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Accepted
Rob H
Asked: 2013-08-18 09:58:46 +0800 CST

Find interface for route to specific host

  • 772

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.

linux

3 Answers

  1. Best Answer

    Use ip route for this. For instance:

    ip route show to match 198.252.206.16
    • 44

  2. Shorter option:

    ip route get 172.29.42.94
    • 25

  3. 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
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