X-server access problem in RH 7.1

X-server access problem in RH 7.1

Post by Andre » Thu, 07 Jun 2001 05:30:08



Hi all,
   We have recently installed Red Hat 7.1 on on of our servers. We are
looking to access it remotely. We have a seperate DHCP server which is
working fine. We have Gnome installed, and everything works just great on
the local machine. Unfortunately, when we try to access the machine
remotely (from another machine on the same LAN), we cannot connect. We
have no problem pinging the 7.1 box, but when we try and access it with
telnet or a remote X-server... we cannot access it. Telnet is installed so
it should work from the local machine. There only error messages we
getare "connection failed". We think it might be a problem with available
UDP ports on the machine. How do we check this, and how do we change the
settings? If anyone has encountered similar problems, their advice would
be very appreciated.

Thanks in advance,
Andrew

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X-server access problem in RH 7.1

Post by nord » Thu, 07 Jun 2001 06:03:46



> Telnet is installed so it should work from the local machine. There only
> error messages we get are "connection failed".

Is telnet installed or telnetd? In order to start a connection, you must
have telnetd installed _and_ it has to be running (see /etc/xinetd.conf on
RH systems). What about connecting via telnet from the Linux box to itself?

Quote:>We think it might be a problem with available UDP ports on the machine.

Surely not. Telnet doesn't use UDP, and your machine cannot run out of
ports (assuming you are not running >60,000 apps at once)

Do you have a firewall set up that might mess up things?

nordi

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Visit http://private.addcom.de/nordi

 
 
 

X-server access problem in RH 7.1

Post by Andre » Thu, 07 Jun 2001 09:30:11


 Thank you for your quick response

Quote:> Is telnet installed or telnetd? In order to start a connection, you must
> have telnetd installed _and_ it has to be running (see /etc/xinetd.conf on
> RH systems). What about connecting via telnet from the Linux box to itself?

In our xinetd.conf everything seems to be okay - What are some possible or likely candidates for mistakes in this file? We CAN telnet into the box from itself, this is why I think telnetd is installed and running. How can I check if it is running or not?

Quote:> Do you have a firewall set up that might mess up things?

No, both machines are on the LAN behind the firewall. Is it possible RedHat is setting up its own firewall and not allowing telnet access from a remote computer?

Still Troubled in Toronto,
Andrew

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X-server access problem in RH 7.1

Post by Tony » Thu, 07 Jun 2001 12:43:09


1. Make sure telnetd is running (/etc/xinetd.d/telnet -> disable=no), then
restart xinetd (/sbin/service restart xinetd) or better yet, use ssh. By
default the sshd is on and you need a client capable of ssh 2 connections
(this is the preferred method - telnet is so "yesterday").

2. To get remote X connections, you need to edit 2 files:
        - /etc/X11/xdm/xdm-config -> comment out the last line
        - /etc/X11/xdm/Xaccess -> look for '#*  allow any host to connect'
                remove the # or add ip addresses of machines you
                wish to allow access

[ Tony ]


> Hi all,
>    We have recently installed Red Hat 7.1 on on of our servers. We are
> looking to access it remotely. We have a seperate DHCP server which is
> working fine. We have Gnome installed, and everything works just great on
> the local machine. Unfortunately, when we try to access the machine
> remotely (from another machine on the same LAN), we cannot connect. We
> have no problem pinging the 7.1 box, but when we try and access it with
> telnet or a remote X-server... we cannot access it. Telnet is installed so
> it should work from the local machine. There only error messages we
> getare "connection failed". We think it might be a problem with available
> UDP ports on the machine. How do we check this, and how do we change the
> settings? If anyone has encountered similar problems, their advice would
> be very appreciated.

> Thanks in advance,
> Andrew

> --
> Posted via CNET Help.com
> http://www.help.com/

 
 
 

X-server access problem in RH 7.1

Post by Andre » Thu, 07 Jun 2001 22:30:07


We had already tried these steps, and it still doesn't seem to work. What
could be our problem?

SSH will also not connect. The linux box seems to be accessing the network
just fine - we just can't access the linux box.

Andrew

Quote:> 1. Make sure telnetd is running (/etc/xinetd.d/telnet -> disable=no),
then
> restart xinetd (/sbin/service restart xinetd) or better yet, use ssh. By
> default the sshd is on and you need a client capable of ssh 2
connections
> (this is the preferred method - telnet is so "yesterday").

> 2. To get remote X connections, you need to edit 2 files:
>         - /etc/X11/xdm/xdm-config -> comment out the last line
>         - /etc/X11/xdm/Xaccess -> look for '#*  allow any host to
connect'
>                 remove the # or add ip addresses of machines you
>                 wish to allow access

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X-server access problem in RH 7.1

Post by Joshua Baker-LePai » Thu, 07 Jun 2001 23:29:05



> No, both machines are on the LAN behind the firewall. Is it possible
> RedHat is setting up its own firewall and not allowing telnet access
> from a remote computer?

Yes.  In fact, it's likely.  Check 'chkconfig --list'.  Is ipchains on?
Then, look in /etc/sysconfig/ipchains.  Those are the firewall rules
being applied.  I'm not sure how you installed RedHat, but when I've
done it the default firewall rules deny access on all priviledged ports.
You need to allow access to the appropriate ports from your clients.

--
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University

 
 
 

X-server access problem in RH 7.1

Post by Markku Kolkk » Fri, 08 Jun 2001 00:20:10



> No, both machines are on the LAN behind the firewall. Is it possible RedHat is setting up its own firewall and not allowing telnet access from a remote computer?

Yes, there's a firewall setup step in the RH7.1 installation, and if I
remember correctly the default setting is "maximum security" which
doesn't allow any incoming connections. Use lokkit or gnome-lokkit to
change the firewall configuration.

--
        Markku Kolkka

 
 
 

X-server access problem in RH 7.1

Post by Andre » Fri, 08 Jun 2001 06:30:04


Problem solved!

 As Markku wrote, there was a default firewall set-up. I used the
command "lokkit", set the configuration to "no firewall" (this machine is
already behind a firewall - so only the local LAN can access it anyways).
I then found that I had to logout of the machine, log back in, and restart
x. Thanks a lot to all who wrote telling me of the many steps to a
solution.

Andrew



> > No, both machines are on the LAN behind the firewall. Is it possible

RedHat is setting up its own firewall and not allowing telnet access from
a remote computer?

> Yes, there's a firewall setup step in the RH7.1 installation, and if I
> remember correctly the default setting is "maximum security" which
> doesn't allow any incoming connections. Use lokkit or gnome-lokkit to
> change the firewall configuration.

> --
> Markku Kolkka


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X-server access problem in RH 7.1

Post by nord » Sat, 09 Jun 2001 22:51:55



> In our xinetd.conf everything seems to be okay - What are some possible or
> likely candidates for mistakes in this file? We CAN telnet into the box
> from itself, this is why I think telnetd is installed and running. How can
> I check if it is running or not?

If you can telnet into your box with "telnet localhost" then telnetd is
running. You can always check with "ps ax | grep telnetd" which will show
the command itself and the telnetd if its running.
With telnet you have to login as a normal user, not root, maybe that's the
problem?

Quote:> No, both machines are on the LAN behind the firewall. Is it possible
> RedHat is setting up its own firewall and not allowing telnet access from
> a remote computer?

I don't think RH sets up a firewall by default. Maybe you have played
around with the /etc/hosts.* files and messed something up. Does the
"connection failed" message appear when using the remote X-server or telnet?

Why don't you simply try ssh, maybe that works.

nordi

--
Linux - Less bugs for less bucks!

Visit http://private.addcom.de/nordi

 
 
 

X-server access problem in RH 7.1

Post by jeff » Sun, 10 Jun 2001 13:01:13


It is my experience that yes, RH 7.1 does indeed install a firewall by
default, unless during the installation process you select high(default)
medium or none and then choose to also "customize". I select medium and then
the "customize" tab and put a checkmark in ssh. If you want telnet or ftp
you will have to check those as well.  For the ability to export your
$DISPLAY from another host to this machine you will also have to add port
6000 to the other ports option in the customization settings of the firewall
config. Or just select firewall none ... your personal discretion is needed
to make that call.

You can access this rudimentary firewall via an application called lokkit
from the command line or I think that there is a cute button for it in menu
"firewall-config"

You might also check your hosts.allow and hosts.deny files. You may have to
add

ALL:    .yourdomain.com

and since ssh is by default compiled with tcpwrappers support you will need
to add
sshd:     ALL or .yourdomain.com

even if you enabled ssh through the firewall on the local machine.

HTH
cheers



> > In our xinetd.conf everything seems to be okay - What are some possible
or
> > likely candidates for mistakes in this file? We CAN telnet into the box
> > from itself, this is why I think telnetd is installed and running. How
can
> > I check if it is running or not?

> If you can telnet into your box with "telnet localhost" then telnetd is
> running. You can always check with "ps ax | grep telnetd" which will show
> the command itself and the telnetd if its running.
> With telnet you have to login as a normal user, not root, maybe that's the
> problem?

> > No, both machines are on the LAN behind the firewall. Is it possible
> > RedHat is setting up its own firewall and not allowing telnet access
from
> > a remote computer?

> I don't think RH sets up a firewall by default. Maybe you have played
> around with the /etc/hosts.* files and messed something up. Does the
> "connection failed" message appear when using the remote X-server or
telnet?

> Why don't you simply try ssh, maybe that works.

> nordi

> --
> Linux - Less bugs for less bucks!

> Visit http://private.addcom.de/nordi

 
 
 

1. Move users from RH 6.1 server to RH 7.1 server

To All,

I am looking for a specific utility/script or reference how-to or FAQ or
other documented procedure to move (actually copy I guess) existing users
from one Redhat 6.1 server to an existing Redhat 7.1 server.  Searching
various newsgroups, I have read a number of speculations as to how to do
this but no one seems to want to commit to anything.  I find it hard to
believe that this is the first time anyone has had to do this and I am very
surprised there isn't an existing how-to on this.

Based on the research I have done so far, the following issues seem to be
relevant although I'm not certain to what extent.

1.  I would like this to be seamless for the users - so no password changes.
2.  All user data and mail data needs to be moved - the old server will be
going off-line at the conclusion of the move
3.  There are some existing users on the new server so there would probably
be some userid/groupid conflicts
4.  I have read that you can just copy relevant portions of the passwd file
but then I read some possible issues related to PAM differences between the
operating systems that might make that difficult plus there is the
userid/groupid conflicts.
5.  We are using shadow passwords
6.  We are not using NIS

Any help would really be appreciated.  Thanks.

-Jeremy

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