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redhat 5.2 traceroute concerns

akaltz asked
I have a machine with Red Hat 5.2 that is multi-homed on several different networks. My question is
regarding the traceroute command. Even if you specify an interface using -i, it stills seems to pick
a randomly select interaface to send packets out. Has anybody experienced this before or know of a
traceroute patch or command that I may not be previewed to? I am trying to troubleshoot a routing issue
on this is making it a bit difficult. Also, if you are aware of a site or doc that can provide information
on how Linux (or unix in general) supports networking on multi-homed machines so I can re-check my understanding
that would be great as well.

Watch Question


how do you check which interface it uses?
traceroute uses the interface which needs to be used according to the routing table, usually.
Sorry I don't have RH's traceroute, but mine does not have the -i option.


I check which interface to use by looking at the route table.  The -i option specifies the interface you want to send traceroute out of for the test.  For example, if I traceroute to a public address and specify the address it is suppose to go to, it says there are multiple interfaces then uses an interface for a private address, not taking into account the route table.
ok, you say that for example
   traceroute -i eth0
does not use the IP of eth0 (which it should according to the man-page). Have you tried:
   traceroute -s aa.bb.cc.dd
where aa.bb.cc.dd is the IP you want to use as the source?

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