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Using Socat and Netcat ​

socat stands for SOCket CAT, it is considered the advanced version of netcat. Both of these tools are useful for setting up and testing bidirectional data transfers over independent channels

Types of channels that can be used with socat

  • Files
  • Pipes
  • Devices (serial line, pesudo-terminal)
  • Sockets (UNIX, IP4, UDP, TCP)
  • SSL sockets
  • File descriptors (Stdin)

Syntax ​

netcat

sh
netcat [options] <host> <port>
netcat [options] <host> <port>

socat

sh
socat [options] <address> <address>
socat [options] <address> <address>

where each <address> follows the syntax protocol:ip:port.

Examples ​

Set up a dummy client-server on localhost

On one terminal, start a TCP listener on port 4444, forwarding the data to Stdout

sh
nc -l 4444
# or
socat TCP4-LISTEN:4444 STDOUT
nc -l 4444
# or
socat TCP4-LISTEN:4444 STDOUT

On another terminal, forward data from Stdin to port 4444 over TCP on localhost

sh
nc localhost 4444
# or
socat STDIN TCP:localhost:4444
nc localhost 4444
# or
socat STDIN TCP:localhost:4444

On the second terminal, type anything you like and see it appear on the other terminal.

Forward a UDP port to a serial device

socat UDP-L:4445 /dev/ttyUSB0
socat UDP-L:4445 /dev/ttyUSB0

All of the data arriving at UDP port 4445 will be forwarded to the serial device /dev/ttyUSB0

Tips ​

  • socat allows the shortcut address - to be used in place of Stdin/Stdout (e.g. socat TCP4-LISTEN:4444 -)

ADDITIONAL RESOURCES