[CentOS] Cannot open port 631 for Cups printer sharing

b.j. mcclure keepertoad at bellsouth.net
Mon Mar 2 21:00:48 UTC 2009


On Mon, 2009-03-02 at 15:31 -0500, JohnS wrote:
> On Mon, 2009-03-02 at 15:13 -0500, b.j. mcclure wrote:
> > On Mon, 2009-03-02 at 11:14 -0800, Scott Silva wrote:
> > > on 3-2-2009 8:20 AM b.j. mcclure spake the following:
> > > > I have been trying to set up printer sharing on the LAN.All machines are
> > > > CentOS 5.2 fully updated. The problem server is a fresh build.  The box
> > > > it is replacing worked fine for many months.
> > > > The problem appears to be a closed port 631 on the new box.  iptables
> > > > and ip6tables are stopped as shown by the output below.  To confirm I
> > > > was using nmap correctly I ran it against the old server first which
> > > > shows 631 open.  No matter what I do to the new box (192.168.2.205) 631
> > > > remains closed.  I was running it on the new box via ssh which I think
> > > > eleminates any swithc/router issues.
> > > > 
> > > > Any thoughts gladly accepted.  This must be something simple/stupid I
> > > > have overlooked.  Not much hair left to pull out. ;-/
> > > > 
> > > 
> > > 
> > > Cups defaults to only being open on localhost. You have to edit the config
> > > file to open more up.
> > 
> > Perhaps I misunderstand your suggestion but cupsd.conf is identical for
> > the machine that works properly and the one upon which I cannot get port
> > 631 open, even on localhost.
> > 
> Try this: netstat -n -l -p | grep 631 Maybe a another process has it but
> I think you did say it did not come up with nmap? Last option I know to
> check would be to see if it has a socket file in /var/run/cups. It needs
> that before it will listen on port 631.

Thanks for the suggestions.

[root at webserver ~]# netstat -n -l -p | grep 631
tcp        0      0 ::1:631                     :::*
LISTEN      6941/cupsd          
udp        0      0 0.0.0.0:631                 0.0.0.0:*
6941/cupsd

Looks like cups has it and cups.sock does exist in /var/run/cups.

[root at webserver ~]# ls /var/run/cups
certs  cups.sock

> I've herd many people say the config is the same as the machine but why
> not just take it and try it on the one that want work, then service cups
> restart. Remember something there are no two machines ever alike!

Of course you are right about no two machines being identical.  I did as
requested and copied the working config file to the non working box with
no change.  Port 631 still closed.  I also ran nmap against the
apparently closed port with the -P0 option and it shows "closed" as
distinguished from filtered.

Thanks for the suggestions.
B.J.
CentOS 5.2, Linux 2.6.18-92.1.22.el5 x86_64 15:46:14 up 22:40, 4 users,
load average: 0.09, 0.07, 0.06



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