bindsess

bindsess is a command-line utility that allows users to bind or unbind specific TCP ports on a Linux system. It operates by manipulating the netfilter connection tracking system, specifically the nf_conntrack module. This enables the creation of persistent bindings for ports, meaning that even after a service that was using that port has been restarted or the system has been rebooted, the port remains associated with the specified process or a predefined mapping.

The primary use case for bindsess is to ensure that certain network services always bind to a particular port, even if the service itself doesn't explicitly request it or if there are conflicts. This can be useful in scenarios where multiple instances of the same application need to run, or when dealing with legacy applications that have fixed port requirements. The tool provides options to specify the target port, the process ID (PID) to which the port should be bound, or a target IP address.

bindsess can be used to query existing bindings, list all active bindings, and remove specific bindings. Its functionality relies on the availability of the nf_conntrack kernel module and appropriate permissions, typically root access, to modify network configurations. While it offers a way to manage port bindings, it's important to use bindsess with caution, as incorrect configurations could lead to network connectivity issues or conflicts with other services. Users should understand the implications of port binding before applying changes.