Connot connect to port on server : networking problem?

Connot connect to port on server : networking problem?

Post by Amita » Wed, 19 May 2004 18:52:32


We have a unique problem, which I am sure is due to netwroking setup,
whereas our adnministrator are caliming otherwise. We are running
RedHat Linux 3.

I have written a service which listens on a port. Its running on a
server with IP Whenever this listener is
not bound to the hostname, it accepts connections from any machine
whether that request is given with IP or fully qualified server name.

However, whenever we bind the listener to tha particular hostname
( and we try to connect to it from the server itself,
it connaot connect when request is given with IP but connects when
request is given with hostname. BUT, we connot connect to the listner
from any other machine either by using the hostname or IP.

Our requirement is to start the listener bound to hostname (we have no
choice in that) and connect to it from client machine again using

Th e DNS is supposed to be configured  on the server in
sense that we can ping the without a host file

My feeling is that the there is something missing in network/DNS
setup. Can someone guide me what to look at.


PS: Sorry for long post


1. Connecting Linux Box to company network makes network port shut down

Here's a mystery (or perhaps not) for the group:

I attach my Suse 8.2 laptop to the company 10/100 Ethernet network
with a 3Com PCMCIA 575BT card. All is well for about an hour, then the
network port shuts off -- not on the computer side, but on the switch

If I attach the same laptop to another network port on the switch, the
switch's port is shut off (this time within a few minutes) of
commencing simple network activity, like browsing the web. I assume
the switch is working from a cached MAC address acquired before
shutting down the port the first time.

The same behavior occurs on identical hardware running Debian Woody.
No other Linux machines are available to test.

According to my local sysadmin, our office is now running ethernet
switches (sadly, I was unable to obtain the make/model) with a
security feature that automatically shuts off an ethernet port if an
unauthorized switch or hub is attached. She suspects this has
something to do with the problem; as she puts it, "we have the same
problem sometimes with Macs around the office" and "the switch looks
for exceptionally 'chatty' network packets and shuts down the port for
security" and "this happens now if anyone plugs a hub into one of
these switches." This does not occur on any of the office Windows or
Solaris boxen.

She felt that "turning off fast ethernet" on the required ports would
solve the problem, as that solved it for hubs and Macs -- but it
didn't work.

Anyone ever hear of anything like this?


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