UNIX for Advanced & Expert Users

On my small network some of my users are having trouble logging in. What's something that I can do to find out what's wrong? Are there any commands that I can run or files I can check?





,AP

Well, what's happeneing? The first thing to do is figure out if it's a network problem, or a server problem. Can they get to a login prompt? If so, what happens when they try to log in? Can you always reproduce the problem, or is it intermittant?

Sometimes it may happen that some users cannot get logins,

well please do the necessary steps for that.

1] Check the network connections using
ping <serverip> -t
2] On unix server machine check the following files as

/etc/hosts :- for host id of all machines who connected to
network
/etc/telnet :
/etc/telnet/init.d : to check telnet opctions.

well best of luck
from

Hey hey hey, you forgot the most important thing,
you should use programs like tcpdump (libpcap) or something to check the REAL connection (syn/ack flags), and easier, type ifconfig (or whatever used in your system) and look if there is a big number of overrun packages --> buy a new nic for the server...
HTH

There are a few other things that you may check also.

Does this affect ALL users or only a few people who have this problem repeatedly? OR is it random users during high activity on the box for user logins?



1) One very inobvious thing that I have had problems with is the number of ttys configured in my kernel.

If you only have 50 ports configured in the kernel, then when the 51st person attempts to login they will get varied errors. Like timeouts, being kicked off when they type their login, connection failed...



2) If you users are Telnetting from PCs, open a DOS window and ping from the user's machine to the IP for the box in question. If that works, then try to FTP to the box to see if that method will work.

From the box, use trace or traceroute if you have that on your box and give it a user's IP address to follow. This may help determine if you have a connection problem as well

If you can do all of these without errors, then your connection is not faulty.



3) The next thing to check is your security on the box, to see if the settings have changed.

Next, check your users' passwords and check for expired, inactivitiy, or locked out users because of too many failed logins.

As a last resort you may want to load a saved copy of your password file from a backup tape.

Hope that this helps you out.