ftppasv

ftppasv

#!/usr/bin/env bash
## Calculate the PASV port of an FTP server
##
## Example:
## ./ftppasv "227 Entering Passive Mode (0,0,0,0,148,75)"
## ./ftppasv 148 75
##
## Automatically calculate 148 * 256 + 75.
## Should echo "37963"

if [ $# -eq 0 ]; then
    echo "No arguments passed"
    exit 1
fi

calculate_port()
{
    echo "$(( $1 * 256 + $2 ))"
}

## "227 Entering Passive Mode (0,0,0,0,148,75)"
if [ $# -eq 1 ]; then
    P1=$(echo "$1" | cut -d ',' -f 5)
    P2=$(echo "$1" | cut -d ',' -f 6 | cut -d ')' -f 1)

    if [[ "$P1" == "" || "$P2" == "" || "$P1" == "$1" || "$P2" == "$1" ]]; then
        echo "Invalid argument"
        exit 1
    fi

    calculate_port $P1 $P2
fi

## 148 75
if [ $# -eq 2 ]; then
    calculate_port $1 $2
fi