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Anonymous Platypus
Asked: 2015-03-12 23:42:36 +0800 CST

Is it possible to encrypt the communications via netcat?

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I know that its possible to chat in linux terminal using netcat. I want to know whether it is possible to encrypt the netcat communications.

I did chat by listening on PC-1

nc -l 1234

And connecting to my IP on the other machine.

nc $IP 1234
command-line

2 Answers

  1. Best Answer

    It's possible - however I don't think nc does this itself: echo "Words" | gpg -e will produce an encrypted version on stdout; you can specify a receiving user as per usual.
    If you pipe this to another copy of gpg as gpg -d then it asks for a passphrase - this will be remembered for a period, so enabling a conversation.

    Therefore, echo "words" | gpg -e | nc target 4321 will send, and nc -l 4321 | gpg -d will listen.

    Also, see this question which is similar.

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  2. By itself netcat doesn't have encryption or authentication controls so while the traffic could be encrypted via OpenSSL or GnuPG with some clever piping and a bit if loops on the listening side, if you're on an untrustworthy network you might lose the race-condition to read using it and netcat doesn't allow multiple clients without clever scripting... but I'm not here to bash a tool but instead notify you of a Bash tool ;-)

    Note it's very experimental and you should really check out the Travis-CI build log to find out exactly what it does, hint open a second window/tab and follow along with the travis.yml enabled scripts to see every working/tested feature so far developed.

    Second hint, the following command examples are better in my experience with encrypting random strings.

    Var_input="$@"
Var_gpg_opts="--armor --batch --no-tty --recipient [email protected] --encrypt"
Var_log_file="${PWD}/output.enc
## Output to terminal
cat <<<"${Var_input}" | gpg ${Var_gpg_opts}
## Save output to file
cat <<<"${Var_input}" | gpg ${Var_gpg_opts} >> "${Var_log_file}"

    However, decryption of multi-armored output file is a bit trickier... so here's the link to the script written for that because it's a bit too long to post here.

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