Sunday, July 28, 2013

Linux IPSec VPN-2: Amazon Cloud Sever & Linksys Router

This is a post in response to a comment made earlier on my previous blog post on Linux IPSec Setup asking for assistance. So here's what I could possibly do to help the needy.

This is a setup which I assisted one of my friend in creating a VPN between a Static IP Linksys Router and an Amazon cloud based server. Since we all know that Amazon cloud servers don't actually have a static public IP assigned to them instead they've a One-to-One NAT mechanism at the best so this becomes a bit trickier for anyone new to the OpenSWAN or IPSec in Linuxes.

Regardless of the Operating System the openswan package needs to be installed on the server properly. Please refer to other blogs or Google in order to install ipsec service. See this references in this link:

The topology we'll be working on is defined in the diagram below.

Now get to the configurations.

The ipsec.conf file contains these:

config setup
conn Linksys

And ipsec.secrets contains this: : PSK  "y0ur_S3cret_PSK_k3y"

Lets quickly get to the Linksys router and adjust the router according to the following settings.

Move to the VPN tab after logging in to the Linksys router.

Save the settings and restart vpn on both ends. Your VPN should start rocking by now. Ping from the LAN to the Amazon IPSec Server's Private IP and it should be replying.

Please always read logs on both the router and the linux server very carefully and figure out what they are trying to communicate. Without any logs I probably would never had created this VPN.

I hope it be of some help to someone. Have a great day.

Wednesday, July 24, 2013

NIC Bonding in CentOS 6.4,Ubuntu 12.04, and Vyatta 6.6

Its late night here and unexpectedly I'm high on motivation to do something except working hence just shifting my procrastination energy into writing this blog.

I've previously blogged a post on setting up an Active/Passive HA setup for Linux servers, so this on is one step further into one server. By one step further into the server I mean to have some form of High Availability on Network Interfaces.

Link Aggregation, NIC Bonding, NIC teaming, Interface Bonding are various names it is known as. Read some basics on it visit this wikipedia link.

My basic motivation for creating NIC Bonding on my servers was to create a self healing topology in which a single cable or interface failure do not impact any service at all. Since I've redundant powers, servers, switches, and routers setup from my very own hands so I know how this will add up in my setup. Removing one cable from the server keeps the server accessible and hence all services working perfectly fine.

The additional benefit which I can benefit from NIC bonding is link "Aggregation". The two 1Gbps interface will and can combine to give me an aggregated speed of 2Gbps. That is something I still need to test and probably post my findings on its reality sometime by transferring huge chunks of data.

WARNING: I had to reboot one of my server as I had an interface already configured so a service restart didn't work properly and the same IP remained configured on eth0 and bond0 and hence caused temporary access issue. Just to be sure have a KVM/ILOM remote access ready while doing this setup.

Lets move forward.

Creating NIC Bond interface on CentOS 6.4

[root@ASTERISK-A ~]# vim /etc/sysconfig/network-scripts/ifcfg-bond0

and insert the following fairly simple to understand lines.


Now remember, we need to have atleast two NIC present on the server to be part of the bond. This could be three Gig Interfaces if you've them available in order to achieve a 3Gbps link.

Edit the Interfaces going to be part of this bond.

[root@ASTERISK-A ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0


[root@ASTERISK-A ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth1


Now its time to setup some parameters for the 007-Bond Interface.

[root@ASTERISK-A ~]# vim /etc/modprobe.d/bonding.conf

Write the lines below in the file,save and exit.
alias bond0 bonding
options bond0 mode=1 miimon=100 arp_interval=100 arp_ip_target=,,

The above configuration is used by the "bonding" Linux kernel module. The options are important here:

mode=1 : Set the bonding method to Active backup
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.
arp_interval=100 : Set the ARP link monitoring frequency to 100 milliseconds (You can setup any keeping your network equipment in mind). This is important to be there.
arp_ip_target=, : Use the (router ip) and 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.

Thats all. Just restart the networking service and if you've any ethernet interface configured then you might need to shutdown that interface and start the network service again.

[root@ASTERISK-A ~]# /etc/init.d/network restart

Creating NIC Bond interface on Ubuntu 12.04

On Ubuntu Server the steps for configuring are 90% the same except that we need to install the package which gets the bonding kernel module.

root@OpenSIPS-A:~# apt-get install ifenslave

We just need to edit one file here.

root@OpenSIPS-A:~# vim /etc/network/interfaces

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet manual
        bond-master bond0

auto eth1
iface eth1 inet manual
        bond-master bond0

auto bond0
iface bond0 inet static
mtu 9000
        bond-miimon 100
        bond-downdelay 200
        bond-updelay 200
        bond-mode active-backup
        bond-slaves none

To make sure that the bonding kernel module is loaded on reboots edit the file /etc/modules
add the word "bonding" at the end save, and exit. To Load bonding module right away execute the following command:

root@OpenSIPS-A:~# modprobe bonding

Now restart the networking service and bond0 interface should be up and ready. 

root@OpenSIPS-A:~# /etc/init.d/networking restart

             Creating NIC Bond interface on Vyatta 6.6

Vyatta is one of my favorite subject, huge thanks to Mr. Asim Ansari who introduced me to it back in 2010 and I've been using it and loving it ever since. There are other cool stuff Vyatta is doing for me which I'll cover later on. Lets see how to create a Bond Interface on Vyatta.

vyatta@FW-A:~$ configure
vyatta@FW-A# set interfaces bonding bond0 address
vyatta@FW-A# set interfaces bonding bond0 arp-monitor interval 100
vyatta@FW-A# set interfaces bonding bond0 mode adaptive-load-balance
vyatta@FW-A# set interfaces bonding bond0 mtu 9000
vyatta@FW-A# set interfaces ethernet eth0 bond-group bond0
vyatta@FW-A# set interfaces ethernet eth1 bond-group bond0
vyatta@FW-A# commit
vyatta@FW-A# save

WARNING: Once again ensure that the eth0 and eth1 are not assigned with IP address already, if so please delete them before assigning that ethX interface to bond-group. 

Thats all for tonight, I'm sleepy now and should take rest while you guys enjoy having good time with your servers and setups.

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