Dan Szilagyi wrote:
> New RedHat 5 installation at a university with Internet access via the
> campus ethernet wiring. No firewall. RH5 box can SEE OUT to the Internet,
> but nobody on the Internet can SEE IN to the RH5 box (ping, telnet).
Can the Linux Box establish a connection to an off-subnet node?
Are you pinging the Linux box by name or by address?
Does your system use NIS for any name resolution? If so, does 'ypwhich'
indicate you are bound to a server or slave machine. Can you find your
machine in hosts -- use: 'ypcat hosts | grep <my machine name>'?
[snip]
> Default Gateway looks correct:
> The X Window "Network Configurator" "Routing" option has the "default
> gateway" listed as "138.23.43.1", which is the correct address of the
> router on this particular subnet. "default gateway device" is "eth0".
Do a 'netstat -rn' and let us know what happens. Since you can get out
it is unlikly your default route is set incorrectly but netstat
sometimes give a clue as to what a problem is.
[snip]
> DNS servers are working:
> Performing the "nslookup" command from the Linux box found the campus DNS
> server correctly. (The DNS server is on a different subnet).
Does 'nslookup' find the Linux box? If not, your DNS server may not
know the name.
> (1) Any idea why the machine cannot be seen outside of the local subnet?
> Did I miss something during the configuration?
If the machine can be accessed by address from another machine on the
same subnet but cannot be seen from outside of the subnet, a router may
be at fault. I had a similar problem once because a router was
configured to keep addresses in its ARP cache for some ridiculous length
of time. Check with your network admin and find out how long an address
is kept before being flushed.
> (2) The X Window "Network Configurator" utility's "Routing" option has a
> selection titled "Network Packet Forwarding (IPv4)". What does that do?
> Is it used only if the RH5 machine is used as a router? Or, could it be
> the reason the machine cannot be seen from the Internet?
AFAIK, Packet Forwarding is not necessary to connect to an internet.
(Sorry for all the questions but I work on this kind of problems at
least ten times a week so my armory is kinda full :-)
--
Stephen Carville
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