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Linux Bond network interfaces to merge multiple interfaces ISPs traffic – Combine many interfaces NIC into one on Debian / Ubuntu / CentOS / Fedora / RHEL Linux

Tuesday, December 16th, 2014

7 min read

how-to-create-bond-linux-agregated-network-interfaces-for-increased-network-thoroughput-debian-ubuntu-centos-fedora-rhel
Bonding Network Traffic
 (link aggregation) or NIC teaming is used to increase connection thoroughput and as a way to provide redundancy for a services / applications in case of some of the network connection (eth interfaces) fail. Networking Bonding is mostly used in large computer network providers (ISPs), infrastructures, university labs or big  computer network accessible infrastructures or even by enthusiatst to run home-server assuring its >= ~99% connectivity to the internet by bonding few Internet Providers links into single Bonded Network interface. One of most common use of Link Aggreegation nowadays is of course in Cloud environments.  

 Boding Network Traffic is a must know and (daily use) skill for the sys-admin of both Small Company Office network environment up to the large Professional Distributed Computing networks, as novice GNU /  Linux sys-admins would probably have never heard it and sooner or later they will have to, I've created this article as a quick and dirty guide on configuring Linux bonding across most common used Linux distributions.

It is assumed that the server where you need network boding to be configured has at least 2 or more PCI Gigabyte NICs with hardware driver for Linux supporting Jumbo Frames and some relatively fresh up2date Debian Linux >=6.0.*, Ubuntu 10+ distro, CentOS 6.4, RHEL 5.1, SuSE etc.
 

1. Bond Network ethernet interfaces on Debian / Ubutnu and Deb based distributions

To make network bonding possible on Debian and derivatives you need to install support for it through ifenslave package (command).

apt-cache show ifenslave-2.6|grep -i descript -A 8
Description: Attach and detach slave interfaces to a bonding device
 This is a tool to attach and detach slave network interfaces to a bonding
 device. A bonding device will act like a normal Ethernet network device to
 the kernel, but will send out the packets via the slave devices using a simple
 round-robin scheduler. This allows for simple load-balancing, identical to
 "channel bonding" or "trunking" techniques used in switches.
 .
 The kernel must have support for bonding devices for ifenslave to be useful.
 This package supports 2.6.x kernels and the most recent 2.4.x kernels.

 

apt-get –yes install ifenslave-2.6

 

Bonding interface works by creating a "Virtual" network interface on a Linux kernel level, it sends and receives packages via special
slave devices using simple round-robin scheduler. This makes possible a very simple network load balancing also known as "channel bonding" and "trunking"
supported by all Intelligent network switches

Below is a text diagram showing tiny Linux office network router configured to bond ISPs interfaces for increased thoroughput:

 

Internet
 |                  204.58.3.10 (eth0)
ISP Router/Firewall 10.10.10.254 (eth1)
   
                              | -----+------ Server 1 (Debian FTP file server w/ eth0 & eth1) 10.10.10.1
      +------------------+ --- |
      | Gigabit Ethernet       |------+------ Server 2 (MySQL) 10.10.10.2
      | with Jumbo Frame       |
      +------------------+     |------+------ Server 3 (Apache Webserver) 10.10.10.3
                               |
                               |------+-----  Server 4 (Squid Proxy / Qmail SMTP / DHCP) 10.10.10.4
                               |
                               |------+-----  Server 5 (Nginx CDN static content Webserver) 10.10.10.5
                               |
                               |------+-----  WINDOWS Desktop PCs / Printers & Scanners, Other network devices 

 

Next to configure just installed ifenslave Bonding  
 

vim /etc/modprobe.d/bonding.conf

alias bond0 bonding
  options bonding mode=0 arp_interval=100 arp_ip_target=10.10.10.254, 10.10.10.2, 10.10.10.3, 10.10.10.4, 10.10.10.5


Where:

  1. mode=0 : Set the bonding policies to balance-rr (round robin). This is default mode, provides load balancing and fault tolerance.
  2. arp_interval=100 : Set the ARP link monitoring frequency to 100 milliseconds. Without option you will get various warning when start bond0 via /etc/network/interfaces
  3. arp_ip_target=10.10.10.254, 10.10.10.2, … : Use the 10.10.10.254 (router ip) and 10.10.10.2-5 IP addresses to use as ARP monitoring peers when arp_interval is > 0. This is used determine the health of the link to the targets. Multiple IP addresses must be separated by a comma. At least one IP address must be given (usually I set it to router IP) for ARP monitoring to function. The maximum number of targets that can be specified is 16.

Next to make bonding work its necessery to load the bonding kernel module:

modprobe -v bonding mode=0 arp_interval=100 arp_ip_target=10.10.10.254, 10.10.10.2, 10.10.10.3, 10.10.10.4, 10.10.10.5

 

Loading the bonding module should spit some good output in /var/log/messages (check it out with tail -f /var/log/messages)

Now to make bonding active it is necessery to reload networking (this is extremely risky if you don't have some way of Console Web Java / VPN Access such as IPKVM / ILO / IDRAC), so reloading the network be absolutely sure to either do it through a cronjob which will automatically do the network restart with new settings and revert back to old configuration whether network is inaccessible or assure physical access to the server console if the server is at your disposal.

Whatever the case make sure you backup:

 cp /etc/network/interfaces /etc/network/interfaces.bak

vim /etc/network/interfaces

############ WARNING ####################
# You do not need an "iface eth0" nor an "iface eth1" stanza.
# Setup IP address / netmask / gateway as per your requirements.
#######################################
auto lo
iface lo inet loopback
 
# The primary network interface
auto bond0
iface bond0 inet static
    address 10.10.10.1
    netmask 255.255.255.0
    network 192.168.1.0
    gateway 10.10.10.254
    slaves eth0 eth1
    # jumbo frame support
    mtu 9000
    # Load balancing and fault tolerance
    bond-mode balance-rr
    bond-miimon 100
    bond-downdelay 200
    bond-updelay 200
    dns-nameservers 10.10.10.254
    dns-search nixcraft.net.in

 


As you can see from config there are some bond specific configuration variables that can be tuned, they can have positive / negative impact in some cases on network thoroughput. As you can see bonding interfaces has slaves (this are all other ethXX) interfaces. Bonded traffic will be available via one single interface, such configuration is great for webhosting providers with multiple hosted sites as usually hosting thousand websites on the same server or one single big news site requires a lot of bandwidth and of course requires a redundancy of data (guarantee it is up if possible 7/24h.

Here is what of configs stand for

 
  • mtu 9000 : Set MTU size to 9000. This is related to Jumbo Frames.
  • bond-mode balance-rr : Set bounding mode profiles to "Load balancing and fault tolerance". See below for more information.
  • bond-miimon 100 : Set the MII link monitoring frequency to 100 milliseconds. This determines how often the link state of each slave is inspected for link failures.
  • bond-downdelay 200 : Set the time, t0 200 milliseconds, to wait before disabling a slave after a link failure has been detected. This option is only valid for the bond-miimon.
  • bond-updelay 200 : Set the time, to 200 milliseconds, to wait before enabling a slave after a link recovery has been detected. This option is only valid for the bond-miimon.
  • dns-nameservers 192.168.1.254 : Use 192.168.1.254 as dns server.
  • dns-search nixcraft.net.in : Use nixcraft.net.in as default host-name lookup (optional).

To get the best network thorougput you might want to play with different bounding policies. To learn more and get the list of all bounding policies check out Linux ethernet Bounding driver howto

To make the new bounding active restart network:
 

/etc/init.d/networking stop
sleep 5;
/etc/init.d/networking start


2. Fedora / CentOS RHEL Linux network Bond 

Configuring eth0, eth1, eth2 into single bond0 NIC network virtual device is with few easy steps:

a) Create following bond0 configuration file:
 

vim /etc/sysconfig/network-scripts/ifcfg-bond0

 

DEVICE=bond0
IPADDR=10.10.10.20
NETWORK=10.10.10.0
NETMASK=255.255.255.0
GATEWAY=10.10.10.1
USERCTL=no
BOOTPROTO=none
ONBOOT=yes


b) Modify ifcfg-eth0 and ifcfg-eth0 files /etc/sysconfig/network-scripts/

– Edit ifcfg-eth0

vim /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none

– Edit ifcfg-eth1

vim /etc/sysconfig/network-scripts/ifcfg-eth1

DEVICE=eth0
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none


c) Load bond driver through modprobe.conf

vim /etc/modprobe.conf

alias bond0 bonding
options bond0 mode=balance-alb miimon=100


Manually load the bonding kernel driver to make it affective without server reboot:
 

modprobe bonding

d) Restart networking to load just configured bonding 
 

service network restart


3. Testing Bond Success / Fail status

Periodically if you have to administrate a bonded interface Linux server it is useful to check Bonds Link Status:

cat /proc/net/bonding/bond0
 

Ethernet Channel Bonding Driver: v3.5.0 (November 4, 2008)

Bonding Mode: fault-tolerance (active-backup)
Primary Slave: None
Currently Active Slave: eth0
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0

Slave Interface: eth0
MII Status: up
Link Failure Count: 0
Permanent HW addr: 00:1e:0b:d6:6c:8f

Slave Interface: eth1
MII Status: up
Link Failure Count: 0
Permanent HW addr: 00:1e:0b:d6:6c:8c

To check out which interfaces are bonded you can either use (on older Linux kernels)
 

/sbin/ifconfig -a


If ifconfig is not returning IP addresses / interfaces of teamed up eths, to check NICs / IPs:

/bin/ip a show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 brd 127.255.255.255 scope host lo
    inet 127.0.0.2/8 brd 127.255.255.255 scope host secondary lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond0 state UP qlen 1000
    link/ether 00:1e:0b:d6:6c:8c brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond0 state UP qlen 1000
    link/ether 00:1e:0b:d6:6c:8c brd ff:ff:ff:ff:ff:ff
7: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
    link/ether 00:1e:0b:d6:6c:8c brd ff:ff:ff:ff:ff:ff
    inet 10.239.15.173/27 brd 10.239.15.191 scope global bond0
    inet 10.239.15.181/27 brd 10.239.15.191 scope global secondary bond0:7156web
    inet6 fe80::21e:bff:fed6:6c8c/64 scope link
       valid_lft forever preferred_lft forever


In case of Bonding interface failure you will get output like:

Ethernet Channel Bonding Driver: v3.5.0 (November 4, 2008)
Bonding Mode: load balancing (round-robin)
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 200
Down Delay (ms): 200
Slave Interface: eth0
MII Status: up
Link Failure Count: 0
Permanent HW addr: 00:xx:yy:zz:tt:31
Slave Interface: eth1
MII Status: down
Link Failure Count: 1
Permanent HW addr: 00:xx:yy:zz:tt:30

Failure to start / stop bonding is also logged in /var/log/messages so its a good idea to check there too once launched:
 

tail -f /var/log/messages
Dec  15 07:18:15 nas01 kernel: [ 6271.468218] e1000e: eth1 NIC Link is Down
Dec 15 07:18:15 nas01 kernel: [ 6271.548027] bonding: bond0: link status down for interface eth1, disabling it in 200 ms.
Dec  15 07:18:15 nas01 kernel: [ 6271.748018] bonding: bond0: link status definitely down for interface eth1, disabling it

On bond failure you will get smthing like:

Dec  15 04:19:15 micah01 kernel: [ 6271.468218] e1000e: eth1 NIC Link is Down
Dec  15 04:19:15 micah01 kernel: [ 6271.548027] bonding: bond0: link status down for interface eth1, disabling it in 200 ms.
Dec  15 04:19:15 micah01 kernel: [ 6271.748018] bonding: bond0: link status definitely down for interface eth1, disabling it


4. Adding removing interfaces to the bond interactively
 

You can set the mode through sysfs virtual filesystem with:

echo active-backup > /sys/class/net/bond0/bonding/mode

If you want to try adding an ethernet interface to the bond, type:

echo +ethN > /sys/class/net/bond0/bonding/slaves

To remove an interface type:

echo -ethN > /sys/class/net/bond0/bonding/slaves


In case if you're wondering how many bonding devices you can have, well the "sky is the limit" you can have, it is only limited by the number of NIC cards Linux kernel / distro support and ofcourse how many physical NIC slots are on your server.

To monitor (in real time) adding  / removal of new ifaces to the bond use:
 

watch -n 1 ‘cat /proc/net.bonding/bond0′

 

Howto install GeoTrust RapidSSL certificate on Debian Lenny / Squeeze / Wheezy Linux

Thursday, March 25th, 2010

5 min read
I faced the task of generating official Validated SSL Certificates by in mydaily duties as a System Administrator at cadiaholding.com . Though generating self-signedSSL certificate is comparatively easy task. It was a pain in the ass setting Apache version 2.2.9-10+lenny6to correctly serve pages through https:// protocol over openssl version 0.9.8g-15+lenny6.I’ll try to go through the whole process of Generating the certificate in order to help some other Debianusers out there to face less setbacks in such a simple task as installing a Trusted SSL Certificate issued(bought) by RapidSSL. Even though this article will mostly deal with SSL certificate issued by RapidSSL,it should be not a problem to apply this methodogy with Verisign or some of the other Geotrust issuedSecure Socket Layer certificates.

In generating the Validated certficate I used enom which is a domain name,ssl certificates, email and hosting company whole-saler.
Fron emon’s website after logging in and using the web interface, there are two major things required to fill inin order to issue your Trusted SSL certificate.

1. Fill in in a form a CSR file, this is usually generated on the Linux server using the openssl.
To issue the CSR file required by Enom use the following commands:

a. First we generate an DES3 RSA encrypted key which we will use next to generate the opeensl CSR file required by ENOM.
debian:~# /usr/bin/openssl genrsa -des3 -out www.domain.com.key 2048
Enter pass phrase for www.domain.com.key:

You’ll be required to fill in a pass-phrase that will be later be required to fill in before Apache servers starts or restarts,so make sure you fill something you either remember or you keep the password stored in a file.
You have to change also the www.domain.com.key in accordance with your domain name.
Now as we already have a proper generated DES3 RSA key afterwards it’s necessery to generate the CSR file with the openssl command line frontend.
So here is how:

debian:~# /usr/bin/openssl req -new -key /home/hipo/www.domain.com.key -out /home/hipo/www.domain.com.csr

Again in the above example change all the paths and file names as you wish.
It’s necessery that the end user fill in a number of questions related to the Certificate Signing Request.
Herein I’ll list what kind of prompts will emerge after executing the above command:

Enter pass phrase for /home/hipo/www.domain.com.key:
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:
State or Province Name (full name) [Some-State]:
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:
Organizational Unit Name (eg, section) []:
Common Name (eg, YOUR name) []:
Email Address []:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

Note that you’ll hav eto fill in the pass phrase previously entered during the generation of the www.domain.com.key file.
In case if you’d like to read more thoroughly on the subject of howto create a Certificate Signing Request or (CSR) as we called it on multiple times, you can read About Certificate Signing Request (CSR) Generation Instructions – Apache SSL more in depth here

2. Hopefully following the above instructions you’ll now have a file named www.domain.csrJust open the www.domain.scr and copy paste it’s content to the ENOM website CSR * webform.

3. Further on select your Webserver type on Enom’s website:In our case we have to select Apache + ApacheSSL

4. What follows next is filling in your company contact information This is also required for proper certificate generation, you have to think twice before you fill in this data, take a note this can’t be changed later on without issuing a brand SSL new certificate.

Apart from the 3 major above requirements to fill in Enom there are some few more radio buttons to use to make some selections according to your personal preferences, however I won’t take time to dig in that and I’ll leave this to you.
After all the above is fulfilled you’ll have to submit your certificate details and choose an email address to which you will receive in a minute a RapidSSL Certificate Request Confirmation

Following a link from the email, will show you some basic information about the certificate about to be generated. That’s your final chance to cancel the issued Trusted Certificated.
If you’re absolutely sure the information about to enter the certificate is correct then you’ll have to follow a link and approve the certificate.

You’ll be informed that you’ll receive your certificate either through Certifier website (e.g. Enom’s website) or via another email.
I thought it’s more probable I receive it via email but anyways I was wrong. More thank 4 hours has passed since the certificate was issued and is available via Enom’s interface but I haven’t received nothing on my mail.
Therefore my friendly advice is to check about your brand new shiny Trusted Certificate on Emom’s website. I had mine ready in about 10 minutes after the CSR was issued.

Assuming that you’ve succesfully obtained the SSL Trusted certificate from RapidSSL what follows is setting up the certificate.
Initially I tried using documentation from RapidSSL website called Installing your SSL Certificate / Web Server Certificate / Secure Server Certificate from RapidSSL.com
I tried to configure one of my Virtualhost as shown in their example inserting in my /etc/apache/sites-available/www.domain.com file, few directives within the VirtualHost something like the shown below

SSLEngine on
# domain.com.crt cointains the Trusted SSL certificate generated and obtained by you from RapidSSL
SSLCertificateFile /etc/apache2/ssl/www.domain.com.crt
# www.domain.com.key contains the file used to generate the CSR file as described earlier in this post
SSLCertificateKeyFile /etc/apache2/ssl/www.domain.com.key

It is also possible insetad of using the SSLCertificateFile and SSLCertificateKeyFile directvies directives in Apache config to use:

 

Another alternative is to use

SSLCertificateFile /etc/ssl/certs/your-domain-name.crt
SSLCertificateKeyFile /etc/ssl/certs/your-domain-name.key
SSLCACertificateFile /etc/ssl/certs/gd_bundle.crt

The key file is the one generated earlier on the server and handed to the SSL regisrar, the files:

your-domain-name.crt and gd_bundle.crt files are provided by RapidSSL or from whatever SSL registrater the SSL was purchased.

After trying the above configuration and restarting apache with:

/etc/init.d/apache2 restart

Apache failed to start, it might be helpful to somebody out there the error I had in my apache error.log:
The error.log red the following:

[warn] RSA server certificate is a CA certificate (BasicConstraints: CA == TRUE !?)

After some 30 minutes or an hour of Googling on the error I came to the conclusion that the error is caused, becauseApache is supposed to work with .PEM files instead of the classical .CRT and .KEY files asnormally approached in most of the other Unix operating systems.

It took me a bit more of reading on the internet to find out that actually the .pem files so widely adopted in Debian simply contain both the www.domain.com.key file and the www.domain.com.crt key simply pasted one after another, this I also observed from the default Apache self-signed certificate that I believe comes with debian /etc/apache2/ssl/apache.pem .
So I copied both the content of my www.domain.com.key and www.domain.com.crt and store it in one file:
/etc/apache2/ssl/www.domain.com.pem

Also the following configuration:
SSLEngine on
SSLCertificateFile /etc/apache2/ssl/www.domain.com.pem

had to go in your
/etc/apache2/sites-enabled/www.domain.com

Last thing that’s left is to restart your Apache;

/etc/init.d/apache2 restart

Apache will prompt you for your certificate password entered by you during the www.domain.com.key generation. Type your password and with a bit of luck and hopefully with God’s help you’ll be having a Trusted Certificate on your webserver.

Last step is to check if the certificate is okay accessing your domain https://www.domain.com.

Well this is the end of the article, hope you enjoy.If you do please leave your comments, any corrections are also welcomed 🙂