ping -I is broken The following deals with bug in ping that made it very difficult to set up a system with two gateways. Demonstration that *ping -I is broken*. When specifying the source interface using -I with an *ethX* alias and that interface is not the default gateway interface, then ping fails. When specifying the interface as an ip address, ping works. Search for "Destination Host Unreachable" to find the bug. eth*0* = 4.3.2.8 and the default gateway is accessed through a different interface eth*1*. eth*1* = 192.168.168.155 is used as the device to get to the default gateway. *FAILS *: ping *-I eth0* 208.67.222.222 *WORKS*: ping *-I 4.3.2.8* 208.67.222.222 *WORKS*: ping *-I eth1* 208.67.222.222 *WORKS*: ping *-I 192.168.168.155* 208.67.222.222 The following are actual results which can be reproduced from an up-to-date Fedora 11 or CentOS 5.3 box. Caused a very very long episode of frustration when setting up multi gatewayed systems. * ping using eth0 *: ping -c 2 -B -I eth0 208.67.222.222 PING 208.67.222.222 (208.67.222.222) from 4.3.2.8 eth0: 56(84) bytes of data. >From 4.3.2.8 icmp_seq=1 Destination Host Unreachable >From 4.3.2.8 icmp_seq=2 Destination Host Unreachable --- 208.67.222.222 ping statistics --- 2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 999ms , pipe 2 -------------------------------------- The Following all WORK: * ping using 4.3.2.8 *: ping -c 2 -B -I 4.3.2.8 208.67.222.222 PING 208.67.222.222 (208.67.222.222) from 4.3.2.8 : 56(84) bytes of data. 64 bytes from 208.67.222.222: icmp_seq=1 ttl=55 time=562 ms 64 bytes from 208.67.222.222: icmp_seq=2 ttl=55 time=642 ms --- 208.67.222.222 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 999ms rtt min/avg/max/mdev = 562.546/602.400/642.255/39.862 ms * ping using eth1 *: ping -c 2 -B -I eth1 208.67.222.222 PING 208.67.222.222 (208.67.222.222) from 192.168.168.155 eth1: 56(84) bytes of data. 64 bytes from 208.67.222.222: icmp_seq=1 ttl=54 time=270 ms 64 bytes from 208.67.222.222: icmp_seq=2 ttl=54 time=629 ms --- 208.67.222.222 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1000ms rtt min/avg/max/mdev = 270.128/449.766/629.405/179.639 ms * ping using 192.168.168.155 *: ping -c 2 -B -I 192.168.168.155 208.67.222.222 PING 208.67.222.222 (208.67.222.222) from 192.168.168.155 : 56(84) bytes of data. 64 bytes from 208.67.222.222: icmp_seq=1 ttl=54 time=585 ms 64 bytes from 208.67.222.222: icmp_seq=2 ttl=54 time=554 ms --- 208.67.222.222 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 999ms rtt min/avg/max/mdev = 554.098/569.655/585.212/15.557 ms My source route policy rules: /sbin/ip rule show 0: from all lookup 255 32762: from 4.3.2.8 lookup nic0 32763: from 192.168.168.155 lookup nic1 32764: from 192.168.168.155 lookup nic1 32765: from 4.3.2.8 lookup nic0 32766: from all lookup main 32767: from all lookup default Print out routing tables using /sbin/ip route show table TABLENAME: routing table nic0 : /sbin/ip route show table nic0 default via 4.3.2.1 dev eth0 routing table nic1 : /sbin/ip route show table nic1 default via 192.168.168.1 dev eth1 routing table main : /sbin/ip route show table main 4.3.2.1/27 dev eth0 proto kernel scope link src 4.3.2.8 192.168.168.0/24 dev eth1 proto kernel scope link src 192.168.168.155 169.254.0.0/16 dev eth1 scope link default via 192.168.168.1 dev eth1 routing table default : /sbin/ip route show table default NOTES: cat /etc/iproute2/rt_tables to get your own table names. ping Maintainer YOSHIFUJI Hideaki / USAGI/WIDE Project http://www.skbuff.net/iputils/ Mailing List netdev at vger.kernel.org man ping: -I interface address Set source address to specified interface address. Argument may be *numeric IP address or name of device*. When pinging IPv6 link-local address this option is required. ping -V returns the latest available on CentOS and Fedora and the maintainers website: ping utility, iputils-ss020927