Open port

[Jamon Camisso]

William O'Higgins Witteman wrote:
> On Thu, Apr 27, 2006 at 10:02:07PM +0300, Peter wrote:
>> On Thu, 27 Apr 2006, William O'Higgins Witteman wrote:
>>
>>> On Wed, Apr 26, 2006 at 08:08:42PM +0300, Peter wrote:
>>>
>>>>> What is the "unknown" process listening on 816?  I notice that this is
>>>>> different port than it had before a reboot, but there was still an open
>>>>> port (I think it had a port around 900-ish).  If I "telnet localhost
>>>>> 816" a session is opened, and I am informed that ^] is the escape key,
>>>>> but that's all it says, and I don't know how to further investigate
>>>>> this.
>>>> root# fuser -vn tcp 816
>>> Thank you, that tells me that the user process is "rpc.statd", which I
>>> assume is supposed to be there and nothing to worry about.  Thanks also
>>> to Vince, who suggested the same thing.
>> Actually you should firewall it imho. Same for all rpc* ports. Do not 
>> connect to the internet with that port open. It belongs to nfs/nfsd and 
>> portmap. So stop and disable that service if not using it.
> 
> The machine is behind a firewall, which is why I wasn't too worried, but
> thank you.  I am not using NFS, so the culprit is portmap.  What does
> portmap do that I need?  Why is it installed by default?

Portmap does exactly that, it maps specified running programs to 
specified (known/registered) ports on your system. In the case of NFS, 
incoming requests for NFS contact the portmap daemon to see where and 
how to contact NFS itself. It is an intermediary that occupies a crucial 
position in regard to NFS. Apart from that, I'm not familiar with any 
other programs that use it, so I can't comment on it outside of its NFS 
role.

Jamon
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