Is there an echo server I can use to test my programs?

Question

I'm writing a simple client to ping a server with a packet on port 7 (echo) and then waiting for a reply. Is there a server that I can use to test this?

Answer 1

sudo nc -vvlp 7 -e /bin/cat

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If you happen to have a inetd installed, most of them have echo built-in. Snippet from /etc/inetd.conf:

echo   stream  tcp nowait  nobody  internal
echo    dgram   udp wait    nobody  internal

Answer 2

Here is a simple echo server:

sudo socat PIPE TCP-LISTEN:7,fork