RE: Get process that bind a port

[Styma, Robert E (Robert)]

>  
>  Hello,
>  I am playing around with writing a program to bind to socket 
>  / port in my 
>  machine. Often time, I got the message:
>  bind(): Address already in use
>  
>  So my question is, how do I find out which process bind to a 
>  certain port 
>  number ? For example, how do I find out what process use port 
>  2345? Sometimes 
>  'ps ax' does not really show the process that I though bind 
>  that port number, 
>  although bind() gave the error message. Plus 'ps ax' does not 
>  really help 
>  unless you know the process name anyway.
>  
>  Thanks for any help.
>  RDB
>   
The command lsof run as root will tell you a lot of things including
who is bound to a port.
For example:
lsof | grep 2345

Note that on various flavors unix, I have seen the "already in use" message
for a short time after a program exits.  That is, start a program which listens
on a certain port, exit the program, immediately restart the program.  A quick test
says FC4 does not seem to do this.

--
Bob Styma

Get process that bind a port

[Gaston Martres]

Maybe it's more easy to use "netstat -tunap".
The -p flag will tell you wich program is running at that port.

Cheers.

--------------------------
Gaston Martres
Tech IT - Soluciones IT
Cel: 15-5614-3012
http://www.tech-it.com.ar
-------------------------- 



STYMA, ROBERT E (ROBERT) wrote:

> >Hello,
> >I am playing around with writing a program to bind to socket 
> >/ port in my 
> >machine. Often time, I got the message:
> >bind(): Address already in use
> >
> >So my question is, how do I find out which process bind to a 
> >certain port 
> >number ? For example, how do I find out what process use port 
> >2345? Sometimes 
> >'ps ax' does not really show the process that I though bind 
> >that port number, 
> >although bind() gave the error message. Plus 'ps ax' does not 
> >really help 
> >unless you know the process name anyway.
> >
> >Thanks for any help.
> >RDB
> >
> >    
> >
> The command lsof run as root will tell you a lot of things including
> who is bound to a port.
> For example:
> lsof | grep 2345
>
> Note that on various flavors unix, I have seen the "already in use" message
> for a short time after a program exits.  That is, start a program which listens
> on a certain port, exit the program, immediately restart the program.  A quick test
> says FC4 does not seem to do this.
>
> --
> Bob Styma 
>
>   
>

Get process that bind a port

[Reuben D. Budiardja]

On Wednesday 30 November 2005 12:54, STYMA, ROBERT E (ROBERT) wrote:
>  > Hello,
>  > I am playing around with writing a program to bind to socket
>  > / port in my
>  > machine. Often time, I got the message:
>  > bind(): Address already in use
>  >
>  > So my question is, how do I find out which process bind to a
>  > certain port
>  > number ?  
>  The command lsof run as root will tell you a lot of things including
>  who is bound to a port.
>  For example:
>  lsof | grep 2345 
Great. Thanks.

>  Note that on various flavors unix, I have seen the "already in
> use" message
>  for a short time after a program exits.  That is, start a program which
>  listens on a certain port, exit the program, immediately restart the
>  program.  A quick test says FC4 does not seem to do this. 
The reason I am asking is because I am seeing exactly this on FC 4. It seems 
that after exiting, the program does not release the port immediately, and 
hence restarting the program get the "already in use" message, while 'ps aux

| grep progname' shows nothing. Maybe I am doing something wrong, ie. the 
program does not release the port cleanly on exit or something like that ? 
I'm not sure...

Thanks a lot for the answer though .
RDB

Get process that bind a port

[Ezra Nugroho]

On Wed, 2005-11-30 at 13:34 -0500, Reuben D. Budiardja wrote:
>  On Wednesday 30 November 2005 12:54, STYMA, ROBERT E (ROBERT) wrote:
>  > > Hello,
>  > > I am playing around with writing a program to bind to socket
>  > > / port in my
>  > > machine. Often time, I got the message:
>  > > bind(): Address already in use
>  > >
>  > > So my question is, how do I find out which process bind to a
>  > > certain port
>  > > number ? 
>  
>  > The command lsof run as root will tell you a lot of things including
>  > who is bound to a port.
>  > For example:
>  > lsof | grep 2345
>  
>  Great. Thanks.
>  
>  > Note that on various flavors unix, I have seen the "already in use"
> message
>  > for a short time after a program exits.  That is, start a program which
>  > listens on a certain port, exit the program, immediately restart the
>  > program.  A quick test says FC4 does not seem to do this.
>  
>  The reason I am asking is because I am seeing exactly this on FC 4. It seems 
>  that after exiting, the program does not release the port immediately, and 
>  hence restarting the program get the "already in use" message, while 'ps
> aux 
>  | grep progname' shows nothing. Maybe I am doing something wrong, ie. the 
>  program does not release the port cleanly on exit or something like that ? 
>  I'm not sure...
>   
Is this an RPC client-server program?
If it is, it's done intentionally so that any messages that may still
float around have a destination to rest in peace.

Use "select()" socket utility.
It may mean a little extra programming, but it is really rewarding.

Get process that bind a port

[Reuben D. Budiardja]

On Wednesday 30 November 2005 14:14, Ezra Nugroho wrote:
>  On Wed, 2005-11-30 at 13:34 -0500, Reuben D. Budiardja wrote:
>  > On Wednesday 30 November 2005 12:54, STYMA, ROBERT E (ROBERT) wrote:
>  > > > Hello,
>  > > > I am playing around with writing a program to bind to socket
>  > > > / port in my
>  > > > machine. Often time, I got the message:
>  > > > bind(): Address already in use
>  > > > 
<snip>
>  > > Note that on various flavors unix, I have seen the
> "already in use"
>  > > message for a short time after a program exits.  That is, start a
>  > > program which listens on a certain port, exit the program, immediately
>  > > restart the program.  A quick test says FC4 does not seem to do this.
>  >
>  > The reason I am asking is because I am seeing exactly this on FC 4.<snip>
>  > | grep progname' shows nothing. Maybe I am doing something
> wrong, ie. the
>  >
>  > program does not release the port cleanly on exit or something like that
>  > ? I'm not sure...
>
>  Is this an RPC client-server program?
>  If it is, it's done intentionally so that any messages that may still
>  float around have a destination to rest in peace. 
No RPC (if I understand what that means correctly), just 'regular' socket 
programming.

>  Use "select()" socket utility.
>  It may mean a little extra programming, but it is really rewarding. 
Not sure how select() would help here. In this case the "server" side just do 
really simple stuff, basically read and write to socket descriptor. It could 
be that when server is interupted, there is still I/O that makes it not 
immediately release the port. Are you saying using select() to clean up ?

RDB

Get process that bind a port

[Ezra Nugroho]

<snip>

>  > Is this an RPC client-server program?
>  > If it is, it's done intentionally so that any messages that may still
>  > float around have a destination to rest in peace.
>  
>  No RPC (if I understand what that means correctly), just 'regular' socket 
>  programming.
>  
>  > Use "select()" socket utility.
>  > It may mean a little extra programming, but it is really rewarding.
>  
>  Not sure how select() would help here. In this case the "server" side just do 
>  really simple stuff, basically read and write to socket descriptor. It could 
>  be that when server is interupted, there is still I/O that makes it not 
>  immediately release the port. Are you saying using select() to clean up ? 

You are right, you don't need select() if you just want to clean up. You
might want to consider it since it gracefully manages resources when
there is some network error/interrupt. Look at the chat server example: 
http://beej.us/guide/bgnet/output/html/advanced.html#select


This is how you clean up the socket.

// lose the pesky "address already in use" error message
if (setsockopt(listener, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) ==
-1) 
{
        perror("setsockopt");
        exit(1);
}

Get process that bind a port

[Reuben D. Budiardja]

On Wednesday 30 November 2005 20:36, Ezra Nugroho wrote:
>  <snip>
>
>
>  You are right, you don't need select() if you just want to clean up. You
>  might want to consider it since it gracefully manages resources when
>  there is some network error/interrupt. Look at the chat server example:
>  http://beej.us/guide/bgnet/output/html/advanced.html#select 
Nice page. Thanks for the pointer.

RDB