What is the callbook service
 

I just ran nmap on a Fedora system and the only interesting item was:

PORT STATE SERVICE
2000/tcp open callbook

I have been looking everywhere and I only see reference to this "callbook" in other postings of open ports. However I am trying to find out exactly what this service is.

Any pointers in the right direction would be appreciated.

---
TIA
Blaine

$ cat /etc/services | grep 2000
# The following is probably Kerberos v5 --- ajt@debian.org (11/02/2000)
sieve 2000/tcp # Sieve mail filter daemon

So according to /etc/services it's sieve mail filter daemon.

The odd thing is though (which I should have mentioned in my post, sorry) is that there is no reference to port 2000 in /etc/services. The line:

cat /etc/services | grep 2000

displays nothing.

ps -aux show every running process
netstat -nat shows all open ports
nmap -sV checks service & app names/versions
and chkrootkit checks for rootkits on your system.

Thanks for the help, I have found it to be Asterisk. nMap says it is unknown what it is. I turned off the asterisk service though and ran nmap again and port 2000 was not showing up. So now I know what is going on.

BTW Is there a command that will tell you which process is using which port?

--
Thanks
Blaine

Solution to last question.
 

I know this is WAY late, but since this post shows up fairly high in google listings i'm going to answer it anyway.

As root, run the command
netstat -lp

On linux systems and most other flavors of *nix this will show you all listening ports along with the name and process ID of every listing service.

Thanks but please do not resurrect stale threads.

Given a Proccess Id try 'lsof -Pwnp [PID] -ai'.
Without Process Id try 'lsof -Pwnai' or 'netstat -antupe'.
Given a port number try '/sbin/fuser -n [PROTOCOL] [PORT_NUMBER]'.
Given a service name (/etc/services) try '/sbin/fuser -n [PROTOCOL] [SERVICE_NAME]'.
* Note you can keep tools from resolving address, service and port names to speed up execution often using switches like "-n".
** Also see 'iptstate -fs -D [REMOTE_IP]', 'awk '/dport=[PORT_NUMBER]/ {print}' /proc/net/ip_conntrack;'.