Troubleshooting User Session Limit: Access Denied Error in Rocky Linux 8.5
When working with a Linux server running Rocky Linux 8.5, you may encounter an issue where a user with a valid ID tries to connect to the server but receives an "access denied" error, with the message "Remote side unexpectedly closed the network connection." One possible cause of this issue is reaching the maximum number of user sessions allowed on the server. This article will help you understand the key concepts related to user session limits and troubleshoot the access denied error on your Rocky Linux 8.5 server.
User Session Limit: Understanding the Concept
A user session limit restricts the number of simultaneous connections that a user can have to a server. This limit helps prevent overloading the server, ensuring stable performance, and improving system security. In Rocky Linux 8.5, user session limits are controlled through several configuration files and system settings. The primary configuration file governing these settings is /etc/security/limits.conf.
Access Denied Error: Diagnosing the Issue
The access denied error with the message "Remote side unexpectedly closed the network connection" often occurs when a user has reached the maximum permitted number of simultaneous sessions. In some cases, this limit may be due to limitations imposed by the system administrator, or it could result from system-wide limits.
Checking and Modifying User Session Limits
To view the current user session limits, you can access the /etc/security/limits.conf configuration file. This file uses a specific format to define user limits. Each line contains a combination of user, group, and domain specifications, followed by a type of limit (soft or hard) and its value.
Example:
@student - maxlogins 4
To modify the user session limit, you need to edit the /etc/security/limits.conf file. You can use a text editor like vi or nano for this purpose.
Example: To allow unlimited login attempts for user 'john', add the following line to the file:
john - maxlogins unlimited
Additional System Limits
Some other system settings and configuration files can contribute to user session limits. These include:
/etc/pam.d/system-auth: This file defines the Pluggable Authentication Modules (PAM) for various system authentication tasks. You can edit this file to modify user authentication settings./etc/profile: The default shell profile for new users. You can customize this file to set specific user limits or system configurations related to user sessions./etc/sysctl.conf: Controls system settings related to kernel parameters and system behavior. You can use this file to modify network and system settings related to user sessions, such as maximum number of open files or sockets.
Resetting Maximum Connections for SSH
In some cases, the user session limit issue might be specific to SSH connections. To resolve this, you can modify the /etc/ssh/sshd_config file to increase the number of allowed SSH connections. Resetting the MaxStartups value can help with this problem. For example, you can change the value to 100:30:100 to allow up to 100 simultaneous SSH connections.
Note: Remember to restart the SSH service after making changes to the sshd_config file.
Command: systemctl restart sshd
- Understand the user session limit concept and its purpose in server stability and security.
- Diagnose the access denied error when reaching the maximum number of user sessions allowed.
- Learn how to modify user session limits and other system limits in Rocky Linux 8.5.
- Learn to increase the number of allowed SSH connections for resolving access denied errors.