poff

poff [interface]

interface
    Optional. Specifies the interface to disconnect. If no interface is specified, it defaults to ppp0 or the interface name configured in the /etc/ppp/options file or the first interface found up and using pppd.

The poff command is used to terminate an active Point-to-Point Protocol (PPP) connection, typically used for dial-up Internet access. It effectively disconnects your computer from the Internet service provider (ISP) by shutting down the PPP interface.

The command works by bringing down the PPP interface specified in its configuration file (usually /etc/ppp/options and/or interface specific options files) and terminating the pppd process. This results in loss of network connectivity through that PPP interface. The poff command is often used in conjunction with the pon command, which establishes a PPP connection.

It is a simple and direct way to close the connection, freeing up resources and potentially preventing unwanted charges from your ISP. Proper use of poff ensures a clean disconnection and avoids potential data corruption.

If the pppd process is not running under the same user as poff, sufficient privileges (usually root) are required to terminate the process. Ensure the PPP configuration files are properly set up for the intended interface to avoid unexpected behavior.

If poff fails to disconnect the PPP connection, check the system logs (e.g., /var/log/syslog or /var/log/messages) for error messages. Ensure that the pppd process is actually running and that you have the necessary permissions to terminate it. Incorrect configuration of the PPP options can also cause disconnection problems.

poff has been a standard utility for managing PPP connections in Linux distributions for many years. Its development is closely tied to the development and widespread adoption of PPP for dial-up internet access. Originally created to simplify disconnecting the pppd process, the command provided a reliable and user-friendly interface for managing network connectivity. It remains relevant today, even with the decline of dial-up, as PPP is still sometimes used in other network configurations, like certain VPNs or embedded systems.

pon(1), pppd(8), chat(8)