How to kill a TCP connection using netstat

Home » Questions» Linux

Subscribe

Subscribe to mail newsletter

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:

tcpkill -i eth0 { expression }

Examples:

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

tcpkill -i eth0 port 21

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

tcpkill host 192.168.1.2

OR

tcpkill host host12.nixcraft.com


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

tcpkill ip host 192.168.1.2 and not 192.168.1.111

Since tcpkill expressions are based upon tcpdump command's filter expression, it is recommended that you read options with expression and examples.

cutter command

Cutter is an open source program that allows Linux firewall administrators to abort TCP/IP connections routed over Linux based firewall. It works on Linux router only. We have already covered examples of cutter here.

Related articles

Tips & Tricks | Email