IPV6 required for X11 Forwarding with SSH? Can this be fixed?

English Network/Internet
1

I ran into this years ago, and completely forgot the “solution”. I use `ssh -X root@localhost’ so that I can run X apps from a root authenticated xterm. I’ve been doing so for years. I just did a new install of openSuse 13.1 and got the error message:

X11 forwarding request failed on channel 0

when I sshed to root.

It makes perfect sense to disable IPV6 on a network where it is not used. Unfortunately, the only way I know to get `ssh -X’ to work is to enable IPV6. Is there a way to make ssh to work without enabling the unnecessary IPV6?

This issue cost me a lot of time, again.

2

Have you tried:


ssh -4 -X localhost

or have you tried adding a line


AddressFamily inet

to either your own “.ssh/config” or to “/etc/ssh/ssh_config”?

I don’t disable IPv6 here, so I have not run into your problem. It seems mostly harmless to leave IPv6 enabled, even when your ISP does not support it.

3

I am able to do “ssh -X root@localhost” even with IPv6 disabled. But I get a lot of interesting error messages, when I start applications in this root ssh session.
Why don’t you use a simple “su” to become root in a terminal?

Hendrik

4

Yes, the Golden Rule is in any case not to log in as root, particularly not over the network. So first ssh as a normal user, then do

su -

and not the simple su as suggested.

5

On 06/29/2014 03:36 PM, hcvv pecked at the keyboard and wrote:
> hendwolt;2651362 Wrote:
>> I am able to do “ssh -X root@localhost” even with IPv6 disabled. But I
>> get a lot of interesting error messages, when I start applications in
>> this root ssh session.
>> Why don’t you use a simple “su” to become root in a terminal?
>>
>> Hendrik
> Yes, the Golden Rule is in any case not to log in as root, particularly
> not over the network. So first ssh as a normal user, then do
>
> Code:
> --------------------
> su -
> --------------------
>
> and not the simple su as suggested.
>
>

I have better luck using kdesu after a login to the remote machine using
my login.

Ken

6

That is of course the same principle (and there are similar solutions when one uses Gnome, …).

But he logs in using SSH and that is a CLI session. You do remote login to a GUI session.

7

You can run “kdesu” (or “gnomesu” or “xdg-su”) in a remote session via SSH (that is a CLI session) as well to start GUI applications as root. I think that’s what kensch meant.

8

On 06/29/2014 04:36 PM, hcvv pecked at the keyboard and wrote:
> kensch;2651378 Wrote:
>>
>> I have better luck using kdesu after a login to the remote machine using
>> my login.
>>
>> Ken
> That is of course the same principle (and there are similar solutions
> when one uses Gnome, …).
>
> But he logs in using SSH and that is a CLI session. You do remote login
> to a GUI session.
>
>

I SSH in using konsole in a KDE GUI session.

Ken

9

On Sat, 28 Jun 2014 22:26:01 +0000, hattons wrote:

> I ran into this years ago, and completely forgot the “solution”. I use
> `ssh -X root@localhost’ so that I can run X apps from a root

authenticated xterm. I’ve been doing so for years. I just did a new
install of openSuse 13.1 and got the error message:

Code:

X11 forwarding request failed on channel 0

when I sshed to root.

It makes perfect sense to disable IPV6 on a network where it is not
used. Unfortunately, the only way I know to get `ssh -X’ to work is to
> enable IPV6. Is there a way to make ssh to work without enabling the
> unnecessary IPV6?
>
> This issue cost me a lot of time, again.

IIRC, you need to change the AddressFamily in /etc/ssh/sshd_config to
“inet” instead of the default of “any”.

Jim

–
Jim Henderson
openSUSE Forums Administrator
Forum Use Terms & Conditions at http://tinyurl.com/openSUSE-T-C

10

On Sat, 28 Jun 2014 22:26:01 GMT, hattons
<hattons@no-mx.forums.opensuse.org> wrote:

>
>I ran into this years ago, and completely forgot the “solution”. I use
>`ssh -X root@localhost’ so that I can run X apps from a root

authenticated xterm. I’ve been doing so for years. I just did a new
install of openSuse 13.1 and got the error message:

Code:

X11 forwarding request failed on channel 0

when I sshed to root.

It makes perfect sense to disable IPV6 on a network where it is not
used. Unfortunately, the only way I know to get `ssh -X’ to work is to
>enable IPV6. Is there a way to make ssh to work without enabling the
>unnecessary IPV6?
>
>This issue cost me a lot of time, again.

Very interesting (strange). I have a mix of oS 11.4, 12.1, and 12.3 and
use

ssh -X <target machine>

all the time. If i need to do administrative chores remotely i use

su -

from the Konsole level where i did ssh -X from.

No IPv6 on any of the machines.

I also run

ssh -X

on multiple tabs of Konsole from the same client to the same target
machines almost all the time.

If i want i can use or administer any machine from any machine at any
time.

?-)