Linux list the outgoing interface for packets to a specific IP destination

To be able to get the outgoing interface for traffic to a specific destination, the iproute package needs to be installed:

Code:

# dpkg -S `which ip`
iproute: /sbin/ip

Use "apt-get install iproute" or "yum install iproute" command for Debian/Ubuntu and Centos/RHEL/Fedora (assuming correct repositories are enabled).

Code:

# ip ro get help
Usage: ip route { list | flush } SELECTOR
       ip route get ADDRESS [ from ADDRESS iif STRING ]
                            [ oif STRING ]  [ tos TOS ]
       ip route { add | del | change | append | replace | monitor } ROUTE
SELECTOR := [ root PREFIX ] [ match PREFIX ] [ exact PREFIX ]
            [ table TABLE_ID ] [ proto RTPROTO ]
            [ type TYPE ] [ scope SCOPE ]
ROUTE := NODE_SPEC [ INFO_SPEC ]
NODE_SPEC := [ TYPE ] PREFIX [ tos TOS ]
             [ table TABLE_ID ] [ proto RTPROTO ]
             [ scope SCOPE ] [ metric METRIC ]
             [ mpath MP_ALGO ]
INFO_SPEC := NH OPTIONS FLAGS [ nexthop NH ]...
NH := [ via ADDRESS ] [ dev STRING ] [ weight NUMBER ] NHFLAGS
OPTIONS := FLAGS [ mtu NUMBER ] [ advmss NUMBER ]
           [ rtt NUMBER ] [ rttvar NUMBER ]
           [ window NUMBER] [ cwnd NUMBER ] [ initcwnd NUMBER ]
           [ ssthresh NUMBER ] [ realms REALM ]
TYPE := [ unicast | local | broadcast | multicast | throw |
          unreachable | prohibit | blackhole | nat ]
TABLE_ID := [ local | main | default | all | NUMBER ]
SCOPE := [ host | link | global | NUMBER ]
FLAGS := [ equalize ]
MP_ALGO := { rr | drr | random | wrandom }
NHFLAGS := [ onlink | pervasive ]
RTPROTO := [ kernel | boot | static | NUMBER ]

# ip ro get 10.1.1.1
10.1.1.1 via 172.30.10.1 dev eth0  src 172.30.10.230
    cache  mtu 1500 advmss 1460 hoplimit 64