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Remote Access Service

Posted on 2014-03-10
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Last Modified: 2014-03-16
Hi.

We have some remote access software running on a Cent OS server. The service is called SimpleHelp if anyone is familiar. We recently migrated from a VPS to a dedicated server and have since been having problems.

The program uses port 900 which has been opened for both TCP and UDP. Clients using a http/tcp connection seem to be working. Those using UDP will show as online but cannot connect (90% use UDP only...).

I used nmap to scan port 900 UDP on the server. It shows as open but the listening service is named: omginitialrefs
This service is not related to our remote access software and I have no idea what it does. Can it safely be stopped and how?

Thanks in advance for any replies
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Question by:KTBerwick
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6 Comments
 

Author Comment

by:KTBerwick
ID: 39918857
Just thought I should add... changing to a different port would be a major difficulty as we would have to manually update every client to look at the new port.

Another thought - If I were to change the remote software to listen on say port 5432 could all traffic destined for port 900 be redirected to port 5432?
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LVL 62

Assisted Solution

by:gheist
gheist earned 500 total points
ID: 39919275
nmap has its own copy of /etc/services
and 900/tcp and 900/udp are registered to OMG for OMG Initial refs protocol
so simplistichelp is free-riding on others horse...
and nmap calls port right

you can check with netstat -anpu that it is fine, nothing to kill (why you poertscan a system when you have netstat?)
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Assisted Solution

by:KTBerwick
KTBerwick earned 0 total points
ID: 39920257
Thanks for the reply.

I have very limited knowledge of Linux so the netstat command never came to mind. I was also trying to verify port 900 was actually open.

Since posting I have made a few changes.
Someone suggested it may be a permissions issue as processes require root privileges to bind any port lower than 1024. I added a firewall redirect for all traffic on port 900 to be forwarded to port 5432. Then I configured the SimpleHelp software to listen on 5432.

This seems to be working. There are maybe 20-30 clients missing but I can deal with adding them again. Far better than the 250+ clients that were missing to begin with.
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LVL 62

Accepted Solution

by:
gheist earned 500 total points
ID: 39920353
netstat is on windows and macintosh too...
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Author Comment

by:KTBerwick
ID: 39922209
I'm aware of netstat I just didn't realise it worked on Linux.

Anyway, the problem is now solved. The missing PC's have came on-line throughout the day and we haven't had any issues since I made the changes described previously.

Adding you as a partial solution as your explanation of the nmap output cleared things up for me.
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Author Closing Comment

by:KTBerwick
ID: 39932364
The firewall redirect of port 900 is what resolved all our problems.
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