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Old 09-02-2003, 05:38 AM   #1
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Registered: Sep 2003
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Exclamation Redhat Linux login problem with non-root user

Hi there,

I have an SSH login problem with our newly installed RedHat Advanced Server 2.1 running on Dell PowerEdge 1750. I CAN SSH into it if I log in as root, however, if I try to log in as normal user, error message 'connection closed' will appear.

Anybody has encountered simliar problem? I don't think it's ssh problem, as I turn on sshd verbose level to DEBUG, sshd is not complaining anything. Instead, I believe it should have something to do with my PAM configuration, but I am new to PAM and cannot find anything wrong with those config files.

Here is my /etc/pam.d/sshd:

auth required /lib/security/ service=system-auth
auth required /lib/security/
account required /lib/security/ service=system-auth
password required /lib/security/ service=system-auth
session required /lib/security/ service=system-auth
session required /lib/security/
session optional /lib/security/

And here is my /etc/pam.d/system-auth:

# This file is auto-generated.
# User changes will be destroyed the next time authconfig is run.
auth required /lib/security/
auth sufficient /lib/security/ likeauth nullok
auth required /lib/security/

account required /lib/security/

password required /lib/security/ retry=3 type=
password sufficient /lib/security/ nullok use_authtok md5 shadow
password required /lib/security/

session required /lib/security/
session required /lib/security/

Besides, when I SSH in as root, I can find the following messages in sshd log, which are missing when I ssh in as normal user:

PAM establishing creds
channel 0: rfd 7 isatty
fd 7 setting O_NONBLOCK

Thanks in advance for your enlightenment.
Old 09-03-2003, 03:38 AM   #2
Registered: May 2001
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Haven't seen that prob. Checking these items next to what you've already shown would be the first things I'd do:
- SSH related: the /etc/ssh/ssh_ and sshd_ configs for DenyUsers or DenyGroups directives,
- PAM related: /etc/security/limits.conf for "login" directives for the user: if you limit those, make sure ssh-enabled users are allowed logins+1,
- TCP Wrappers: /etc/hosts.(deny|allow) for any IP, group or user based blocks.
Less common would be specific netfilter (iptables) rules using extensions like string or UID match, or IP blocks. While you're at it also check the users' ~/.ssh dir for right sig and config as well, even tho I can't imagine the problem to be in ~/.ssh.

If you ssh in as that user, specifying "-v -v -v" on the cmdline should give you all excessive and gory details of the connection and handshake buildup. Scrubbing IP addy's and posting the details *could* help.


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