[CentOS] routing with 2 public ips

Sun Dec 27 04:16:45 UTC 2015
Eliezer Croitoru <eliezer at ngtech.co.il>

This is half true.
Depends on the application or the way that the network traffic is 
flowing you could use some iptables rules to mark a connection for 
example by the source MAC address per new connections which would be a 
specific router and by that mark the connection, then in the routing 
level decide which default gateway to use for this specific connection.
You can take a look at an example that I wrote and modify it to use a 
MAC address match instead of NFQUEUE at:

The idea is that you mark a new connection from a specific router with a 
unique mark and then restore the connection mark to force a specific 
routing table on this mark(IE connection)

Hope it Helps,

On 25/12/2015 22:28, Paul R. Ganci wrote:
> On 12/25/2015 12:44 PM, Joey wrote:
>> i have a server with 2 public ips on 2 devices.
>> I want that the request of incoming traffic dont use the default
>> gateway. Incoming traffic sould be answered using the gateway of the
>> incoming device
>> Could i realize this with firewalld? Or directly iptables?
> No you can not do that via firewalld or iptables. The problem is you
> have to tell the packets to go out the proper interface which must be
> done via routing tables. For that purpose you need ip route. I suggest
> you take a look at
> https://kindlund.wordpress.com/2007/11/19/configuring-multiple-default-routes-in-linux/
> This link provides a very thorough description of what must be done.
> Just a warning is that you will want your routing tables to be
> maintained across system boots. I put my routes for my bridged
> interfaces into:
> /etc/sysconfig/network-scripts/route-br1
> /etc/sysconfig/network-scripts/route-br2
> You can put your routes into similar files... just replace the br1/br2
> with your appropriate interface names.