How do I check if a port is open or closed?

[Guest_imported]

Ok I've taken over for another System Administrator who had done a lot of hardening of the system. Now I have a user who is having a problem connecting to a certain port. I believe its a firewall issue but still I want to check. Its Port 8080 which isn't in the /etc/services file but I don't think it needs to be. I tried using pmadm -l to see if the port was open but I still can't tell. So is there a method to check ports that are open. I snooped port 8080 and there is no traffic but that doesn't tell me if it is the firewall or my port that isn't allowing it. I really don't have much experience with ports so any information will probably be helpful.

 

[cfsalmeida]

you can use netstat, eg:

# netstat -an | grep LISTEN

or check if a process on the machine is running on port 8080,with "pfiles", eg:

# cd /proc
# pfiles * > /tmp/procs

then edit "/tmp/procs" and do a search for "8080".

Hope it helps,

Regards,

Carlos Almeida,

 

[aixmurderer]

Try a telnet to the port, if it's open you should get some sort of a partial login, else it will just sit there "trying...":

telnet <ipaddress> <portnumber> IBM Certified Specialist - MQSeries
IBM Certified Specialist - AIX 5 pSeries System Administration

 

[Guest_imported]

Thanks for all the help. I figured out it was running on the machine and it was opened on the firewall but only for the virtual ip of my machine. Thanks again.