#!/bin/sh

#This script was made with OpenVPN via-file in mind

#Location of the Approved Username/Password File
USERS="/somefolder/users"

#Check to see if username and password in the OpenVPN file has any special characters line by line
#Terminate script if special characters are used
while IFS= read -r line
do
    case "$line" in *[!-_a-zA-Z0-9]*) exit 1 ;; esac
done < "$1"

Username=`awk 'NR==1' "$1"`
Password=`awk 'NR==2' "$1"`

        HASHPASS=`echo -n "$Username$Password" | md5sum | sed s'/  -//'`
        i=0
        while [ $i -lt 10 ]; do
                HASHPASS=`echo -n $HASHPASS$HASHPASS | md5sum | sed s'/  -//'`
                i=`expr $i + 1`
        done

    if grep -q "$Username:$HASHPASS" $USERS; then
        echo "User Authenticated."
        exit 0
    fi

echo "Login credentials failed."
exit 1