Linux: How to kill a TCP connection using netstat?

You cannot kill a TCP connection using netstat utility. netstat is use for

  • Display network connections
  • Routing tables
  • Interface statistics
  • Masquerade connections
  • Multicast memberships
  • And much more

However Linux support two other commands or utility that can be used to kill a TCP connection.

tcpkill command

Use tcpkill command to kill specified in-progress TCP connections. It is useful for libnids-based applications which require a full TCP 3-whs for TCB creation.

Syntax:

Examples:

(a) Kill all outgoing ftp (port 21) connection:

(b) Kill all all packets arriving at or departing from host 192.168.1.2 (host12.nixcraft.com)

OR

(c) To kill all IP packets between 192.168.1.2 and any host except 192.168.1.111, type the following: