[TriLUG] Choosing the right pipe

Andrew Perrin clists at perrin.socsci.unc.edu
Mon Oct 28 15:50:43 EST 2002


I think it's a function of the routing table; ssh just requests a
connection to a given address, and the underlying IP stack sends the
packets out the appropriate card.

For example, if you've got a local network 192.168.0.x and an external
network of everything else routed through a gateway, your routing table
might look like this:

nujoma:~> /sbin/route 
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
64.130.18.40    *               255.255.255.252 U     0      0        0
eth1
192.168.0.0     *               255.255.255.0   U     0      0        0
eth0
default         dsl-64-130-18-4 0.0.0.0         UG    0      0        0
eth1

That means that to get to the IP address 64.130.18.40 (which is the
gateway router for my home machine) packets should be routed through
eth1; to get to the network 192.168.0.0 packets should be routed through
eth0; and to get anywhere else, they should be sent through the gateway
64.130.18.40, which means they'll use eth1 also.

HTH.

----------------------------------------------------------------------
Andrew J Perrin - http://www.unc.edu/~aperrin
Assistant Professor of Sociology, U of North Carolina, Chapel Hill
clists at perrin.socsci.unc.edu * andrew_perrin (at) unc.edu


On Mon, 28 Oct 2002, Jeff Bollinger wrote:

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> Say I've got two different NICs, each connecting to a different network.
> ~ If I want to SSH into network A (a private network) how do I tell SSH
> to run through eth0 (or the first NIC)?
> 
> Thanks,
> Jeff
> - --
> Jeff Bollinger
> University of North Carolina
> IT Security Analyst
> 105 Abernethy Hall
> mailto: jeff_bollinger at unc dot edu
> 
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