ssh X forward broken
Pete Carah
pete at altadena.net
Fri May 21 11:34:51 PDT 2004
Using a -current (a week or two old cvsup) ssh client against several
versions of server (some the same, some the version in 4.9) I'm getting
improper behavior of X forwarding; the emulated server has almost no
extensions and many calls fail.
ssh -v on client side:
port2# ssh -v
OpenSSH_3.8.1p1 FreeBSD-20040419, OpenSSL 0.9.7d 17 Mar 2004
...
sshd -v on server side:
OpenSSH_3.8.1p1 FreeBSD-20040419, OpenSSL 0.9.7d 17 Mar 2004
...
One example is that xclock reports the RENDER extension missing (but
then appears to work fine). And scilab won't work at all remotely.
Is the ssh client side screening X calls now?
This is all with fairly current versions of X present (all 4.3.0)
on both sides. xclock doesn't complain if it comes from a much older
X but that is probably because it doesn't try the extension.
xdpyinfo on X server (ssh client) side:
---------------------------------------
port2.altadena% xdpyinfo
name of display: :0.0
version number: 11.0
vendor string: The XFree86 Project, Inc
vendor release number: 40300000
XFree86 version: 4.3.0
maximum request size: 4194300 bytes
motion buffer size: 256
bitmap unit, bit order, padding: 32, LSBFirst, 32
image byte order: LSBFirst
number of supported pixmap formats: 7
supported pixmap formats:
depth 1, bits_per_pixel 1, scanline_pad 32
depth 4, bits_per_pixel 8, scanline_pad 32
depth 8, bits_per_pixel 8, scanline_pad 32
depth 15, bits_per_pixel 16, scanline_pad 32
depth 16, bits_per_pixel 16, scanline_pad 32
depth 24, bits_per_pixel 32, scanline_pad 32
depth 32, bits_per_pixel 32, scanline_pad 32
keycode range: minimum 8, maximum 255
focus: window 0x3e00005, revert to PointerRoot
number of extensions: 30
BIG-REQUESTS
DEC-XTRAP
DOUBLE-BUFFER
DPMS
Extended-Visual-Information
FontCache
GLX
LBX
MIT-SCREEN-SAVER
MIT-SHM
MIT-SUNDRY-NONSTANDARD
RANDR
RECORD
RENDER
SECURITY
SGI-GLX
SHAPE
SYNC
TOG-CUP
X-Resource
XC-APPGROUP
XC-MISC
XFree86-Bigfont
XFree86-DGA
XFree86-Misc
XFree86-VidModeExtension
XInputExtension
XKEYBOARD
XTEST
XVideo
default screen number: 0
number of screens: 1
screen #0:
dimensions: 1024x768 pixels (347x260 millimeters)
resolution: 75x75 dots per inch
depths (7): 24, 1, 4, 8, 15, 16, 32
root window id: 0x3b
depth of root window: 24 planes
number of colormaps: minimum 1, maximum 1
default colormap: 0x20
default number of colormap cells: 256
preallocated pixels: black 0, white 16777215
options: backing-store NO, save-unders NO
largest cursor: 64x64
current input event mask: 0xda4031
KeyPressMask EnterWindowMask LeaveWindowMask
KeymapStateMask StructureNotifyMask SubstructureNotifyMask
SubstructureRedirectMask PropertyChangeMask ColormapChangeMask
number of visuals: 4
default visual id: 0x22
visual:
visual id: 0x22
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0x23
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0x24
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0x25
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
------------------------------------------------------------
xdpyinfo as seen when run on ssh server side:
---------------------------------------------
users.altadena% xdpyinfo
name of display: localhost:12.0
version number: 11.0
vendor string: The XFree86 Project, Inc
vendor release number: 40300000
XFree86 version: 4.3.0
maximum request size: 4194300 bytes
motion buffer size: 256
bitmap unit, bit order, padding: 32, LSBFirst, 32
image byte order: LSBFirst
number of supported pixmap formats: 7
supported pixmap formats:
depth 1, bits_per_pixel 1, scanline_pad 32
depth 4, bits_per_pixel 8, scanline_pad 32
depth 8, bits_per_pixel 8, scanline_pad 32
depth 15, bits_per_pixel 16, scanline_pad 32
depth 16, bits_per_pixel 16, scanline_pad 32
depth 24, bits_per_pixel 32, scanline_pad 32
depth 32, bits_per_pixel 32, scanline_pad 32
keycode range: minimum 8, maximum 255
focus: window 0x460000c, revert to PointerRoot
number of extensions: 3
BIG-REQUESTS
LBX
XC-MISC
default screen number: 0
number of screens: 1
screen #0:
dimensions: 1024x768 pixels (347x260 millimeters)
resolution: 75x75 dots per inch
depths (7): 24, 1, 4, 8, 15, 16, 32
root window id: 0x3b
depth of root window: 24 planes
number of colormaps: minimum 1, maximum 1
default colormap: 0x20
default number of colormap cells: 256
preallocated pixels: black 0, white 16777215
options: backing-store NO, save-unders NO
largest cursor: 64x64
current input event mask: 0xda4031
KeyPressMask EnterWindowMask LeaveWindowMask
KeymapStateMask StructureNotifyMask SubstructureNotifyMask
SubstructureRedirectMask PropertyChangeMask ColormapChangeMask
number of visuals: 4
default visual id: 0x22
visual:
visual id: 0x22
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0x23
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0x24
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0x25
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
--------------------------------------------------------
Another thing I see is that the xauth data on the emulated (sshd) side
appears to expire pretty fast - if I run most any program (like sending
this mail) then try an X connection (:r !xdpyinfo in this edit session),
I get:
--------------------------
Xlib: connection to "localhost:10.0" refused by server
Xlib: Invalid MIT-MAGIC-COOKIE-1 key
xdpyinfo: unable to open display "localhost:10.0".
------------------
The X server (ssh client) side of this is using both MIT and XDM
auth. Other side is only MIT...
- Pete
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