On a multihomed Linux machine, how can I find out what network interface will be used to send a packet to a specific host? I need to do this programmatically and I'd rather not parse and interpret the routing table myself.
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That's what routing table is for. I don't imagine it otherwise.– GioMacAug 17, 2013 at 18:02
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3 Answers
Use ip route for this. For instance:
ip route show to match 198.252.206.16
answered Aug 17, 2013 at 18:03
Shorter option:
ip route get 172.29.42.94
Yes, as Michael Hampton suggests, use ip route. If you only want the interface, use this
ip -o route get $ip | perl -nle 'if ( /dev\s+(\S+)/ ) {print $1}'
For example:
# ip=8.8.8.8
# iface=$( ip -o route get $ip | perl -nle 'if ( /dev\s+(\S+)/ ) {print $1}' )
# echo $iface
eth1
