Portscanner nur mit Linuxboardmitteln

Einfache sequentielle Methode

#!/bin/bash
HOST="$1"
for PORT in $(seq 1 1024); do
    if (echo >/dev/tcp/$HOST/$PORT) 2>/dev/null
      then
        echo "OPEN: $PORT"
    fi
done

Multithread Methode

#!/bin/bash
HOST="$1"
START="$2"
STOP="$3"
THREADS=50   # Anzahl paralleler Jobs

scan_port() {
    PORT="$1"
    (echo >/dev/tcp/$HOST/$PORT) >/dev/null 2>&1
    if [ $? -eq 0 ]; then
        echo "Host: $HOST - Port: $PORT open"
    fi
}

export -f scan_port
export HOST

seq $START $STOP | xargs -P $THREADS -I{} bash -c 'scan_port "$@"' _ {}