routing problem with outgoing traffic

vivhost · 03-30-2009, 02:55 PM

Hello, I've been trying to research this, but I don't really understand IP routing and it's bugging me that I can't fix this problem. I have a dedicated server (fedora core 7) with 3 IP addresses on the same eth0 interface. On the default IP address 62.193.226.127, there is some routing problem because I can't connect from the server to some other sites. Using one of the other IP addresses, like 62.193.252.129, I can connect fine (for example, using wget --bind-address=62.193.252.129 ...) Additionally this address is better for sending mail because it coincides with the main domain name from which the mail is sent.

My main question is: how can I configure networking so that outgoing traffic from the box goes via 62.193.252.129 as source IP?

Here is some info:

eth0 Link encap:Ethernet HWaddr 00:18:37:09:99:87
inet addr:62.193.226.127 Bcast:62.193.227.255 Mask:255.255.252.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:155048 errors:0 dropped:0 overruns:0 frame:0
TX packets:189356 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:32241110 (30.7 MiB) TX bytes:218707677 (208.5 MiB)
Interrupt:5 Base address:0xc000

eth0:1 Link encap:Ethernet HWaddr 00:18:37:09:99:87
inet addr:62.193.252.129 Bcast:62.193.252.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:5 Base address:0xc000

eth0:2 Link encap:Ethernet HWaddr 00:18:37:09:99:87
inet addr:62.193.252.147 Bcast:62.193.252.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:5 Base address:0xc000

Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
62.193.252.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
62.193.224.0 0.0.0.0 255.255.252.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
0.0.0.0 62.193.227.254 0.0.0.0 UG 0 0 0 eth0

kenoshi · 03-30-2009, 08:17 PM

Change the device used for the default route. For example (make sure you do this from console):

Code:

route del default
route add default gw <gateway IP here> dev eth1

And make changes to your network files as follows:

- In /etc/sysconfig/network, delete the GATEWAY= line
- In /etc/sysconfig/network-scripts/ifcfg-eth1, add

GATEWAY=<gateway IP here>

Hope this helps.

vivhost · 03-31-2009, 08:53 AM

OK, but I don't have an eth1... just eth0 with 3 IP addresses. So, should it be:

route del default
route add default gw 62.193.227.254 dev eth0:1

and then edit the /etc/sysconfig/network-scripts/ifcfg-eth0:1? and REMOVE the gateway from /etc/sysconfig/network?
Thanks