O'Reilly logo

Linux in a Nutshell, 6th Edition by Robert Love, Stephen Figgins, Ellen Siever, Arnold Robbins

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Name

nc

Synopsis

nc [options] [host] [port]

TCP/IP command. nc (also known as netcat) is a versatile networking utility that reads and writes data across network connections using TCP or UDP. It’s a simple tool that has many uses. Unlike telnet, you can easily script nc. It can also be used to listen for as well as make connections.

Options

-C

Send CRLF as line ending.

-i seconds

Send and read data one line at a time with a delay of the specified interval in seconds. By default netcat reads and writes in 8 KB blocks.

-k

Listen for further connections when a current connection ends. Used with -l.

-l

Listen for an incoming connection on the specified port or ports.

-n

Don’t perform any DNS lookups.

-o file

Hex-dump data sent and received to file.

-p [port]

Read from the specified source port.

-r

Choose ports randomly.

-s [address]

Read from the specified source IP address.

-u

Use UDP instead of the default TCP.

-U

Use Unix Domain Sockets instead of the default TCP.

-v

Verbose output. Use multiple times to increase verbosity. If not using -n, include reports on forward/reverse DNS mismatches.

-w seconds

Set the inactivity timeout for a connection. Silently close a connection if idle for more than the specified seconds.

-x address[:port]

Use the proxy found at the specified IP address and port. If no port is specified, the well-known port for the protocol is used.

-X protocol

Use the specified proxy protocol. Valid values are 4 (SOCKS v. 4), 5 (SOCKS v. 5) and connect (HTTPS proxy). The default value is 5.

-z

Scan for ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required