xdm/kdm port 1024 usage

xdm/kdm port 1024 usage

Post by Kenneth Porte » Fri, 17 Dec 1999 04:00:00



It looks like xdm from XFree86 uses port 1024, or whatever unrestricted
port is the first available when xdm starts. This socket is then
inherited by all children of xdm, ie. shells and user programs. What is
xdm using this port for? I expect I need to firewall that port on my
external interface, as I do now with port 6000.

Is there any information anywhere on what ports are used by X, apart
from the source code?

 
 
 

xdm/kdm port 1024 usage

Post by J. S. Jense » Sat, 18 Dec 1999 04:00:00



> What is xdm using this port for?

xdm will use this for any other x server wishing to use it's display
managment.

Quote:> I expect I need to firewall that port ...

Depends on if you connect to your xdm from any other x server (terminal).

--
J. S. Jensen

http://www.saba.com

 
 
 

xdm/kdm port 1024 usage

Post by Eric L. Schot » Thu, 23 Dec 1999 04:00:00



> It looks like xdm from XFree86 uses port 1024, or whatever unrestricted
> port is the first available when xdm starts. This socket is then
> inherited by all children of xdm, ie. shells and user programs. What is
> xdm using this port for? I expect I need to firewall that port on my
> external interface, as I do now with port 6000.

Insert the line

    DisplayManager.requestPort:     0

to /etc/X11/xdm/xdm-config

+--------------------------------------------------------------------------+

|   The Pennsylvania State University     live her. When all the suns and  |
|   Office: (814) 863-4194                nebulae have passed away, each   |
|   Fax:    (814) 863-7841                one of you will still be alive.  |
|   http://www.personal.psu.edu/els6             C. S. Lewis, 1949         |
+--------------------------------------------------------------------------+

 
 
 

xdm/kdm port 1024 usage

Post by Kenneth Porte » Fri, 24 Dec 1999 04:00:00




> > It looks like xdm from XFree86 uses port 1024, or whatever unrestricted
> > port is the first available when xdm starts. This socket is then
> > inherited by all children of xdm, ie. shells and user programs. What is
> > xdm using this port for? I expect I need to firewall that port on my
> > external interface, as I do now with port 6000.

> Insert the line

>     DisplayManager.requestPort:     0

> to /etc/X11/xdm/xdm-config

What does that do? I looked at "man xdm" and it says that requestPort is
the port to listen on for incoming XDMCP messages, and defaults to 177.
Why would setting it to 0 make xdm stop listening on port 1024?

[This message was both posted and emailed.]

 
 
 

xdm/kdm port 1024 usage

Post by Kenneth Porte » Fri, 31 Dec 1999 04:00:00


Thanks for the explanation. Do I need port 177 only for XDMCP-capable
servers? I'm using the freeware MI/X on an internal Windows box for most
of my access, and this server doesn't talk XDMCP.

Also, I just upgraded to RH6.1, which replaced xdm with gdm. Can gdm be
configured to manage a non-XDMCP external X server? With xdm, I added a
"foreign" entry for my Windows box in the xdm-config file. What would be
the equivalent in gdm, if any?





> >> > It looks like xdm from XFree86 uses port 1024, or whatever unrestricted
> >> > port is the first available when xdm starts. This socket is then
> >> > inherited by all children of xdm, ie. shells and user programs. What is
> >> > xdm using this port for? I expect I need to firewall that port on my
> >> > external interface, as I do now with port 6000.

> >> Insert the line

> >>     DisplayManager.requestPort:     0

> >> to /etc/X11/xdm/xdm-config

> >What does that do? I looked at "man xdm" and it says that requestPort is
> >the port to listen on for incoming XDMCP messages, and defaults to 177.
> >Why would setting it to 0 make xdm stop listening on port 1024?

> True, the requestPort resource defaults to 177, and sets the UDP port
> which xdm listens on for requests. Setting requestPort to zero disables
> this UDP port. But it also disables xdm's TCP port, which typically is
> on port 1024.  Doing this, you lose the ability to have remote X server
> displays connect to your xdm, but will not affect controlling the local
> X server.

> Back to the original question. TCP port 1024 (actually, the first
> unreserved port available when xdm starts) is used by xdm to talk
> to chooser. Xdm starts chooser, then waits for chooser to tell it
> what host you picked. Chooser talks back to xdm through that port.

 
 
 

1. kdm and port 1024

I've noticed (as have many other people) in the last couple weeks
that I have port 1024 TCP listed as listening in netstat.  I'm
told this port is watched by kdm.  Anyone know why?  According to

for it.  Until I know precisely what this port is used for, I've
blocked it in every direction using ipchains...

Thanks -
Jon

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