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Re: SSHD Fails with Exception


Like Jack Harris, I'm having problems with sshd under cygwin.  A few months 
ago I successfully installed cygwin, including sshd, on one WinNT system. 
I tried installing sshd on a different (but similarly configured) WinNT 
system this week, and find that I'm having the same sorts of problems as he 
reports.  Specifically:

sshd (run either in debug mode or as a daemon) accepts connections just 
fine and runs the user's shell as specified in /etc/passwd.  However, any 
attempt to run an external command (ls, etc.) results in an 
access_violation exception.

Interestingly, if I ssh and log in as the same user as is running sshd then 
all works just fine.  No access violation.  Aha, you say -- must be a 
rights problem.  Maybe so, but the user running sshd has all the rights 
that have been documented as being needed, including in particular
	Act as part of the operating system
	Increase Quotas
	Log on as a service
	Replace a process level token
(in addition, the user running sshd is part of the administrators group, 
and inherits the usual rights from that membership).

Additional data:  recent version of cygwin (1.1.8) and openssh (2.5.2p2-1. 
Upgrading to p2-3 didn't solve the problem either.).  User's home directory 
exists.  ntsec.  Only one copy of cygwin1.dll on the system.

There appears to be some magic here that isn't fully covered in the 
documentation.  It works for most people.  However, several people have 
reported similar problems on this list, in some cases reporting that the 
problem went away when they did something that might or might not have been 
related.  For example, Antonio Bernfica describes the same problem I'm 
seeing.  Someone else reported in March that similar problems had 
disappeared when he made sure that the target user's home directory 
existed.  I reported in January that I had resolved a similar problem by 
giving the sshd user the "Log in locally" right (I now believe incorrectly; 
my problems on that system went away, but I don't know what I did to 
resolve them.).  Those of us who are seeing the problem all believe that we 
are following the instructions in the documentation quite closely (though 
obviously we must not be).

Suggestions?

Here's the output for the exception (sshd -d as user "admin" in one window, 
then "ssh guest_sshd@localhost in another), and the result of running 
sygcheck:

$ pwd
/home/Guest_SSHD
$ ls
      0 [main] ?a 0 handle_exceptions: Exception: STATUS_ACCESS_VIOLATION
Exception: STATUS_ACCESS_VIOLATION at eip=61001B47
eax=00000001 ebx=75472F65 ecx=00000000 edx=75472F6D esi=00000000 
edi=0241FF40
ebp=0241FBF8 esp=0241FE98 program=?a
cs=001B ds=0023 es=0023 fs=0038 gs=0000 ss=0023
Stack trace:
Frame     Function  Args
0241FBF8  61001B47  (00000000, 00000000, 00000000, 00000000)
0241FEC0  61001B47  (0000008C, 77F10001, 0241FF10, 6100326E)
0241FF10  61003380  (00000000, 00000000, 77F76387, 77F7638F)
0241FF40  61003A3D  (0040172C, 00000000, 00000000, E1F8B018)
0241FF60  61003A7C  (00000000, 00000000, 7FFDB000, 805F2180)
0241FF90  0040F0DF  (0040172C, 8080EA40, 00000246, 8011748B)
0241FFC0  0040103D  (00000000, 00000000, 7FFDF000, 7FFDF000)
0241FFF0  77F1BA06  (00401000, 00000000, 000000B0, 00000100)
End of stack trace$ exit
Connection to localhost closed.
bash-2.04$ cygcheck -s

Cygnus Win95/NT Configuration Diagnostics
Current System Time: Sun Apr  8 15:25:00 2001

WinNT Ver 4.0 build 1381 Service Pack 5

Path:   /usr/local/bin
        /usr/bin
        /bin
        /cygdrive/c/Perl/bin
        /cygdrive/c/WINNT/system32
        /cygdrive/c/WINNT
        /cygdrive/c/Program Files/rksupport
        /cygdrive/c/Program Files/SSH Communications Security/SSH Secure 
Shell

SysDir: C:\WINNT\System32
WinDir: C:\WINNT

PWD = `/'
CYGWIN = `ntsec'
USER = `admin'
MAKE_MODE = `unix'
HOME = `/cygdrive/d/admin'

Use `-r' to scan registry

a:  fd           N/A    N/A
c:  hd  NTFS    4016Mb  62% CP CS UN PA FC
d:  hd  NTFS    5647Mb  11% CP CS UN PA FC     users
e:  cd           N/A    N/A

C:\cygwin\bin  /usr/bin  system  textmode
C:\cygwin\lib  /usr/lib  system  textmode
C:\cygwin  /        system  textmode
D:    /home    system  binmode

Found: C:\cygwin\bin\bash.exe
Found: C:\cygwin\bin\cat.exe
Found: C:\cygwin\bin\cpp.exe
Found: C:\cygwin\bin\find.exe
Found: C:\cygwin\bin\gcc.exe
Found: C:\cygwin\bin\gdb.exe
Found: C:\cygwin\bin\ld.exe
Found: C:\cygwin\bin\ls.exe
Found: C:\cygwin\bin\make.exe
Found: C:\cygwin\bin\sh.exe

   56k 2000/12/03 C:\cygwin\bin\cygbz21.0.dll
   82k 2001/01/21 C:\cygwin\bin\cygform5.dll
   18k 2000/10/23 C:\cygwin\bin\cyggdbm.dll
   17k 2001/01/07 C:\cygwin\bin\cyghistory4.dll
   14k 2000/10/23 C:\cygwin\bin\cygintl.dll
   81k 2000/12/05 C:\cygwin\bin\cygitcl30.dll
   35k 2000/12/05 C:\cygwin\bin\cygitk30.dll
   45k 2000/10/22 C:\cygwin\bin\cygjbig1.dll
  119k 2000/10/23 C:\cygwin\bin\cygjpeg6b.dll
   53k 2001/01/21 C:\cygwin\bin\cygmenu5.dll
  414k 2001/01/21 C:\cygwin\bin\cygncurses++5.dll
  299k 2001/01/21 C:\cygwin\bin\cygncurses5.dll
   34k 2001/01/21 C:\cygwin\bin\cygpanel5.dll
  163k 2001/02/03 C:\cygwin\bin\cygpng2.dll
  108k 2001/01/07 C:\cygwin\bin\cygreadline4.dll
  390k 2000/12/05 C:\cygwin\bin\cygtcl80.dll
    5k 2000/12/05 C:\cygwin\bin\cygtclpip80.dll
   10k 2000/12/05 C:\cygwin\bin\cygtclreg80.dll
  243k 2000/10/23 C:\cygwin\bin\cygtiff3.dll
  623k 2000/12/05 C:\cygwin\bin\cygtk80.dll
   41k 2000/11/20 C:\cygwin\bin\cygXpm-noX4.dll
   45k 2000/11/20 C:\cygwin\bin\cygXpm-X4.dll
   49k 2001/02/03 C:\cygwin\bin\cygz.dll
  615k 2001/01/31 C:\cygwin\bin\cygwin1.dll
    Cygwin DLL version info:
        dll major: 1001
        dll minor: 8
        dll epoch: 19
        dll bad signal mask: 19005
        dll old termios: 5
        dll malloc env: 28
        api major: 0
        api minor: 34
        shared data: 3
        dll identifier: cygwin1
        mount registry: 2
        cygnus registry name: Cygnus Solutions
        cygwin registry name: Cygwin
        program options name: Program Options
        cygwin mount registry name: mounts v2
        cygdrive flags: cygdrive flags
        cygdrive prefix: cygdrive prefix
        cygdrive default prefix:
        build date: Wed Jan 31 10:08:38 EST 2001
        shared id: cygwin1S3

Use -h to see help about each section

JQ Johnson                      Office: 115F Knight Library
Academic Education Coordinator  mailto:jqj@darkwing.uoregon.edu
1299 University of Oregon       phone: 1-541-346-1746; -3485 fax
Eugene, OR  97403-1299          http://darkwing.uoregon.edu/~jqj/

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