ulimit error while changing max files to unlimited: PAM / sshd options?

[Rahul Nabar]

I tried changing the max limit on the number of open files but get an error:

ssh root at eu033
[root at eu033 ~]# ulimit -n unlimited
-bash: ulimit: open files: cannot modify limit: Operation not permitted

I verified that /etc/security/limits.conf has these two lines:
*               hard    nofile          unlimited
*               soft    nofile          unlimited

The default kernel limits seem high enough:
[root at eu033 ~]# cat /proc/sys/fs/file-max
1585781

[root at eu033 ~]# sysctl -a|grep fs.file-max
fs.file-max = 1585781

So why is my change via ulimit being rejected? What else could be
setting the limit at 1024. Any ideas how else I can get the file-limit
to be set to unlimited?

Actually, I am not even sure limits.conf is being used since I have
the following lines in the file /etc/ssh/sshd_config

UsePAM no
UsePrivilegeSeparation no

-- 
Rahul