Date: Thu, 10 May 2018 08:46:00 -0700 From: Bruce Ferrell <bferrell@baywinds.org> To: freebsd-questions@freebsd.org Subject: Re: ssh -X remote does not work due to problem with xauth Message-ID: <0b7b1b99-36cb-d22c-b2a2-84120f6f1359@baywinds.org> In-Reply-To: <20180510150154.GA2699@c720-r314251> References: <mailman.103.1525953601.52518.freebsd-questions@freebsd.org> <587e3b37-c5c7-4af2-80e2-f7c040a4d221@unixarea.de> <7edbad31-8ac8-9c27-2536-9a9a37a579b6@kicp.uchicago.edu> <20180510150154.GA2699@c720-r314251>
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On 5/10/18 8:01 AM, Matthias Apitz wrote:
> El día jueves, mayo 10, 2018 a las 09:38:16a. m. -0500, Valeri Galtsev escribió:
>
>>
>> On 05/10/18 09:00, Matthias Apitz wrote:
>>> On Thursday, 10 May 2018 14:34:27 CEST, James B. Byrne
>>> <byrnejb@harte-lyne.ca> wrote:
>>>> On Wed, May 9, 2018 14:09, Matthias Apitz wrote:
>>>>
>>>> What is the ownership of and permissions on .Xauthority on the remote
>>>> host?
>>>>
>>> It's owned by me, created as new if not there, but with size=0.
>> Did you check that you are not up against hard quota, and the filesystem
>> is not full? I already suggested that, but my message seems to miss your
>> attention. One thing you can try on remote host is:
> The remote host is one of our central development hosts, has not quota,
> no file sys full and plenty much GB of disk space:
>
> $ scp /boot/kernel/kernel apitzm@s70devl:.
> $ ssh apitzm@s70devl ls -lh kernel
> -r-xr-xr-x 1 apitzm apitzm 26M 10. Mai 16:49 kernel
> $ ssh apitzm@s70devl LANG=C df -kh .
> Filesystem Size Used Avail Use% Mounted on
> /dev/mapper/vg_root-lv_root 337G 68G 268G 21% /
>
>> Another possibility on multi-user system when this works for others but
>> not for you is if you as UNIX user is prohibited [X]-forwarding by
>> sysadmin (-"fascist"). I as sysadmin only twice during last decade had
>> to restrict one single user from doing something, but it still is the
>> possibility.
> I don't think, that our IT department does such things against the Tech Head
> I am :-)
>
> I do thank for all replies, but have to say, that all ignored the provided
> truss output (at least in all replies). Here it is again and shows that
> there is a LOCAL problem; the LOCAL /usr/local/bin/xauth tries to
> create the LOCAL file /tmp/ssh-adSkh4btDHWr/xauthfile (perhaps to move it over
> the SSH channel to the remote end) and it fails doing this:
>
> $ grep xauth ssh.tr
> 2505: stat("/usr/local/bin/xauth",{ mode=-rwxr-xr-x ,inode=15268663,size=41056,blksize=32768 }) = 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) = 153 (0x99)
> 2506: execve("/usr/local/bin/xauth",0x80145a260,0x80145a408) = 0 (0x0)
> 2506: stat("/tmp/ssh-adSkh4btDHWr/xauthfile-c",0x7fffffffdb80) ERR#2 'No such file or directory'
> 2506: openat(AT_FDCWD,"/tmp/ssh-adSkh4btDHWr/xauthfile-c",O_WRONLY|O_CREAT|O_EXCL,0600) = 3 (0x3)
> 2506: pathconf("/tmp/ssh-adSkh4btDHWr/xauthfile-c",_PC_LINK_MAX) = 32767 (0x7fff)
> 2506: link("/tmp/ssh-adSkh4btDHWr/xauthfile-c","/tmp/ssh-adSkh4btDHWr/xauthfile-l") = 0 (0x0)
> 2506: access("/tmp/ssh-adSkh4btDHWr/xauthfile",F_OK) ERR#2 'No such file or 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 or directory'
> 2506: write(2,"/usr/local/bin/xauth: file /tmp/ssh-adSkh4btDHWr/xauthfile does not exist\n",75) = 75 (0x4b)
> 2506: access("/tmp/kde-guru/xauth-1001-_0",R_OK) = 0 (0x0)
> 2506: open("/tmp/kde-guru/xauth-1001-_0",O_RDONLY,0666) = 4 (0x4)
> 2506: write(2,"/usr/local/bin/xauth: (argv):1: ",33) = 33 (0x21)
> 2506: lstat("/tmp/ssh-adSkh4btDHWr/xauthfile-c",{ mode=-rw------- ,inode=24961,size=0,blksize=32768 }) = 0 (0x0)
> 2506: unlink("/tmp/ssh-adSkh4btDHWr/xauthfile-c") = 0 (0x0)
> 2506: lstat("/tmp/ssh-adSkh4btDHWr/xauthfile-l",{ mode=-rw------- ,inode=24961,size=0,blksize=32768 }) = 0 (0x0)
> 2506: unlink("/tmp/ssh-adSkh4btDHWr/xauthfile-l") = 0 (0x0)
> 2505: unlink("/tmp/ssh-adSkh4btDHWr/xauthfile") ERR#2 'No such file or directory'
> 2505: write(2,"Warning: untrusted X11 forwarding setup failed: xauth key data not generated\r\n",78) = 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\bnistp256\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-Ck\M-*7\a\^U\^W\M-^\M^Il\M-n\M-,\0\0\0 M\M-G"...,8192) = 364 (0x16c)
> 2506: write(2,"couldn't query Security extension on display ":0"\n",50) = 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 untrusted timeout 1260
> /usr/local/bin/xauth: file /tmp/xauthfile does not exist
> /usr/local/bin/xauth: (argv):1: couldn't query Security extension on display ":0"
>
> This, and the fact that my colleagues 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.
>
> Thanks again for reading my post.
>
> matthias
Matthias,
I think this output is key:
couldn't query Security extension on display ":0"
xauth (at the sshd end) is attempting to interrogate the X server on the
ssh end and not getting an expected response, and as a result failing to
generate the necessary entries in the file xauth file.
searching the error on google found this:
https://groups.google.com/forum/#!topic/de.comp.os.unix.x11/44yHbl-RP_8
It has a nice step-by-step of what and how xauth is doing it's magic
Its the X server at the ssh end (your end). I suspect you'll find your
colleagues are using a somewhat different X server and that explains the
difference in your operation vs yours... And that corresponds to your
comment about the Xorg server.
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