How to see on Linux what network interface and source IP address is used for a route to a specific destination host?

Question

If I have multiple network interfaces (here: 2) on a Linux machine (here: Debian Lenny). How do I see, over what network interface (NIC) a route to a specific destination host is going and what source IP address is used by default?

I have though of using

ping -I nic1 desthost.example.com
ping -I nic2 desthost.example.com

too see if both ways are possible. (Here: Both ways are possible)

I looked up the routing table

ip route show

But it's quite complex, so I thought, there must by a small simple tool, to just tell me:

"To destination host desthost.example.com it takes interface nicX and source IP address 10.0.0.1"

What is the simplest way of getting this information?

(And I'd rather not use tcpdump and set the interfaces in promiscous mode.)

Thanks.

Solution

Use ip route get <ip>.

Comments

[mivk]

And to get only the interface: ip -o route get $ipaddress | perl -nle 'if(/dev\s+(\S+)/) {print $1}'

[ShadowFlame]

or ip -o route get $ipaddress | awk '{ print $5 }'

[madCode]

route is deprecated. use iproute2.

[Per Lundberg]

What is nm-tool and in what package is it provided? Something related to NetworkManager?

[Nasir]

ip -6 route get 240b:c020:104:5422:bb27:2:1d:134 for example doest print anything. But its pingable

[Admin]

Recent Linuxes dropped netstat in favor of ss.

[Admin]

Yes, it required NetworkManager (which is not installed universally).

[Admin]

Please make the answer somewhat more complete (e.g. explain). If I try the command I just get a header.