I have a machine with eth1 IP 10.3.1.4 and eth2 with 10.3.2.4
I am using source-based routing, and have the eth1 & 2 ports connected
to another machine which is acting as a route (the other machine has 10.3.1.1
and 10.3.2.1
IP addresses).
I run ping with the -I option to bind it to eth1, but instead of sending
the arp and/or ICMP request to the gateway, it instead arps for the IP on
eth2.
The machines are running RedHat 9, and the problem exists in the
default 2.4.20-8 kernel. I have not tried other kernels yet, so if you
think this is a RedHat only issue, I can try the stock kernel.
Here is the output from the machine that is attempting to send the traffic:
[root@localhost root]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:03:47:2B:39:CA
inet addr:192.168.1.22 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1362 errors:0 dropped:0 overruns:0 frame:0
TX packets:1345 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:80208 (78.3 Kb) TX bytes:1705206 (1.6 Mb)
Interrupt:11 Base address:0xdf00 Memory:feafe000-feafe038
eth1 Link encap:Ethernet HWaddr 00:03:47:2B:39:CB
inet addr:10.3.1.4 Bcast:10.3.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:8 errors:0 dropped:0 overruns:0 frame:0
TX packets:377 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:400
RX bytes:596 (596.0 b) TX bytes:16338 (15.9 Kb)
Interrupt:11 Base address:0xde80 Memory:feafd000-feafd038
eth2 Link encap:Ethernet HWaddr 00:50:C2:11:32:64
inet addr:10.3.2.4 Bcast:10.3.2.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:3 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:11 Base address:0xbc00
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:1418 errors:0 dropped:0 overruns:0 frame:0
TX packets:1418 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1938073 (1.8 Mb) TX bytes:1938073 (1.8 Mb)
[root@localhost root]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
10.3.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
10.3.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth2
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 192.168.1.5 0.0.0.0 UG 0 0 0 eth0
[root@localhost root]# ip ru
0: from all lookup local
32758: from 10.3.2.4 lookup 2
32759: from 10.3.1.4 lookup 1
32766: from all lookup main
32767: from all lookup 253
[root@localhost root]# ip route show table 1
10.3.1.0/24 via 10.3.1.4 dev eth1
default via 10.3.1.1 dev eth1
[root@localhost root]# ip route show table 2
10.3.2.0/24 via 10.3.2.4 dev eth2
default via 10.3.2.1 dev eth2
[root@localhost root]# ping -I eth1 10.3.1.1
PING 10.3.1.1 (10.3.1.1) from 10.3.1.4 eth1: 56(84) bytes of data.
64 bytes from 10.3.1.1: icmp_seq=1 ttl=64 time=0.167 ms
64 bytes from 10.3.1.1: icmp_seq=2 ttl=64 time=0.087 ms
# The other interface on the router machine (same machine as I just pinged
above)
[root@localhost root]# ping -I eth1 10.3.2.1
PING 10.3.2.1 (10.3.2.1) from 10.3.1.4 eth1: 56(84) bytes of data.
From 10.3.1.4 icmp_seq=1 Destination Host Unreachable
From 10.3.1.4 icmp_seq=3 Destination Host Unreachable
# It is NOT using the default gateway for this traffic, but is instead
# just trying to ARP.
[root@localhost root]# tcpdump -n -i eth1
tcpdump: listening on eth1
11:56:19.788336 arp who-has 10.3.2.1 tell 10.3.1.4
11:56:20.788134 arp who-has 10.3.2.1 tell 10.3.1.4
11:56:21.788149 arp who-has 10.3.2.1 tell 10.3.1.4
11:56:22.788379 arp who-has 10.3.2.1 tell 10.3.1.4
--
Ben Greear <greearb@xxxxxxxxxxxxxxx> <Ben_Greear AT excite.com>
President of Candela Technologies Inc http://www.candelatech.com
ScryMUD: http://scry.wanfear.com http://scry.wanfear.com/~greear
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