ssh -X remote does not work due to problem with xauth

[Matthias Apitz]

El día Wednesday, May 09, 2018 a las 10:35:36AM -0400, James B. Byrne via freebsd-questions escribió:

> 
> On Wed, May 9, 2018 06:47, Matthias Apitz wrote:
> >
> > 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 at 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 at 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 at r303343-amd64:/usr/obj/usr/src/sys/GENERIC  amd64
> >
> > $ truss -s128 -f -o ssh.tr ssh -X -vv apitzm at srap16dxr1
> > $ grep -i xauth ssh.tr > xauth.txt
> >
> > 20544: stat("/usr/local/bin/xauth",{ mode=-rwxr-xr-x
> > ,inode=2820147,size=41056,blksize=32768 }) = 0 (0x0)
> > 20544: write(2,"debug2: client_x11_get_proto: /usr/local/bin/xauth -f
> > /tmp/ssh-zfFpkwHgD1qj/xauthfile generate :0 MIT-MAGIC-COOKIE-1
> > untrusted t"...,153) = 153 (0x99)
> > 20545: execve("/usr/local/bin/xauth",0x801459260,0x801459408) = 0
> > (0x0)
> > 20545: stat("/tmp/ssh-zfFpkwHgD1qj/xauthfile-c",0x7fffffffdc40) ERR#2
> > 'No such file or directory'
> > 20545:
> > openat(AT_FDCWD,"/tmp/ssh-zfFpkwHgD1qj/xauthfile-c",O_WRONLY|O_CREAT|O_EXCL,0600)
> > = 3 (0x3)
> > 20545: pathconf("/tmp/ssh-zfFpkwHgD1qj/xauthfile-c",_PC_LINK_MAX) =
> > 32767 (0x7fff)
> > 20545:
> > link("/tmp/ssh-zfFpkwHgD1qj/xauthfile-c","/tmp/ssh-zfFpkwHgD1qj/xauthfile-l")
> > = 0 (0x0)
> > 20545: access("/tmp/ssh-zfFpkwHgD1qj/xauthfile",F_OK) ERR#2 'No such
> > file or directory'
> > 20545: open("/tmp/ssh-zfFpkwHgD1qj/xauthfile",O_RDONLY,0666) ERR#2 'No
> > such file or directory'
> > 20545: access("/tmp/ssh-zfFpkwHgD1qj/xauthfile",F_OK) ERR#2 'No such
> > file or directory'
> > 20545: write(2,"/usr/local/bin/xauth:  file
> > /tmp/ssh-zfFpkwHgD1qj/xauthfile does not exist\n",75) = 75 (0x4b)
> > 20545: access("/tmp/kde-guru/xauth-1001-_0",R_OK) = 0 (0x0)
> > 20545: open("/tmp/kde-guru/xauth-1001-_0",O_RDONLY,0666) = 4 (0x4)
> > 20545: write(2,"/usr/local/bin/xauth: (argv):1:  ",33) = 33 (0x21)
> > 20545: lstat("/tmp/ssh-zfFpkwHgD1qj/xauthfile-c",{ mode=-rw-------
> > ,inode=8331,size=0,blksize=32768 }) = 0 (0x0)
> > 20545: unlink("/tmp/ssh-zfFpkwHgD1qj/xauthfile-c") = 0 (0x0)
> > 20545: lstat("/tmp/ssh-zfFpkwHgD1qj/xauthfile-l",{ mode=-rw-------
> > ,inode=8331,size=0,blksize=32768 }) = 0 (0x0)
> > 20545: unlink("/tmp/ssh-zfFpkwHgD1qj/xauthfile-l") = 0 (0x0)
> > 20544: unlink("/tmp/ssh-zfFpkwHgD1qj/xauthfile") ERR#2 'No such file
> > or directory'
> > 20544: write(2,"Warning: untrusted X11 forwarding setup failed: xauth
> > key data not generated\r\n",78) = 78 (0x4e)
> >
> > Any ideas?
> >
> > Thanks
> >
> > 	matthias
> 
> You need the xauth pkg installed on the remote to generate the
> .Xauthority file for the ssh session.

The RPM is installed on the remote site:

apitzm at srap16dxr1:~> rpm -qa | grep xauth
xauth-1.0.8-1.51.x86_64
apitzm at srap16dxr1:~> which xauth
/usr/bin/xauth
apitzm at srap16dxr1:~> 

but the truss shows that the problem is on the local FreeBSD client
site.

	matthias

-- 
Matthias Apitz, ✉ guru at unixarea.de, ⌂ http://www.unixarea.de/  📱 +49-176-38902045
Public GnuPG key: http://www.unixarea.de/key.pub