Learning while building a site-to-site VPN

So many things that I still learn. One important piece is to learn the theory, and another completely different matter is to apply this knowledge into practice, which turns into wisdom.

I´m speaking about building a site-to-site VPN. I started trying with IPSec but decided to use a known solution by my friend Gabriel Orozco (aka @Redimido) helped me out with this setup.

So far what I´ve learned from this exercise was:

• You only need to enable a OpenVPN server on one of your subnets and a OpenVPN client on the other side of your subnets
• Windows will treat any 169.254.XXX.XXX as a failed DHCP lease and hence won´t work at all
• Your netmask is pretty important, because if using a 16 bit (class B network) the requests sent from a machine inside a subnet won´t reach the default gateway and hence no communication is possible between the two subnets using the VPN

Also, thanks a lot to my friend Galileo Martínez that taked lot of ownership when helping me out to debug the issue between the 20 and 10 subnets. 

I owe you both a lot of time. 

What is DPDK about?

Before a couple of months ago I was not aware of a new technology called DPDK intended to accelerate packet processing on common commodity servers. Instead of running propietary hardware with high cost licenses DPDK allow a very modest server to process 24x the amount of packets compared to a single core network appliance. It use an source BSD license.

A brief and easy 4 minutes explanation of DPDK can be found on the following video:


Next just for fun experiment would be to build a virtualized DPDK appliance under openstack.

wicked: device ib0 failed: operation timed out

Just to mention that when trying to start an InfiniBand ib0 interface without the opensm-3.3.17-5.7.x86_64.rpm package on SLES12 will throw you the following message:

wicked: device ib0 failed: operation timed out

Make sure you have package opensm-3.3.17-5.7.x86_64.rpm installed and then issue:

/etc/init.d/opensmd start 

in order to:

ifup ib0

Comments are welcome.