I am having the damnedest time with a dual-IP CentOS5-based appliance
which seems to defy its iproute2 configuration, and I'm here hoping
someone smarter than me (admittedly not a high bar) might be so kind as
to tell me what I'm missing:
# ip route show table main
10.1.1.1 dev tun0 proto kernel scope link src 10.1.1.7
10.250.32.1 via 10.1.1.1 dev tun0
10.250.10.0/24 via 10.1.1.1 dev tun0
192.168.25.0/24 dev eth0 proto kernel scope link src 192.168.25.124
192.168.25.0/24 dev eth1 proto kernel scope link src 192.168.25.100
default via 192.168.25.1 dev eth1
default via 192.168.25.1 dev eth0
# ip route get 8.8.8.8
8.8.8.8 via 192.168.25.1 dev eth0 src 192.168.25.124
cache mtu 1500 advmss 1460 hoplimit 64
I have been playing with this box for several days, and no matter what I
do (including reboots) it wants to route almost everything out eth0
instead of eth1, despite the ordering of default routes shown above
which should see eth1 taking precedence. No iptables
PREROUTING/nat/mangle/raw stuff, this is all straight iproute2.
I determined that the 'main' table was the one at issue by inserting and
removing an overriding rule at various priorities to see when 'ip get'
would change behavior:
# ip rule show | tail
32758: from all to 192.168.72.0/24 lookup defroutes
32759: from 192.168.72.0/24 lookup defroutes
32760: from 192.168.72.0/24 lookup mgtroutes
32766: from all lookup main
32767: from all lookup default
# ip route add table custom to 8.8.8.0/24 via 192.168.72.1 dev eth1 src 192.168.72.100
# for i in $(seq 32767 -1 32764); do ip rule add prio $i to 8.8.8.0/24 lookup custom; ip route flush cache; sleep 2; echo -en "$i:\t"; ip route get 8.8.8.8| head -1; ip rule del prio $i to 8.8.8.0/24 lookup custom; ip route flush cache; sleep 2; done
32767: 8.8.8.8 via 192.168.72.1 dev eth0 src 192.168.72.124
32766: 8.8.8.8 via 192.168.72.1 dev eth0 src 192.168.72.124
32765: 8.8.8.8 via 192.168.72.1 dev eth1 src 192.168.72.100
32764: 8.8.8.8 via 192.168.72.1 dev eth1 src 192.168.72.100
Both interfaces are up, and are *able* to reach 8.8.8.8 via the upstream
gw:
# ping -c 1 -I eth0 8.8.8.8
PING 8.8.8.8 (8.8.8.8) from 192.168.72.124 eth0: 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=47 time=14.9 ms
--- 8.8.8.8 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 14.990/14.990/14.990/0.000 ms
# ping -c 1 -I eth1 8.8.8.8
PING 8.8.8.8 (8.8.8.8) from 192.168.72.100 eth1: 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=47 time=14.9 ms
--- 8.8.8.8 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 14.999/14.999/14.999/0.000 ms
Can anyone help my figure out why this box (alone out of many, many
appliances with similar configurations at various customer sites) is
determined to reach out through eth0?
The full RPDB ruleset:
# ip rule show
0: from all lookup 255
10: from all lookup bootstrap
32736: from all to 128.119.40.1 lookup mgtroutes
32737: from all to 192.168.126.228 lookup mgtroutes
32738: from all to 192.168.76.232 lookup mgtroutes
32739: from all to 192.168.90.112 lookup mgtroutes
32740: from all to 192.168.61.112 lookup mgtroutes
32741: from all to 192.168.76.232 lookup mgtroutes
32742: from all to 192.168.61.112 lookup mgtroutes
32743: from all to 192.168.34.35 lookup mgtroutes
32744: from all to 192.168.61.112 lookup defroutes
32745: from all to 192.168.134.47 lookup mgtroutes
32746: from all to 192.168.127.68 lookup mgtroutes
32747: from all to 192.168.66.6 lookup mgtroutes
32748: from all to 192.168.126.228 lookup mgtroutes
32749: from all to 192.168.127.68 lookup mgtroutes
32750: from all to 192.168.134.41 lookup mgtroutes
32751: from all to 192.168.134.41 lookup mgtroutes
32752: from all to 192.168.76.232 lookup mgtroutes
32753: from all to 107.23.15.175 lookup mgtroutes
32754: from all to 216.87.69.94 lookup mgtroutes
32755: from 192.168.72.124 lookup mgtroutes
32756: from 192.168.72.100 lookup defroutes
32757: from 192.168.72.0/24 to 192.168.72.0/24 lookup mgtroutes
32758: from all to 192.168.72.0/24 lookup defroutes
32759: from 192.168.72.0/24 lookup defroutes
32760: from 192.168.72.0/24 lookup mgtroutes
32766: from all lookup main
32767: from all lookup default
Thank you for any clue you can spare,
Ole
--
Ole Craig <olc@xxxxxxxxxxxxxxxxxxx>
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