Linux file Maximum connection number problem---bash:ulimit:open files:cannot modify limit:operation not Permitted____linux

Problem Description:

Login system error,-bash:ulimit:open Files:cannot modify limit:operation not permitted

Last Login:thu Aug 14:42:27 from 10.6.90.41
-bash:ulimit:open Files:cannot Modify limit:operation not permitted
-bash:ulimit:open Files:cannot Modify limit:operation not permitted

Actually, there was a problem executing the ulimit command.

-bash-3.2$ ulimit-a
Core file size (blocks,-c) 0
Data seg Size (Kbytes,-D) Unlimited
Scheduling Priority (-e) 0
File size (blocks,-f) Unlimited
Pending Signals (I.) 1064960
Max locked Memory (Kbytes, L) 32
Max memory Size (Kbytes, M) Unlimited
Open files (-N) 1024
Pipe Size (bytes, p) 8
POSIX message queues (bytes,-Q) 819200
Real-time priority (-R) 0
Stack size (Kbytes,-s) 10240
CPU time (seconds,-t) unlimited
MAX User Processes (-u) 16384
Virtual Memory (Kbytes,-V) Unlimited
File locks (-X) Unlimited
-bash-3.2$
-bash-3.2$ ulimit-u 16384-n 65536
-bash:ulimit:open Files:cannot Modify limit:operation not permitted
-bash-3.2$

There are no problems with the related configuration

-bash-3.2$ cat/etc/security/limits.conf

#add by WJ for RAC
Oracle Soft Nproc 2047
Oracle Hard Nproc 16384
Oracle Soft Nofile 1024
Oracle Hard Nofile 65536
Grid Soft Nproc 2047
Grid hard Nproc 16384
Grid Soft Nofile 1024
Grid hard Nofile 65536

-bash-3.2$ Cat/etc/pam.d/login
#add by WJ for RAC
Session Required Pam_limits.so
-bash-3.2$
-bash-3.2$
-bash-3.2$ Cat/etc/profile
#add by WJ for RAC
if [$USER = "Oracle"] | | [$USER = "Grid"]; Then
if [$SHELL = "/bin/ksh"]; Then
Ulimit-p 16384
Ulimit-n 65536
Else
Ulimit-u 16384-n 65536
Fi
Umask 022
Fi

Reason analysis:

Because the problem occurs after the OpenSSH upgrade and only SSH logon occurs, there is a basic suspicion of SSH

Solution:

The problem is finally resolved, it is indeed an SSH version of the problem
Vi/etc/ssh/sshd_config
Set the Uselogin to Yes,
#UseLogin No
Uselogin ye
Reboot SSH Service
Service sshd Restart

Uselogin specific meaning is as follows, look after also not very understand
Uselogin
             whether to use Login (1) During the logon process for an interactive session. The default value is "no".
             x11forwarding will be banned because login (1) does not know how to handle Xauth (1) cookies. It
             should be noted that login (1) is prohibited for remote execution of commands.
             useprivilegeseparation , then it will be disabled after the authentication is complete.