[CentOS] how to force outbound ssh through one network card

Wed Mar 9 03:41:43 UTC 2016
Gregory P. Ennis <PoMec at PoMec.Net>

Everyone,

I am putting together a new gateway machine that controls all of the
traffic in and out of one of our offices.  We we have a machine with
CentOS Linux release 7.2.1511 (Core)  with 3.10.0-327.10.1.el7.x86_64
kernel which is now equipped with three nic cards.   We decided to
change our internet providers, but unfortunately Comcast would not
allow us to drop there service without some penalties so management
decided to keep the line and not put up a fight. Of the three nic
cards, one card serves the local network inside the office, and the
other two will connect to the two different internet lines.   

This has resulted in providing us with two outbound internet lines that
we can use.  I decided to do some experimenting to see if I could use
iptables or other venues to use both outside internet addresses to
augment our bandwidth.  

Can anyone refer me to any tutorial or give me suggestions as to how to
route outbound ssh traffic that is generated from one of the machines
inside the network through only one of the specified nic cards on the
gateway.  I would like to see if I can utilize this extra band width by
splitting ssh traffic and html traffic.  Essentially, I would like to
force outbound ssh traffic on only one of the outside nic cards.

Any ideas?

Greg Ennis