netcat tcp proxy, for mapping ports on a remote machine to a local machine

nc-proxy-readme.md

Helper script to map ports to other servers.

Use Case

had a database that was only accesible in the VPC on aws, so i created an dev intance and did a ssh tunnel to that dev instance with netcat mapping the port to the database

Sample Usage

Forward all request from local 5432 to remote host google.com port 80

./nc-proxy.sh 5432 google.com 80

Reference:

• http://serverfault.com/questions/457433/proxy-with-netcat-forever
• http://notes.tweakblogs.net/blog/7955/using-netcat-to-build-a-simple-tcp-proxy-in-linux.html

nc-proxy.sh

#!/bin/sh -e

if [ $# != 3 ]
then
    echo "usage: $0 <src-port> <dst-host> <dst-port>"
    exit 0
fi

TMP=`mktemp -d`
PIPE=$TMP/pipe
trap 'rm -rf "$TMP"' EXIT
mkfifo -m 0600 "$PIPE"

nc -k -l -p "$1" <"$PIPE" | nc "$2" "$3" > "$PIPE"

that worked when launched on a k8s pod, and then when I forward the port (kubectl port-forward) I'm then able to connect to a elasticache instance accessible only from the k8s cluster