I have a Redhat 7.1 dedicated server and have noticed recently that when i have over 100 people connecting to a specific port lets say 1111 then the connection to that port becomes incredibly slow.

telnet 127.0.0.1 1111
Connecting...

then 10 seconds later it displays:

telnet 127.0.0.1 1111
Connecting...
Welcome To Port 1111

*Thats all just an example, but im sure it shouldnt be happening.

What id be interested in knowing is if its a known configuration problem with the OS or if it could be a problem with the program that is on port 1111, Id like to remind you that it ONLY happens when there are approximately 100 or above people connected to the port/server at once.

I have tried rebooting the server and restarting the program, etc...

Any help/troubleshooting would be greatly appreciated. as its very difficult for me to emulate the problem without a live server as it only happens when over 100 people are connected.

Thanx for any help in advance.

-XT

id also like to update aswell, that if you connect on port 1112 or any other port then its instant, same server, just a different port and its then instant.

It would help to know what service your providing on the port and what program is servicing it. It could be a limit of the program, or an I/O limit somewhere.

Typically I'd think that each process would have limits on the number of sockets that it could have open. That's why we like to spawn children when writing a program that requires a lot of open connections.

There is a lot of overhead involved when keeping 100 tcp connections open at once.

Hi,

I presume it is something running via XINETD. In that case you have a limit or other config option set. If you need help go to

/etc/xinet.d/

and find the configuration file for the service concerned and paste it here. We can try and help you out. Would be nice to know exactly what software you are specifically having the problem with.


Cheers


Gareth Robins
NETRG.NET

Could be a DNS problem. I've had similar problems before. When you telnet in, the server will try to do a reverse dns lookup of your ip address. If the dns is slow or timing out it'll slow you down. You might see the same thing happen with ftp as well.