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Accepted
Kevin Campion
Asked: 2010-05-17 08:38:46 +0800 CST

Change OpenVZ route to pass through ip failover

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I have one dedicaced server with its own IP and another IP (failover) who refer to the first.

I will wish to change the gateway of a Proxmox virtual machine (openvz) who runs on this dedicaced server to go through the failover IP rather than the ip of host main server.

Once connected to a virtual machine, when I do a traceroute

VE# traceroute www.google.fr

traceroute to www.google.fr (209.85.229.104), 30 hops max, 60 byte packets
 1  MY_SERVER_NAME.ovh.net (xxx.xxx.xxx.xxx FIRST_IP_MAIN_SERVER)  0.021 ms  0.010 ms  0.009 ms

The first line tells me the ip of host main server. I would like that the traceroute display the second IP failover.

VE# route

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.0.2.1       *               255.255.255.255 UH    0      0        0 venet0
default         192.0.2.1       0.0.0.0         UG    0      0        0 venet0

With iptables

HOST# iptables -t nat -L

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination         
MASQUERADE  all  --  anywhere             anywhere            
MASQUERADE  all  --  anywhere             anywhere            
SNAT       tcp  --  anywhere             10.10.101.2         tcp dpt:www state NEW,RELATED,ESTABLISHED,UNTRACKED to:SECOND_IP_FAILOVER
SNAT       all  --  10.10.101.2          anywhere            to:SECOND_IP_FAILOVER

10.10.101.2 is the virtual machine IP (interface venet0)

Any ideas ?

networking iptables failover route

1 Answers

  1. Best Answer

    I'm not quite sure if I understand you correctly, but maybe source based routing is what you want?

    Basically you do the following:

    ip rule add from 10.10.101.2 table 42
ip route add 10.10.101.2/24 dev eth0 table 42
ip route add default dev eth0 via $gateway table 42

    Instead of the table identifier 42 you can pick any number (or symbolic name, if you map them via /etc/iproute2/rt_tables), but some are reserved.

    Your configuration is probably a bit different, I don't know your gateway for example and guessed the netmask.

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