Re: About network daemons in a multi homed workstation
On Mon, 30 Nov 1998 pedro.i.sanchez@altavista.net wrote:
> Hello,
>
> I have Debian 2.0 in a PC with three different Ethernet interfaces, each
> interface in a different subnet. I notice that network daemons like
> telnet, ftp and NFS only work via the first interface (eth0) and
> completely ignore the other two interfaces.
>
> What has to be done to make them work in all interfaces? Even more, is
> it possible to tell, say NFS, to work on two of them and ignore the
> third one?
>
> Thank you,
>
> Pedro I. Sanchez
>
The network daemons know nothing about such mundane details as to the
network interfaces that a particular system has. They are completely
screened from these details by the IP network layer and the TCP or UDP
transport layers (which is a good thing). If the network interfaces are
configured correctly, then there should be (at least) three IP addresses
assigned to the system, one for each network interface (Ethernet device in
your case). Any of these IP addresses is a valid address for that system.
So, if a user on another system (client) telnets to the system in
question, he would command telnet to connect to one of the IP addresses of
that system (server) and, as long as the client has connectivity with the
server, then the telnet session should occur normally. So without going
into any more details of this, if you're having problems telneting (or
whatever) on two of the three network interfaces, the first thing I'd
check is whether these network interfaces are configured properly. What
does the command 'ifconfig' show? Are the interfaces UP, RUNNING, and are
you receiving and transmitting packets over them? Can you 'ping' other
systems that are on the directly connected networks for those two
interfaces? If the anwsers to all of these are yes then the network
interfaces are probably configured properly and your network services
should work. The other thing that comes to mind is denying host access
through the /etc/hosts.allow, /etc/hosts.deny configuration. See if these
files are configured and read 'man hosts_access' for an explanation.
Hope this helps...
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