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rungix/gist:1e82aa10068fb2bb5c99cc8bc633218a

Forked from gerjantd/gist:9787489
Created June 5, 2017 11:35
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  1. @gerjantd gerjantd revised this gist Mar 26, 2014. 1 changed file with 13 additions and 0 deletions.
    13 changes: 13 additions & 0 deletions gistfile1.txt
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    CLIENT/SERVER MODEL
    It is quite simple to build a very basic client/server model using nc. On one console, start nc listening on a specific port for a connection. For example:

    $ nc -l 1234

    nc is now listening on port 1234 for a connection. On a second console (or a second machine), connect to the machine and port being listened on:

    $ nc 127.0.0.1 1234

    There should now be a connection between the ports. Anything typed at the second console will be concatenated to the first, and vice-versa. After the connection has been set up, nc does not really care which side is being used as a ‘server’ and which
    side is being used as a ‘client’. The connection may be terminated using an EOF (‘^D’).

    There is no -c or -e option in this netcat, but you still can execute a command after connection being established by redirecting file descriptors. Be cautious here because opening a port and let anyone connected execute arbitrary command on your site is
    DANGEROUS. If you really need to do this, here is an example:

    On ‘server’ side:
  2. @gerjantd gerjantd created this gist Mar 26, 2014.
    18 changes: 18 additions & 0 deletions gistfile1.txt
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    DANGEROUS. If you really need to do this, here is an example:

    On ‘server’ side:

    $ rm -f /tmp/f; mkfifo /tmp/f
    $ cat /tmp/f | /bin/sh -i 2>&1 | nc -l 127.0.0.1 1234 > /tmp/f

    On ‘client’ side:

    $ nc host.example.com 1234
    $ (shell prompt from host.example.com)

    By doing this, you create a fifo at /tmp/f and make nc listen at port 1234 of address 127.0.0.1 on ‘server’ side, when a ‘client’ establishes a connection successfully to that port, /bin/sh gets executed on ‘server’ side and the shell prompt is given to
    ‘client’ side.

    When connection is terminated, nc quits as well. Use -k if you want it keep listening, but if the command quits this option won't restart it or keep nc running. Also don't forget to remove the file descriptor once you don't need it anymore:

    $ rm -f /tmp/f