0t0  TCP *:ssh (LISTEN)
miniserv.  2155     root    5u  IPv4     5299      0t0  TCP *:20000 (LISTEN)
miniserv.  2155     root    6u  IPv4     5300      0t0  UDP *:20000
miniserv.  2161     root    6u  IPv4     5367      0t0  TCP *:webmin (LISTEN)
miniserv.  2161     root    7u  IPv4     5368      0t0  UDP *:10000
ntpd       2172      ntp   16u  IPv4     5395      0t0  UDP *:ntp
ntpd       2172      ntp   18u  IPv4     5402      0t0  UDP localhost:ntp
ntpd       2172      ntp   19u  IPv4     5403      0t0  UDP iqtest.soccerfame.com:ntp
ntpd       2172      ntp   20u  IPv4    16028      0t0  UDP secure.broomlake.com:ntp
apache2    4505 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    4505 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    4539 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    4539 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    4780 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    4780 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    4900 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    4900 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    4907 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    4907 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    4915 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    4915 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5067 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5067 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5133 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5133 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5134 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5134 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5148 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5148 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5152 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5152 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5259 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5259 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5265 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5265 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5266 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5266 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5346 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5346 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5356 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5356 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5467 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5467 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5523 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5523 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5568 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5568 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5715 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5715 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5716 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5716 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5758 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5758 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    5789 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    5789 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2    6106 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2    6106 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   16608 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   16608 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   16904 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   16904 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   17124 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   17124 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   17280 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   17280 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   20855 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   20855 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   20920 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   20920 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   21023 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   21023 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   22182 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   22182 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   23307 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   23307 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   23366 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   23366 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   23408 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   23408 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   23419 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   23419 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   23428 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   23428 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   23452 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   23452 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   23561 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   23561 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   23579 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   23579 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   23851 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   23851 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   24103 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   24103 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   24659 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   24659 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
sshd      25073     root    3u  IPv4 29855891      0t0  TCP iqtest.soccerfame.com:ssh->pc-freak.net:50176 (ESTABLISHED)
sshd      25084     hipo    3u  IPv4 29855891      0t0  TCP iqtest.soccerfame.com:ssh->pc-freak.net:50176 (ESTABLISHED)
apache2   25089 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   25089 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   26737 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   26737 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   27243 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   27243 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   27282 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   27282 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   27633 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   27633 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   28205 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   28205 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   29244 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   29244 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   29372 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   29372 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   29411 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   29411 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   29462 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   29462 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   29548 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   29548 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   30161 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   30161 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   31876 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   31876 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   31958 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   31958 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   32052 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   32052 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   32061 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   32061 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   32143 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   32143 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   32149 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   32149 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   32440 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   32440 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   32635 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   32635 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   32790 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   32790 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   40211 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   40211 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   40309 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   40309 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   40432 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   40432 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   40476 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   40476 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   46319     root    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   46319     root    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   46438 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   46438 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   46439 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   46439 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   46440 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   46440 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   46441 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   46441 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   46442 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   46442 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   46443 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   46443 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   46509     root    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   46509     root    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   46510     root    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   46510     root    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   46515     root    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   46515     root    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   51287 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   51287 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   51485 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   51485 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   51804 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   51804 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
named     54418     bind   20u  IPv4 31298857      0t0  TCP localhost:domain (LISTEN)
named     54418     bind   21u  IPv4 31298859      0t0  TCP iqtest.soccerfame.com:domain (LISTEN)
named     54418     bind   22u  IPv4 31298861      0t0  TCP secure.broomlake.com:domain (LISTEN)
named     54418     bind   23u  IPv4 31298865      0t0  TCP localhost:953 (LISTEN)
named     54418     bind  512u  IPv4 31298856      0t0  UDP localhost:domain
named     54418     bind  513u  IPv4 31298858      0t0  UDP iqtest.soccerfame.com:domain
named     54418     bind  514u  IPv4 31298860      0t0  UDP secure.broomlake.com:domain
named     54418     bind  515u  IPv4 31298864      0t0  UDP *:domain
proftpd   62010  proftpd    1u  IPv4 31306260      0t0  TCP *:ftp (LISTEN)
mysqld    62420    mysql   11u  IPv4 31306903      0t0  TCP *:mysql (LISTEN)
apache2   62582 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   62582 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   62845 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   62845 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)
apache2   64748 www-data    3u  IPv4     5456      0t0  TCP *:www (LISTEN)
apache2   64748 www-data    4u  IPv4     5458      0t0  TCP *:https (LISTEN)

Above lsof command lists all active listening processes port number on UDP and TCP/IP 4 proto with the assigned process PID number (in second column). This is very useful if you find out to have listening service on port number and you cannot figure out what process name exactly is listening.

A classic example, where this is very helpful is if you have a listening process on SMTP port 25 and you cannot identify what kind of mail server is taking up the port? This has happened me many times on Debian Linux based hosts, which by default had priorly installed sendmail and I later removed sendmail to install Postfix or Exim SMTP.
To find out what is assigning port 25, you had to grep the protocol name from all binded host processes, like so:

 

server:~# lsof +M -i4 | grep -i smtp

exim4     17550     root    3u  IPv4 31577966      0t0  TCP localhost:smtp (LISTEN)

Whether you want to get information on Process ID, binding other random port lets say port 10000, following same logic you can grep it:

server:~# lsof +M -i4 |grep -i 10000
miniserv.  2161     root    7u  IPv4     5368      0t0  UDP *:10000

To get rid of a process for which you're unsure what kind of (/etc/init.d/service-name) init script is starting it, you can then use kill cmd to stop it;

server:~# kill -9 2161

Second approach to find out what kind of process is listening on a random port or socket, lets say port num 58515 is by using fuser.

 

 

server:~# netstat -ltn4
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State     
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN    
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN    
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN    
tcp        0      0 0.0.0.0:10000           0.0.0.0:*               LISTEN    
tcp        0      0 0.0.0.0:58515           0.0.0.0:*               LISTEN    
tcp        0      0 0.0.0.0:21              0.0.0.0:*               LISTEN    
tcp        0      0 77.92.85.71:53          0.0.0.0:*               LISTEN    
tcp        0      0 109.123.106.44:53       0.0.0.0:*               LISTEN    
tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN    
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN    
tcp        0      0 127.0.0.1:953           0.0.0.0:*               LISTEN    
tcp        0      0 0.0.0.0:443             0.0.0.0:*               LISTEN    
tcp        0      0 0.0.0.0:20000           0.0.0.0:*               LISTEN    

Below netstat cmmand, lists all active listening processes on respective IP address and port for protocol TCPIP v.4.

Hence on to get more information on what process is listening on port 58515?

server:~#  fuser -v 58515/tcp

                     USER        PID ACCESS COMMAND
58515/tcp:           statd      1329 F…. rpc.statd

Once you know what is listening, whether you want to kill it this is also possible directly through fuser;

 

server:~# fuser -vk 58515/tcp

As a close-up, I will say fuser and lsof are two must have software tools on any productive server. It is among the critical applications admin has to install during initial server set-up. fuser and lsof helps me often in my sysadmin work, it was more than once I've used them to identify script-kiddies exploit scanners running as a standard process names, as well secretly listening on weird port number  cracker back-doors.

Hopefully this little article, helps someone learn something new. Plenty is written and will be written and if one takes the time to research he can learn much, much more. I'm sure my tiny article is nothing new under the sun for old-school admins, I still hope it will be of use to novice. I'm looking forward to hear if I'm missing some neat use or some interesting case, when lsof or fuser "saved your ass" :)
 

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Secure delete files irreverseble on Debian and Fedora GNU / Linux

Thursday, February 21st, 2013

I just read an article in Linux-Magazine on Advanced File Management named – "Beyond the Basics". Most of what the article says is pretty trivial and known by any Linux enthusiast average user and administrator. There was one command mentioned shred which is probably not so well known among Free Software users shred allows the user to "secure delete files" / from the hard disk irreversible.

The tool is part of coreutils package and available across mostly all Linux distributions including Debian / Ubuntu debian derivatives and the RedHat based distros CentOS, Fedora, RHEL etc.

Just for info for those who don't know how to check, to which package a command belongs with rpm and dpkg, here is how;

[hipo@centos ~]$ rpm -qf /usr/bin/shred
coreutils-5.97-23.el5_4.2

hipo@debian:~$ dpkg -S /usr/bin/shred
coreutils: /usr/bin/shred

Here is how to delete a sample file ovewritting 3 times (-n2 – means 3 because in comuters we know we countr from 0 – 0 1 2 3), the z option fills up with zeros after overwritting the file ( just like seen on paste), -v option shows verbose what shred is doing and -u option truncates removes file after overwritting

noah:/var/tmp# shred -n2 -zvu crash20121113021508.txt
shred: crash20121113021508.txt: pass 1/3 (random)…
shred: crash20121113021508.txt: pass 2/3 (random)…
shred: crash20121113021508.txt: pass 3/3 (000000)…
shred: crash20121113021508.txt: removing
shred: crash20121113021508.txt: renamed to 00000000000000000000000
shred: 00000000000000000000000: renamed to 0000000000000000000000
shred: 0000000000000000000000: renamed to 000000000000000000000
shred: 000000000000000000000: renamed to 00000000000000000000
shred: 00000000000000000000: renamed to 0000000000000000000
shred: 0000000000000000000: renamed to 000000000000000000
shred: 000000000000000000: renamed to 00000000000000000
shred: 00000000000000000: renamed to 0000000000000000
shred: 0000000000000000: renamed to 000000000000000
shred: 000000000000000: renamed to 00000000000000
shred: 00000000000000: renamed to 0000000000000
shred: 0000000000000: renamed to 000000000000
shred: 000000000000: renamed to 00000000000
shred: 00000000000: renamed to 0000000000
shred: 0000000000: renamed to 000000000
shred: 000000000: renamed to 00000000
shred: 00000000: renamed to 0000000
shred: 0000000: renamed to 000000
shred: 000000: renamed to 00000
shred: 00000: renamed to 0000
shred: 0000: renamed to 000
shred: 000: renamed to 00
shred: 00: renamed to 0
shred: crash20121113021508.txt: removed
 

One common use of shred is by sysadmins who has to prepare old server containing lets say client data (SQL) – mail boxes or just file data and then sell it to third parties making sure data will be un-restorable for the new owner. Also shred is used a lot by crackers who set up "time bombs" activated on user activity or inactivity to destroy evidences in case of crackers PC is being captured by police. Though shred cannot guarantee 100% that deleted data can't be recoved within a special data recovery lab in most of cases it is enough to assure data with it will be almost impossible to recover.

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How to keep track of All User accounts executed commands, highest CPU consumers and user times on Linux

Tuesday, February 5th, 2013

Linux accounting keeping an eye on all user run commands time accounting find cpu eaters

For people interested into statistics of how Linux existing users are spending, there log in times and what kind of commands each of users is executing, take a look at acct
acct is existing on all mainstream Linux distributions is a great sysadmin tool. acct is a great tool whether you have a system where a multitude of users you don't trust has to be monitored. It is an absolutely must have for anyone willing to run, lets say  experimental honeypot or  free shell host. acct is useful for paranoid sysadmins who like to always knows what there users are running as well as in situation where some of users is suspected to be a potential cracker trying to root the host.

Below is description of acct package on Debian:

# apt-cache show acct| grep -i description -A 8
Description: The GNU Accounting utilities for process and login accounting
 GNU Accounting Utilities is a set of utilities which reports and summarizes
 data about user connect times and process execution statistics.
 .
 "Login accounting" provides summaries of system resource usage based on connect
 time, and "process accounting" provides summaries based on the commands
 executed on the system.
 .
 The 'last' command is provided by the sysvinit package and not included here.

To start using acct, just install it with usual:

# apt-get install --yes acct

(Whether on Debian / Ubuntu Linux);

On Fedora, CentOS and RHEL and other RPM based Linuxes issue;

yum --y install psacct

On deb based Linux distributions, whether acct collects statistics is controlled via:

/etc/default/acct

# cat /etc/default/acct
# Defaults for acct

# If you want to keep acct installed, but not started automatically, set this
# variable to 0. Because /etc/cron.daily/acct calls the initscript daily, it is
# not sufficient to stop acct once after booting if your machine remains up.
ACCT_ENABLE="1"

# Amount of days that the logs are kept.
ACCT_LOGGING="30"

After installed to start collecting user "process accounting" data run acct via init script;

# /etc/init.d/acct start
Turning on process accounting, file set to '/var/log/account/pacct'.
Done..

The file gathering info on system usage, CPU load, user ran commands /var/log/account/psacct is a binary and unreadable tailing it with tail -f .

On CentOS / Fedora Linux to Enable acct account statistics gathering in future boot and from present moment on do;

# chkconfig psacct on
# /etc/init.d/psacct start

1. Find out all commands executed by Linux user account (lastcomm)

Once user accounting is running to get information of every command ever executed on user shell use lastcomm cmd. For example:

# lastcomm hipo

bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.03 secs Tue Feb  5 00:20
sed                    hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
uname                  hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
dircolors              hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
uname                  hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
ls                     hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.03 secs Tue Feb  5 00:20
sed                    hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
uname                  hipo     pts/1      0.00 secs Tue Feb  5 00:20
bash              F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
id                     hipo     pts/1      0.00 secs Tue Feb  5 00:20
mesg                   hipo     pts/1      0.00 secs Tue Feb  5 00:20
verse                  hipo     pts/1      0.00 secs Tue Feb  5 00:20
cowrand                hipo     pts/1      0.00 secs Tue Feb  5 00:20
cowsay                 hipo     pts/1      0.03 secs Tue Feb  5 00:20
cowrand           F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
head                   hipo     pts/1      0.00 secs Tue Feb  5 00:20
tail                   hipo     pts/1      0.00 secs Tue Feb  5 00:20
head                   hipo     pts/1      0.00 secs Tue Feb  5 00:20
ls                     hipo     pts/1      0.00 secs Tue Feb  5 00:20
cowrand           F    hipo     pts/1      0.00 secs Tue Feb  5 00:20
awk                    hipo     pts/1      0.00 secs Tue Feb  5 00:20
wc                     hipo     pts/1      0.00 secs Tue Feb  5 00:20
ls                     hipo     pts/1      0.00 secs Tue Feb  5 00:20

A lot of the initial commands shown to run on pts/1 is not actual commands, by the user but are just stuff run on user login time via /etc/bash.bashrc, /etc/profile, ~/.bashrc. ~/.bash_profile.

lastcomm displayed output from 2nd column is a special flag giving more information on how and for what purpose command was executed. In above output
F
– indicates the command run after a fork.
X – is returned if a command exit with SIGTERM (kill signal)
D – in case of generated command core dump (D is good one to look for whether checking a suspicious user profile, as it is so common exploits use core dumping to get root superuser access)
S – means the command is run with superuser privileges (this one you will see usually whether inspecting user profile of a cracker who run exploit using core dump – a lot of Ds followed by some shell code to run as superuser)

2. Get statistics on CPU use time of services (daemons) and user accounts

psacct is very handy, whether you have CPU server overloads and you have difficulty finding out what are the "CPU hungry processes". To get those use summarized accounting information tool;

# sa -m
                                     2619      31.06re       0.54cp         0avio      2907k
root                                 2448      30.19re       0.52cp         0avio      2817k
www-data                               33       0.06re       0.02cp         0avio      3687k
hipo                                   72       0.15re       0.01cp         0avio      6217k
qscand                                 11       0.36re       0.00cp         0avio      5326k
vpopmail                               48       0.25re       0.00cp         0avio      1486k
qmails                                  6       0.00re       0.00cp         0avio       968k
sshd                                    1       0.04re       0.00cp         0avio     12632k

-m (prints user summary).

3. Find all system users running certain commands

Another good use of lastcomm command is to grep over all users executed command for precise commands of interest. One very good use case is if you catch a system abuser running certain exploit or DoS tool on the host and you want to make sure no-one else on the system doesn't try running it.

# lastcomm ls
ls                     www-data __         0.00 secs Tue Feb  5 00:40
ls                     www-data __         0.00 secs Tue Feb  5 00:30
ls                     hipo     pts/7      0.00 secs Tue Feb  5 00:20
ls                     hipo     pts/1      0.00 secs Tue Feb  5 00:20
ls                     hipo     pts/1      0.00 secs Tue Feb  5 00:20
ls                     hipo     pts/1      0.00 secs Tue Feb  5 00:20
ls                     hipo     pts/1      0.00 secs Tue Feb  5 00:20
ls                     hipo     pts/1      0.00 secs Tue Feb  5 00:20
ls                     www-data __         0.00 secs Tue Feb  5 00:20
ls                     root     pts/0      0.00 secs Tue Feb  5 00:10
ls                     root     pts/0      0.00 secs Tue Feb  5 00:10
ls                     www-data __         0.00 secs Tue Feb  5 00:10
 

4. Get statistics of most active system users in hours

There is one tool called ac, which is similar in what it does to last command, just like last it uses /var/log/wtmp binary log file to get its user login times stats . The difference is ac provides more and better structured user login time length info.

Its very useful if you want to have idea, which user spends most time connected to host.

$ ac -p
    sic                                  4.86
    hipo                                 4.80
    root                                25.80
    play                                 0.02

To get general info on how much overall hours all existing users spend doing stuff on node;

$ ac total 35.61

To know which days from the month users were most active:

$ ac -d
Feb 1 total 14.54
Feb 2 total 0.97
Feb 3 total 12.47
Feb 4 total 5.96
Today total 1.73

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Adding Teamviewer to auto start on Linux GNOME login

Friday, February 1st, 2013

Administrating Linux via graphical interface is not common, however sometimes it is necessery. There are plenty of ways to remotely administrate with GUI Linux. You can connect to remote Xserver and launch X session via xinit, connect via (Gnome Display Manager) GDM, use nomachine NX server / client (if you're on slow connection line) or use the good old Teamviewer.

As Teamviewer works pretty well on both Windows and Linux in last times I like using teamviewer as a standard. It is freeware and it often disconnects with the annoying Trial message, but in general for managing something quick on remote desktop it is nice.

To use teamviewer, you need to have it installed on the Linux host via deb or rpm:

Whether on Debian / Ubuntu use:

 

# wget http://www.teamviewer.com/download/version_8x/teamviewer_linux_x64.deb
.....
# dpkg -i teamviewer_linux_x64.deb
...
....

 

On Fedora, CentOS, RHEL run:

# wget -q http://www.teamviewer.com/download/teamviewer_linux.rpm
# rpm -Uvh teamviewer_linux.rpm
.....

Once package is installed teamviewer is installed in /opt/teamviewer/* there is a tiny wrapper run script in /usr/bin/teamviewer – evoking TeamViewer to be run via wine emulation.

Hence to make TeamViewer start on certain user GNOME login the script has to run on GNOME user login session.
In both GNOME 2 and GNOME 3 what is run on user login is managed through gnome-session-properties thus /usr/bin/teamviewer has to be set to run through gnome-session-properties (to run it press ALT+F2 or type it directly in gnome-terminal)

user@linux:~$ gnome-session-properties

A window like in below screenshot pops up and from there Add TeamViewer.

Adding Teamviewer to auto start on Linux Debian Fedora CentOS GNOME non privileged user

To be able to later connect via a Remote host with another TeamViewer peer launch TeamViewer and configure permanent password through menus:

Extras -> Options -> Security

teamviewer extras options security configuring teamviewier permanent password for ID

All left is to write down your Teamviewer Remote Connect ID and permanent set password

Teamviewer remote connect ID screnshot Linux

After next succesful GNOME login teamviewer will just pop-up. Enjoy

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How to record microphone input sound (only) using good old ffmpeg

Tuesday, December 25th, 2012

The good old ffmpeg, along with being able to capture sound and video from your Linux Desktop or a certain Window and Skype whatever WebCamera input is also able to record sound from both camera or embedded laptop microphone. Here is how:

# ffmpeg -f alsa -ac 2 -i pulse   -acodec pcm_s16le -vcodec libx264 -vpre lossless_ultrafast -threads 0  -y  myVOICE.wav

This as you can see from arguments, uses GNOME's pulseaudio (audio service) and ALSA. Sound is first streamed through alsa and then the sound inflow is passed to be processed and multipled in a separate sound channel by pulseaudio. This method though said to be working fine on Ubuntu Linux is not working well on some other Linux distributions like Debian if one is using ALSA configured to use a software sound multiplexor via the so called – alsa dsnoop interface (previously I write how to use it in order to make Skype and other programs use SoundBlaster proper – article is here)

Below is the output warning I got whether trying ffmpeg with -f alsa and -i pulse arguments:

hipo@noah:~/Desktop$ ffmpeg -f alsa -ac 2 -i pulse   -acodec pcm_s16le -vcodec libx264 -vpre lossless_ultrafast -threads 0  -y  myVOICE.wav
FFmpeg version SVN-r25838, Copyright (c) 2000-2010 the FFmpeg developers
  built on Sep 20 2011 17:00:01 with gcc 4.4.5
  configuration: --enable-libdc1394 --prefix=/usr --extra-cflags='-Wall -g ' --cc='ccache cc' --enable-shared --enable-libmp3lame --enable-gpl --enable-libvorbis --enable-pthreads --enable-libfaac --enable-libxvid --enable-postproc --enable-x11grab --enable-libgsm --enable-libtheora --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libx264 --enable-libspeex --enable-nonfree --disable-stripping --enable-avfilter --enable-libdirac --disable-decoder=libdirac --enable-libschroedinger --disable-encoder=libschroedinger --enable-version3 --enable-libopenjpeg --enable-libvpx --enable-librtmp --extra-libs=-lgcrypt --disable-altivec --disable-armv5te --disable-armv6 --disable-vis
  libavutil     50.33. 0 / 50.43. 0
  libavcore      0.14. 0 /  0.14. 0
  libavcodec    52.97. 2 / 52.97. 2
  libavformat   52.87. 1 / 52.87. 1
  libavdevice   52. 2. 2 / 52. 2. 2
  libavfilter    1.65. 0 /  1.65. 0
  libswscale     0.12. 0 /  0.14. 1
  libpostproc   51. 2. 0 / 51. 2. 0
[alsa @ 0x633160] capture with some ALSA plugins, especially dsnoop, may hang.

where concrete programs, are run which take use of OSS (Open Sound System) – an already obsolete sound architecture. By the way on current Debian / Fedora etc. Linux-es OSS is managed and played only, whether few kernel modules are already  pre-loaded, below are the ones as pasted from my Debian Squeeze:

# lsmod | grep -i oss
snd_pcm_oss            32591  0
snd_mixer_oss          12606  1 snd_pcm_oss
snd_pcm                60487  3 snd_hda_intel,snd_hda_codec,snd_pcm_oss
snd                    46526  15 snd_hda_codec_analog,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_rawmidi,snd_seq,snd_timer,snd_seq_device

The oss processed sound recording from ffmpeg is not working, well on my Linux, cause I have my custom (non-Debian) native binary Firefox downloaded and installed from Firefox's website.The browser is compiled to open automatically /dev/dsp which in practice uses the above-mentioned OSS listed modules, which on their behalf when used break out the sound processed by alsa and respectively pulseaudio (those who use Linux for longer time should remember in the times of OSS only one certain sound stream was possible to be processed / played on Linux historically before ALSA come to scene to be "defacto" standard kernel sound processor. Well ofcourse firefox developers who compiled the Firefox for Linux probably was using Slackware or some other Linux distro which probably used to play sound still via OSS or maybe they compiled it so thinking OSS because of its historical importance is still supported by more Linux distributions than alsa is. I like the custom compiled Firefox to run on my Debian instead of default Debian Squeeze (IceWeasel) cause firefox.org ,Firefox version is much newer and supports better latest HTML5  as well as it includes ability to download and apply automatic updates to the latest version provided by Firefox team. However I fou

Thus for Linux users like me using latest firefox binary from firefox.org (in parallel) with opened Firefox browser to record sound from Webcam or Embedded notebook mic the obsolete OSS has to be used, here is how:

# ffmpeg -f oss -ac 2 -i /dev/dsp   -acodec pcm_s16le -vcodec libx264 -vpre lossless_ultrafast -threads 0  -y  my-recorder-VOICE.wav

Enjoy ;)

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After a loooongg, looong waiting finally a New Version of Skype 4.0 is out – Skype 4 on Debian GNU / Linux short review

Sunday, June 17th, 2012

After about 3 years of no new version for GNU / Linux finally Skype has released a new version of Skype.
I thought already there will be never a new skype version out for GNU / Linux, since the moment Microsoft purchased skype.

Now suddenly and quite in quiet the new version of Skype 4.0 is out for download from Skype's website. The latest Skype download for Linux is to be found here

As of time of writting this post there are Skype 4 versions for following Linux-es;;;
 

  • Ubuntu 10.04 32 / 64-bit (probably would work fine on latest Ubuntus too)
  • Debian 6.0 Squeeze 32 / 64-bit
  • Fedora 16 / 32 bit
  • OpenSUSE 12.1 32bit (only)
  • Most likely the Ubuntu release of skype 4 will work flawlessly on Linux Mint and other debian derivatives.The The release mentions, Skype 4 is supposed to have 4 major advancements and the gap in interface and usability with latest Mac OS and M$ Windows Skype versions is now filled.The four major changes said in the announcement are;;;

  • 1. a new Conversations View where users can easily track all of their chats in a unified window.
    Those users who prefer the old view can disable this in the Chat options;
  • 2. a brand new Call View;
  • 3.Call quality has never been better thanks to several investments we made in improving audio quality;
  • 4. Improved video call quality and extended support for more cameras.
  • Some of the minor improvements in those

  • new Linux skype
  • are:- improved chat synchronization- new presence and emoticon icons- the ability to store and view phone numbers in a Skype contact's profile- much lower chance Skype for Linux will crash or freeze- chat history loading is now much faster- support for two new languages: Czech (flag:cz) and Norwegian (flag:no)Just like with prior Skype releases 2.0 and 2.2beta this release comes with almost same list of non-english language support ,,,Seeing those announcement, I've hurried to download and test skype 4 on my 64-bit desktop running Debian 6 Squeeze.Once downloaded to install the pack skype-debian_4.0.0.7-1_amd64.deb I used the usual dpkg -i i,e,;;;noah:~# dpkg -iskype-debian_4.0.0.7-1_amd64.deb…………..Just like the release announcement mentions the first initial launch of Skype 4 took about 3 or 4 minutes doing something (probably sending half of my hard disk data to Microsoft :) :) :) ) along with importing the prior skype data and chat history :) The minimum software dependencies for correct operation of Skype are:Qt libraries; D-Bus; libasound and pulseaudioHere are few screenshots of Skype 4 to give you an idea what to expect:The Skype Options is almost identical to Skype 2.2. One interesting new feature I've noticed is Skype WIFIUnfortunately to use Skype WIFI you need to have purchased skype credits.Another notable difference is the organization of Skype Chats, which is more like in the good old times of mIRC and IRC chat clientsHere is also the list of Skype emoticons including bundled with Skype 4:The "look & feel" of the new interface gives the impression of seriously improved Skype client stability too.There was a minor trouble with the voice recording (microphone) with Skype 4;To make the microphone work properly I had to raise up the mic volume from PulseAudio settings in Skype options.Well that's all the only unpleasent thing for this new skype is it is using KDE's libQT and seems not to have a native interface for GNOME via GTK2. If we put away this I guess this version of Skype is much more stable and therefore I would recommend anyone to update.Of course we never know if this new updated more stable Skype release is not filled up with backdoors or does not transfer all our conversations to microsoft but we didn't know that even when Skype was not Microsoft's so and since it is not a free software I guess it doesn't matter so much.As you can guess Microsoft has imposed centralization on Skype protocol so connecting the peers is now done by Microsoft servers this news is another intriguing one.According to one recent article from May 1, 2012 Microsoft Skype replaces the Peer-to-Peer P2P supernodes with Linux boxes hosted by Microsoft – In short that probably means that by changing this nowdays microsoft probably now logs all chat sessions between Skype users, even it is likely the calls between users are recorded too. We all know Microsoft imperialism pretty well so I guess this is not a big news …..This new release of Skype if it is significantly more stable than it is prior releases would certainly have serious positive implication on the development and adoption of Linux for the Desktop. So far I'm sure one of the obstacles of many manufacturers of notebooks and comp equipment to ship with Linux was the lack of a stable and easy to implement skype release for Linux.Well that's all folks. Enjoy the New Skype Cheeres ! :)

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Browse the web graphically in text console TTYs with w3m-img and links2 on Debian, Ubuntu, Fedora and CentOS Linux

Sunday, May 6th, 2012

links2 (links console graphics) www browser logo picture

Lately, I'm starting to use my tty consoles more and more. Most of the people should be probably aware of the existence of lynx, elinks and w3m text browsers enabling the console geeks to browse or debug web pages in plain text mode.

Anyhow, for people who did not used one of the aforementioned browsers to text brose the net I warmly suggest you give them a try. A good review on 'em is in one of my  previous post – Text mode console browsing with lynx, elinks, w3m and links text browsers

For people dedicated to only use console and text mode console on their Personal Computer, simply installing and using this text browsers will not allow you to view any images tags in the html.

Nowdays one of the reasons many people would decide not to use console for web is because they want to see pictures. Hence I believe by having the opportunity to have almost fully functional text browsing in Linux cosnole /  terminal many might choose not to bother with heavy resource consuming desktop browsers like Firefox, Google Chrome, Opera etc..

Another good reason why you might want to use a console browser instead of its Desktop resource monsters, would be improved efficiency of work. It is a well evident fact keyboard access to commands is always faster than mouse and GUI!

Besides that, I'm convinced there should be many hard core geeks out there, who still can happily live without Macromedia Flash ads and Videos in Web. For this group of users having support for graphical browsing in console is also a must.
Following my previous thoughts there should be many people who doesn't have a specific requirement for GUI programs but still use (mutt, ssh, vim, mpg321, zgv etc.).

I'm sure there are plenty of this people who do most of their work in text console and use the X windows server in conjunction with mimalistic graphical environment like (DropBox, XFCE …) for the one and only reason to view  pictures embedded in web pages.

I'm one of all this guys prior mentioned, keen on console tty browsing. Therefore while checking the available console browsers few days ago, I've stumbled on a text console w3m browser capable of displaying website with images in console called w3m-img.

w3m-img is displays pictures in web over a plain console tty or in X terminals (mlterm, xterm etc.).

Here is the description returned by apt-cache show w3m-img

debian:~# apt-cache show w3m-img|grep -i description -A 3
Description: inline image extension support utilities for w3m
w3m-img provides some utilities to support inline images for w3m
on terminal emulator in X Window System environments and Linux
framebuffer.

w3m-img doesn't rely on svgalib for displaying the pictures, but comes with its own written console image display & rendering library called w3mimgdisplay. – /usr/lib/w3m/w3mimgdisplay.

One w3m-img pre-requirement in order to be able to display pictures in plain text console ttys is to have the Linux kernel framebuffer enabled..

Actually, framebuffer is enabled by default on latest stable Debian and derivatives as well as on most other Linux releases as of time of writing.
Framebuffer is also active on other RPM based distros (Fedora, CentOS, SuSE) etc.

The Frambebuffer on or off is controlled via some directives added in grub or lilo configuration files – (depending on the installed boot loader).

Some people can only boot their PCs with the framebuffer kernel support switched off at boot time or the system will not boot Linux at all.
Unfortunately this unlucky ones, would not be able to use the picture rendering w3m-img capabilities but don't be desperate, there is hope :)

For people who can't run their Linux distro with a framebuffer kernel support enabled there is a custom hacked version of linksconsole text browser called links-graphic. links-graphic supports both console graphical text browsing using the framebuffer or alternatively svgalib as a console graphics render machine.

I used to be actively using links-graphics WWW browser quite often about 8 years ago and just remembering it brings me good memories of the good old console "hacking" years :)

Anyways, w3m-img packaged version is currently available for both rpm and deb based Linux distributions. Here is how to install on both.

1.Install and use w3m-img on Debian, Ubuntu, Mint Linux-es

debian:~# apt-get --yes install w3m-img
....

This should install w3m-img, if of course there is already no previous install of w3m package on the system.

In case you have the w3m deb installed, you will have to first remove the existing w3m installed version before installing the w3m-img package, otherwise you will probably end up with an installation conflict (at least I got such a dependency conflict while apt-getting). Probably the conflict would never occur if aptitude install w3m-img is used instead of apt ….

Usage of w3m-img is exactly the same as using the w3m text only browser version. Below is a screenshot example of w3m-img in action:

debian:~# w3m http://images.google.com

w3m-img text (console) browsing images.google.com screenshot

Jesus Christ Pantocrator Orthodox icon google image search screenshot Debian Squeeze Linux

As you can see in the upper screenshots w3m-img displays pictures pretty nice, whether even images.google.com search functionality works fine.

Generally IMHO a lot of pages looks cool with w3m-img.
Some elements placement during rendering, comes at odd positions but this is normal, since original w3m text browser doesn't have any support for Javascript 1 / 2.

For those people who would like to have both javascript basic support and images in a plain text console browsing you, again you will have to compile links2 WWW browser from source manually with svgalib support enabled.

2. Installing w3m-img to text-browse with images on Fedora, CentoS, RHEL, Redhat etc.

[root@centos ~]# yum -y install w3m-img
....

A very cool thing of w3m graphical console browser is it support  most major image formats including animated GIF files :)

The way animated GIFs are viewed is very old school, here is a notice extracted from README.img contained in the pack.
 

Notice
If you want to see GIF animation, please hit a suitable key, such
as 'h', 'l', etc., repeatedly, because a frame is rewritten
according to the re-drawing demand from w3m.
Some code in w3mimg/fb/fb.c was originally written by Mr. Yamasaki.

http://www.sainet.or.jp/~yamasaki/download/fb-sample.tar.gz

As one can read in order to see an animated GIF file with w3m you will have to keep pumping the h or l key or Enter key :D :D :D (like a nintendo game ain't it?)

Here is the also the complete list of Supported browser features mentioned in README.img
 

Support

* Display inline image (GIF,PNG,JPEG, etc.) on terminals
(xterm,rxvt, etc.) of X11 or Linux framebuffer device.
* Support inline image of img tag.
Support of attributes "width", "height", and "align".
* Direct display of image file which header is "Content-type: image/*"
* Support of
tag.
Support of attributes "shape" and "coords" of
tag.
* Support of an attribute "ismap" of img tag.
"w3m" adds coordinate of the cursor as ?, to url, and sends url.
* Support of an attribute "type=image" of img tag.
"w3m" sends coordinate of the cursor as .x=&.y=.
* Asynchronous loading of image files.
* Using cache of image file as pixmap.
* Support of GIF animation when use GdkPixbuf.

Something else which I find worthy to mention is the browser behaviour, whether a webpage has Adobe Flash .swf or .flv files embedded. If such files are contained in website source code, they will be simply ignored and the w3m keeps running stable (no strange flash crashes! hooray!).

While website with flash is opened in w3m, Adobe Flash's field on the screen shows either a blank rectangle or an empty square (depending on the site embedded flash banner dimensions and form).

W3m-Img text web browser with picture viewing support adobe flash enabled youtube.com opened screenshot

Stability of w3m in opening flash website is something really nice. I say this because I still remember how terrible the situation with links with svgalib support compiled in used to be. I remember back in the day with links2 most "flash enabled" websites lead the browser to a ugly core dump.

3. Install and use links2 on Debian and derivatives Linux to browse in console graphically with javascript support

As aforementioned, there is a hacked version of links browser called links-graphics
This hacked version is available as a package within Debian, Ubuntu and presumably most if not all of the rest deb based Linux repos.

On Fedora and the other RPM family Linuces links-graphics, should be downloaded separately as rpm and installed and is inavailable through default rpm repositories.

On Debian distros links-graphics is available by installing links2.
debian:~# apt-get install --yes links2
....

Later to start links2 in graphics mode in lets say tty1 on a machine booted its kernel with framebuffer support, type:

debian:~# links2 -driver fb http://images.google.com

Actually links2 looks, way better in console than w3m but this is quite normal, as links is way more "user friendly GUI text browser".

For those, using their console ttys without framebuffer enabled you can alternatively run links2 with its svgalib graphics support like so:

debian:~# links2 -driver svgalib -mode 320x200x16 http://images.google.com

links graphics / xlinks images in X window on Debian GNU / Linux screenshot

Note that the svgalib driver is not working on my machine, as my Linux kernel framebuffer is already enabled. Probably if I want to use links2 through  svgalib I will have to reboot and boot machine with framebuffer kernel support switched off…

links2 also supports X window graphics and is a great for Graphical environment WWW browser substitute to CPU intensive Iceweasel / Firefox or Google Chrome.

Links2 can be also used as a default browser in X windows (GUI) with any graphic manager. In my view it is   perfect web browser  for scientists and people who does not need support for Adobe Flash Player or HTML5 standards.

To use links in XFCE or GNOME Desktop env, the quickest way is to prepare new Application Launcher to run command:

debian:~# links2 -g

Google Images links2 graphics in GNOME desktop env screenshot

It is useful to use a quick alias to links -g in my ~/.bashrc in order to allow easier browsing from console by typing xlinks someurladdress.com

If you want to add this xlinks shell alias  exec:

debian:~# echo 'alias xlinks='links2 -g $1' >> ~/.bashrc

4. Install links with graphics console support on Fedora, CentOS and RHEL

[root@fedora ~]# cd /usr/local/src
[root@fedora src]# wget -q http://jakub.horky.net/rpm/links/links-2.1pre15-2/links-2.1pre15-2.i386.rpm
[root@fedora src]# rpm -ivh --nodeps links-2.1pre15-2/links-2.1pre15-2.i386.rpm
Preparing... ########################################### [100%]
Installing... ########################################### [100%]

If you get some errors with missing libraries after installing and launching links2, try to resolve them by manually linking them with ln cmd or look for the library package rpm versions and install them via yum. Another way is to fetch the links2 source from Links2 official website links.twibright.com and build from source.

Since the last time in 8 years ago I used links2,  it evolved a lot. The version now did not crash as before with flash websites are viewed.  Generally Links2 now is way more  stable.
To sum it up most people, will probably want to use Links2 for console graphical browsing as the speed and support for HTML and Javascript and web site formatting is way advanced than w3m-img

I haven't compared the speed of opening pages, but since w3m-img is html and graphics render is more simple than xlinks I suppose at some occasions w3m-img will be faster in site rendering.
However still links2 performs really light fast and its web page opening time is swift and more than good.. If xlinks opening performance is compared to most (if not all) traditional desktop browsers used nowdays Links2 will definitely beat them.

A good links2 application instead of a traditional desktop browser is also for people who aim at  improving website browsing time.

I haven't thoroughfully enough, researched on other text console grahic browser alternatives programs. If I miss something and you know amy other better ones please let me know.

Wish you a Happy Browsing ;)

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How to make screenshot in /dev/tty console on GNU / Linux – Taking picture JPEG / PNG snapshot of text console in systems without graphical environment

Monday, April 30th, 2012

I'm used to making picture screenshots in GNOME desktop environment. As I've said in my prior posts, I'm starting to return to my old habits of using console ttys for regular daily jobs in order to increase my work efficiency. In that manner of thoughts sometimes I need to take a screenshot of what I'm seeing in my physical (TTY consoles) to be able to later reuse this. I did some experimenting and this is how this article got born.

In this post, I will shortly explain how a picture of a command running in console or terminal in GNU / Linux can be made

Before proceeding to the core of the article, I will say few words on ttys as I believe they might be helpful someone.
The abbreviation of tty comes after TeleTYpewritter phrase and is dating back somewhere near the 1960s. The TTY was invented to help people with impaired eyesight or hearing to use a telephone like typing interface.

In Unix / Linux / BSD ttys are the physical consoles, where one logs in (typing in his user/password). There are physical ttys and virtual vtys in today *nixes. Today ttys, are used everywhere in a modern Unixes or Unix like operating system with or without graphical environments.
Various Linux distributions have different number of physical consoles (TTYs) (terminals connected to standard output) and this depends mostly on the distro major contributors, developers or surrounding OS community philosophy.
Most modern Linux distributions have at least 5 to 7 physical ttys. Some Linux distributions like Debian for instance as of time of writting this, had 7 active by default physical consoles.
Adding 3 more ttys in Debian / Ubuntu Linux is done by adding the following lines in /etc/inittab:
 

7:23:respawn:/sbin/getty 38400 tty7
8:23:respawn:/sbin/getty 38400 tty8
9:23:respawn:/sbin/getty 38400 tty9

On some Linux distributions like Fedora version 9 and newer ones, new ttys can no longer be added via /etc/inittab,as the RedHat guys changed it for some weird reason, but I guess this is too broad issue to discuss ….

In graphical environments ttys are called methaphorically "virtual". For instance in gnome-terminal or while connecting to a remote SSH server, a common tty naming would be /dev/pts/8 etc.

tty command in Linux and BSDs can be used to learn which tty, one is operating in.

Here is output from my tty command, issued on 3rd TTY (ALT+F3) on my notebook:
 

noah:~# tty
/dev/tty3

A tty cmd output from mlterm GUI terminal is like so:
 

hipo@noah:~$ tty/dev/pts/9

Now as mentioned few basic things on ttys I will proceed further to explain how I managed to:

a) Take screenshot of a plain text tty screen into .txt file format
b) take a (picture) JPG / PNG screenshot of my Linux TTY consoles content

1. Take screenshot of plain text tty screen into a plain (ASCII) .txt file:

To take a screenshot of tty1, tty2 and tty3 text consoles in a txt plain text format, cat + a standard UNIX redirect is all necessery:
 

noah:~# cat /dev/vcs1 > /home/hipo/tty1_text_screenshot.txt
noah:~# cat /dev/vcs2 > /home/hipo/tty2_text_screenshot.txt
noah:~# cat /dev/vcs3 > /home/hipo/tty3_text_screenshot.txt

This will dump the text content of the console into the respective files, if however you try to dump an ncurses library like text interactive interfaces you will end up with a bunch of unreadable mess.
In order to read the produced text 'shots' onwards less command can be used …
 

noah:~# less /home/hipo/tty1_text_screenshot.txt
noah:~# less /home/hipo/tty2_text_screenshot.txt
noah:~# less /home/hipo/tty3_text_screenshot.txt

2. Take picture JPG / PNG snapshot of Linux TTY console content

To take a screenshot of my notebook tty consoles I had to first install a "third party program" snapscreenshot . There is no deb / rpm package available as of time of writting this post for the 4 major desktop linux distributions Ubuntu, Debian, Fedora and Slackware.
Hence to install snapscreenshot,I had to manually download the latest program tar ball source and compile e.g.:
 

noah:~# cd /usr/local/src
noah:/usr/local/src# wget -q http://bisqwit.iki.fi/src/arch/snapscreenshot-1.0.14.3.tar.bz2
noah:/usr/local/src# tar -jxvvvf snapscreenshot-1.0.14.3.tar.bz2

noah:/usr/local/src# cd snapscreenshot-1.0.14.3
noah:/usr/local/src/snapscreenshot-1.0.14# ./configure && make && make install
Configuring…
Fine. Done. make.
make: Nothing to be done for `all'.
if [ ! "/usr/local/bin" = "" ]; then mkdir –parents /usr/local/bin 2>/dev/null; mkdir /usr/local/bin 2>/dev/null; \
for s in snapscreenshot ""; do if [ ! "$s" = "" ]; then \
install -c -s -o bin -g bin -m 755 "$s" /usr/local/bin/"$s";fi;\
done; \
fi; \
if [ ! "/usr/local/man" = "" ]; then mkdir –parents /usr/local/man 2>/dev/null; mkdir /usr/local/man 2>/dev/null; \
for s in snapscreenshot.1 ""; do if [ ! "$s" = "" ]; then \
install -m 644 "$s" /usr/local/man/man"`echo "$s"|sed 's/.*\.//'`"/"$s";fi;\
done; \
fi

By default snapscreenshot command is made to take screenshot in a tga image format, this format is readable by most picture viewing programs available today, however it is not too common and not so standartized for the web as the JPEG and PNG.
Therefore to make the text console tty snapshot taken in PNG or JPEG one needs to use ImageMagick's convert tool. The convert example is also shown in snapscreenshot manual page Example section.

To take a .png image format screenshot of lets say Midnight Commander interactive console file manager running in console tty1, I used the command:
 

noah:/home/hipo# snapscreenshot -c1 -x1 > ~/console-screenshot.tga && convert ~/console-screenshot.tga console-screenshot.png

Linux text console tty mc screenshot with snapscreenshot terminal / console snapshotting program

Note that you need to have read/write permissions to the /dev/vcs* otherwise the snapscreenshot will be unable to read the tty and produce an error:
 

hipo@noah:~/Desktop$ snapscreenshot -c2 -x1 > snap.tga && convert snap.tga snap.pngGeometry will be: 1x2Reading font…/dev/console: Permission denied

To take simultaneous picture screenshot of everything contained in all text consoles, ranging from tty1 to tty5, issue:
 

noah:/home/hipo# snapscreenshot -c5 -x1 > ~/console-screenshot.tga && convert ~/console-screenshot.tga console-screenshot.png

Here is a resized 480×320 pixels version of the original screenshot the command produces:

All text Consoles tty1 to tty5 merged screenshot png image with snapscreenshot taken on Debian GNU / Linux

Storing a picture shot of the text (console) screen in JPEG (JPG) format is done analogously just the convert command output extension has to be changed to jpeg i.e.:
 

noah:/home/hipo# snapscreenshot -c5 -x1 > ~/console-screenshot.tga && convert ~/console-screenshot.tga console-screenshot.jpeg

I've also written a tiny wrapper shell script, to facilitate myself picture picture taking as I didn't like to type each time I want to take a screenshot of a tty the above long line.

Here is the wrapper script I wrote:
 

#!/bin/sh
### Config
# .tga produced file name
output_f_name='console-screenshot.tga';
# gets current date
cur_date=$(date +%d_%m_%Y|sed -e 's/^ *//');
# png output f name
png_f_name="console-screenshot-$cur_date.png";
### END Config
snapscreenshot -c$arg1 -x1 > $output_f_name && convert $output_f_name $png_f_name;
echo "Output png screenshot from tty1 console produced in";
echo "$PWD/$png_f_name";
/bin/rm -f $output_f_name;

You can also download my console-screenshot.sh snapscreenshot wrapper script here

The script is quite simplistic to use, it takes just one argument which is the number of the tty you would like to screenshot.
To use my script download it in /usr/local/bin and set it executable flag:
 

noah:~# cd /usr/local/bin
noah:/usr/local/bin# wget -q http://www.pc-freak.net/~bshscr/console-screenshot.sh
noah:/usr/local/bin# chmod +x console-screenshot.sh

Onwards to use the script to snapshot console terminal (tty1) type:
 

noan:~# console-screenshot.sh

I've made also mirror of latest version of snapscreenshot-1.0.14.3.tar.bz2 here just in case this nice little program disappears from the net in future times.

 

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