Subject: SSH X11 forwarding crashes clients.
To: None <>
From: Lars-Johan Liman <>
List: current-users
Date: 12/01/2005 15:33:17
Anyone else seeing this?

1) Start from 3.99.11 2005-11-28.

2) Start X server and xterm on local machine.

3) ssh with X11 forwarding to remote older box.

4) Start X11 application on remote box (e.g. xterm or emacs).

5) Select text in window opened by remote application.
5a) If emacs, watch client die.

6) Paste text into local window using <SHIFT> + <INSERT>.
6b) If other client (e.g. xterm), watch client die.

The error message I get is:

X protocol error: BadWindow (invalid Window parameter) on protocol request 38

On a Mac (see below) I get the following from xterm:

xterm:  warning, error event received:
X Error of failed request:  BadAtom (invalid Atom parameter)
  Major opcode of failed request:  18 (X_ChangeProperty)
  Atom id in failed request:  0x17e
  Serial number of failed request:  187
  Current serial number in output stream:  189

Now to the strange thing: If I open up direct access to the X server
(xhost +<remote-IP#> - for testing puposes only) and manually set the
DISPLAY to the <IP#> of the local machine (as one did in the old
insecure days ... ;-) on the remote machine _before_ issuing the
commands that start the X11 applications in question, I have no
problems what so ever. Window opens, cut-n-paste works like a charm.

I can repeat this perfectly fine using remote boxes with

NetBSD 1.6ZK, sshd version OpenSSH_3.6.1 NetBSD_Secure_Shell-20030917

MacOS X 10.3.9, sshd version OpenSSH_3.6.1p1+CAN-2004-0175

Linux/Debian unstable, kernel 2.6.12, sshd OpenSSH_4.2p1 Debian-4, OpenSSL 0.9.7g 11 Apr 2005

Since the problem does appear with very different remote hosts, but
doesn't appear with direct X11 connections, I presume the problem sits
in my "local machine" and in its ssh client or some component thereof -
possibly OpenSSL.

BTW, the other way around seems to work fine. Using the X server on
the Mac, logging in (ssh with X11 forw) to my 3.99.11 box, starting
window, etc., seems to be OK.

Comments? "Me-too"s? Known issue? Fix?

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