Date: Thu, 10 May 2018 20:29:28 +0200 From: Matthias Apitz <guru@unixarea.de> To: freebsd-x11@freebsd.org Subject: ssh -X remote does not work due to problem with xauth Message-ID: <20180510182928.GA3747@c720-r314251>
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Hello,
I'm facing a problem with running from FreeBSD 'ssh -X remote host'. The
remotre server is a recent SLES Linux system. This thread started in
freebsd-questions@ and I now move it to here as it seems more a problem
of the Xorg server than a ssh problem of the base system.
When I launch 'ssh -X remote host' to get X11 forwarded to my workstation
this does not work, i.e. does not produce a DISPLAY env on the remote
host and says:
$ ssh -X apitzm@srap16dxr1
Warning: untrusted X11 forwarding setup failed: xauth key data not generated
Last login: Wed May 9 12:37:17 2018 from 10.49.8.33
apitzm@srap16dxr1:~>
I digged into it with -vv options for ssh and trussing the client. It seems=
it's
our end causing the problem:
$ uname -a
FreeBSD r314251-amd64 12.0-CURRENT FreeBSD 12.0-CURRENT #0 r314251: Sat Feb=
25 17:14:40 CET 2017
root@r303343-amd64:/usr/obj/usr/src/sys/GENERIC amd64
$ truss -s128 -f -o ssh.tr ssh -X -vv apitzm@srap16dxr1
$ grep xauth ssh.tr
2505: stat("/usr/local/bin/xauth",{ mode=3D-rwxr-xr-x ,inode=3D15268663,si=
ze=3D41056,blksize=3D32768 }) =3D 0 (0x0)
2505: write(2,"debug2: client_x11_get_proto: /usr/local/bin/xauth -f /tmp/=
ssh-adSkh4btDHWr/xauthfile generate :0 MIT-MAGIC-COOKIE-1 untrusted timeout=
1260 2>/dev/null\r\n",153) =3D 153 (0x99)
2506: execve("/usr/local/bin/xauth",0x80145a260,0x80145a408) =3D 0 (0x0)
2506: stat("/tmp/ssh-adSkh4btDHWr/xauthfile-c",0x7fffffffdb80) ERR#2 'No s=
uch file or directory'
2506: openat(AT_FDCWD,"/tmp/ssh-adSkh4btDHWr/xauthfile-c",O_WRONLY|O_CREAT=
|O_EXCL,0600) =3D 3 (0x3)
2506: pathconf("/tmp/ssh-adSkh4btDHWr/xauthfile-c",_PC_LINK_MAX) =3D 32767=
(0x7fff)
2506: link("/tmp/ssh-adSkh4btDHWr/xauthfile-c","/tmp/ssh-adSkh4btDHWr/xaut=
hfile-l") =3D 0 (0x0)
2506: access("/tmp/ssh-adSkh4btDHWr/xauthfile",F_OK) ERR#2 'No such file o=
r directory'
2506: open("/tmp/ssh-adSkh4btDHWr/xauthfile",O_RDONLY,0666) ERR#2 'No such=
file or directory'
2506: access("/tmp/ssh-adSkh4btDHWr/xauthfile",F_OK) ERR#2 'No such file o=
r directory'
2506: write(2,"/usr/local/bin/xauth: file /tmp/ssh-adSkh4btDHWr/xauthfile=
does not exist\n",75) =3D 75 (0x4b)
2506: access("/tmp/kde-guru/xauth-1001-_0",R_OK) =3D 0 (0x0)
2506: open("/tmp/kde-guru/xauth-1001-_0",O_RDONLY,0666) =3D 4 (0x4)
2506: write(2,"/usr/local/bin/xauth: (argv):1: ",33) =3D 33 (0x21)
2506: lstat("/tmp/ssh-adSkh4btDHWr/xauthfile-c",{ mode=3D-rw------- ,inode=
=3D24961,size=3D0,blksize=3D32768 }) =3D 0 (0x0)
2506: unlink("/tmp/ssh-adSkh4btDHWr/xauthfile-c") =3D 0 (0x0)
2506: lstat("/tmp/ssh-adSkh4btDHWr/xauthfile-l",{ mode=3D-rw------- ,inode=
=3D24961,size=3D0,blksize=3D32768 }) =3D 0 (0x0)
2506: unlink("/tmp/ssh-adSkh4btDHWr/xauthfile-l") =3D 0 (0x0)
2505: unlink("/tmp/ssh-adSkh4btDHWr/xauthfile") ERR#2 'No such file or dir=
ectory'
2505: write(2,"Warning: untrusted X11 forwarding setup failed: xauth key d=
ata not generated\r\n",78) =3D 78 (0x4e)
$ grep Sec ssh.tr
2505: read(3,"\0\0\^A\^D\v\^_\0\0\0h\0\0\0\^Secdsa-sha2-nistp256\0\0\0\bni=
stp256\0\0\0A\^D\^Qa<x\^U\M-jW\M-Hy/\M-:\M-b\^Qc\M-\^\^SG\M^ZT|\M-ck7\M-H\M=
-s\M-gKNi\n\M^Ex\M-;D.\M-w\M-'\^O\^T\^Uls\M^Y\M-D\M-5{\M-6\M-3d\M-U\M-P\M-C=
k\M-*7\a\^U\^W\M-^\M^Il\M-n\M-,\0\0\0 M\M-G"...,8192) =3D 364 (0x16c)
2506: write(2,"couldn't query Security extension on display ":0"\n",50) =
=3D 50 (0x32)
One can simulate the xauth call locally and without redirecting STDERR and
will see the same error:
$ /usr/local/bin/xauth -f /tmp/xauthfile generate :0 MIT-MAGIC-COOKIE-1 unt=
rusted timeout 1260
/usr/local/bin/xauth: file /tmp/xauthfile does not exist
/usr/local/bin/xauth: (argv):1: couldn't query Security extension on displ=
ay ":0"
This, and the fact that my colleagues (coming from Ubuntu workstations)
do not face the problem, let me strongly think in a LOCAL problem, maybe
of the Xorg server which is xorg-7.7_2 from the ports.
I straced as well the remote sshd while I ssh'ed into the server. On the re=
mote side there
is no xauth called:
$ grep exec sshd.tr
1369 execve("/usr/sbin/sshd", ["/usr/sbin/sshd", "-D", "-R"], [/* 3 vars *=
/] <unfinished ...>
1369 <... execve resumed> ) =3D 0
1373 execve("/bin/bash", ["-bash"], [/* 12 vars */]) =3D 0
1375 execve("/usr/bin/readlink", ["readlink", "/proc/1373/exe"], [/* 15 va=
rs */]) =3D 0
1377 execve("/usr/bin/tty", ["tty"], [/* 15 vars */]) =3D 0
1379 execve("/bin/uname", ["/bin/uname", "-n"], [/* 16 vars */]) =3D 0
1381 execve("/bin/uname", ["/bin/uname", "-m"], [/* 16 vars */]) =3D 0
1383 execve("/usr/bin/manpath", ["/usr/bin/manpath", "-q"], [/* 32 vars */=
]) =3D 0
1385 execve("/usr/bin/ls", ["ls", "/etc/bash_completion.d"], [/* 38 vars *=
/]) =3D 0
1387 execve("/usr/bin/tty", ["tty"], [/* 43 vars */]) =3D 0
1391 execve("/usr/bin/sed", ["sed", "-r", "s@/*:|([^\\\\]):@\\1\\n@g;H;x;s=
@/\\n@"...], [/* 48 vars */]) =3D 0
1395 execve("/usr/bin/sed", ["sed", "-r", "s@/*:|([^\\\\]):@\\1\\n@g;H;x;s=
@/\\n@"...], [/* 49 vars */]) =3D 0
1397 execve("/usr/bin/dircolors", ["/usr/bin/dircolors", "-b", "/etc/DIR_C=
OLORS"], [/* 53 vars */]) =3D 0
1399 execve("/usr/bin/tput", ["/usr/bin/tput", "hs"], [/* 55 vars */]) =3D=
0
1401 execve("/usr/bin/tput", ["/usr/bin/tput", "tsl"], [/* 55 vars */]) =
=3D 0
1403 execve("/usr/bin/tput", ["/usr/bin/tput", "fsl"], [/* 55 vars */]) =
=3D 0
1405 execve("/usr/bin/tput", ["tput", "sc"], [/* 55 vars */]) =3D 0
1407 execve("/usr/bin/tput", ["tput", "rc"], [/* 55 vars */]) =3D 0
1410 execve("/usr/bin/tty", ["tty"], [/* 55 vars */]) =3D 0
$ grep xauth sshd.tr
$=20
The problem is LOCAL on FreeBSD.
Any ideas to nail this down?
Thanks
matthias
--=20
Matthias Apitz, =E2=9C=89 guru@unixarea.de, http://www.unixarea.de/ +49-176=
-38902045
Public GnuPG key: http://www.unixarea.de/key.pub
May, 9: =D0=A1=D0=BF=D0=B0=D1=81=D0=B8=CC=81=D0=B1=D0=BE =D0=BE=D1=81=D0=B2=
=D0=BE=D0=B1=D0=BE=D0=B4=D0=B8=D1=82=D0=B5=D0=BB=D0=B8! Thank you very much=
, Russian liberators!
--gKMricLos+KVdGMg
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