Frank Cox wrote: > I have dealt with machines that have multiple network cards in them > before, but never when they were on the same subnet so this issue has > never come up before. > > My problem is that I can only access one IP address at a time. I > started out using dhcp and found that if I went through the dhcp > song-and-dance then that address became active and the other one was > disabled, and vice versa. > > On our local tech mailing list, a couple of the guys advised me that > this is due to a routing issue and, after a bit of googling around I now > understand why that is. > > However, I have so far been unable to fix it. > > I got rid of dhcp and set up static addresses using > system-config-network. > > This machine has three network cards in it, eth0 is 192.168.1.5 and I > use that one to ssh into the box from this computer. (I really don't > want to lose my ability to connect to eth0; this machine runs headless > on a shelf about 7 feet above the floor and it would be quite an > undertaking to dismantle it and bring it down to hook a monitor and > keyboard to it again.) > > The solution to this problem appears to be easier to describe than to > implement, at least for me. I need to have each network card reply back > on the same interface that it received a request from. > > eth1 is 24.89.92.178 > eth2 is 24.89.92.180 > > The gateway for both of these is 24.89.92.1 > > The suggestion that I got was to add two entries to the end > of /etc/iproute2/rt_tables (which I did with a text editor) and run a > series of ip route commands which set up a custom routing table but I'm > missing something because while the custom routing tables appear to be > getting set up, it's still not working. > > I have studied the suggested routing commands and I think I understand > what they are doing and what is supposed to be happening. But something > is still missing because it's not working. > > Here is what I did and what the results are. If I have missed anything > let me know; this covers what I think is the relevant information as I > currently understand it. I would sincerely appreciate any further > advice regarding this situation. I really would like to know what I am > doing wrong and also why (in the interest of learning something from > this situation). It's new territory for me. > > [root at audio ~]# cat /etc/iproute2/rt_tables > # > # reserved values > # > 255 local > 254 main > 253 default > 0 unspec > # > # local > # > #1 inr.ruhep > 50 access1 > 60 access2 > [root at audio ~]# ip route add 24.89.92.0/24 dev eth1 table access1 > [root at audio ~]# ip route add default via 24.89.92.1 table access1 > [root at audio ~]# ip rule add from 24.89.92.178/32 lookup access1 > [root at audio ~]# > [root at audio ~]# ip route add 24.89.92.0/24 dev eth2 table access2 > [root at audio ~]# ip route add default via 24.89.92.1 table access2 > [root at audio ~]# ip rule add from 24.89.92.180/32 lookup access2 > [root at audio ~]# ip route show table access2 > 24.89.92.0/24 dev eth2 scope link > default via 24.89.92.1 dev eth1 > [root at audio ~]# ip route show table access1 > 24.89.92.0/24 dev eth1 scope link > default via 24.89.92.1 dev eth1 > [root at audio ~]# ip route > 24.89.92.0/24 dev eth1 proto kernel scope link src 24.89.92.178 > 24.89.92.0/24 dev eth2 proto kernel scope link src 24.89.92.180 > 192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.5 > 169.254.0.0/16 dev eth2 scope link > default via 24.89.92.1 dev eth1 > > [frankcox at mutt ~]$ ping 24.89.92.178 > PING 24.89.92.178 (24.89.92.178) 56(84) bytes of data. > 64 bytes from 24.89.92.178: icmp_seq=1 ttl=50 time=92.2 ms > 64 bytes from 24.89.92.178: icmp_seq=2 ttl=50 time=96.2 ms > 64 bytes from 24.89.92.178: icmp_seq=3 ttl=50 time=91.0 ms > > --- 24.89.92.178 ping statistics --- > 3 packets transmitted, 3 received, 0% packet loss, time 2001ms > rtt min/avg/max/mdev = 91.023/93.193/96.263/2.245 ms > [frankcox at mutt ~]$ ping 24.89.92.180 > PING 24.89.92.180 (24.89.92.180) 56(84) bytes of data. > > --- 24.89.92.180 ping statistics --- > 6 packets transmitted, 0 received, 100% packet loss, time 5000ms > > Incidentally, it is my current understanding that anything that I do > with an "ip route" command will go away on a reboot, therefore if I > somehow screw up the routing on this box completely all I have to do is > reboot it and I'll be back to what I had before. Which is not a bad > thing at the moment. Once I have this nailed down should I put the "ip > route" commands into /etc/rc.local? Or is there a better place? > > > Hi This Article should be exactly what you need http://www.linuxjournal.com/node/7291/print