#!/bin/bash

trap 'cleanup; exit 1' SIGINT SIGTERM

red="\033[0;31m"

green="\033[0;32m"

yellow="\033[0;33m"

light_green="\033[38;5;50m"

reset="\033[0m"

option=""

hostname=""

local_port=""

remote_port=""

subdomain=""

alias=""

show_help() {

echo "A Bash script to establish HTTP, TCP, and SSH tunnels using Serveo."

echo ""

echo "Usage: $0 [OPTIONS]"

echo ""

echo "Options:"

echo " -o, --option 'http' or 'tcp' or 'ssh' "

echo " -h, --hostname Specify the hostname"

echo " -lp, --local-port Set the local port number"

echo " -rp, --remote-port Set the remote port number"

echo " -s, --subdomain Coustom subdomain of http tunnel"

echo " -a, --alias Assign an alias for ssh"

echo ""

echo " -H, --help Show this help message "

exit 0

}

while [[ $# -gt 0 ]]; do

case "$1" in

-o|--option)

if [[ -z "$2" || "$2" == -* ]]; then

echo "Error: -o|--option requires a value."

exit 1

fi

option="$2"

shift 2

;;

-h|--hostname)

if [[ -z "$2" || "$2" == -* ]]; then

echo "Error: -h|--hostname requires a value."

exit 1

fi

hostname="$2"

shift 2

;;

-lp|-p|--local-port)

if [[ -z "$2" || "$2" == -* ]]; then

echo "Error: -lp|--local-port requires a value."

exit 1

fi

local_port="$2"

shift 2

;;

-rp|--remote-port)

if [[ -z "$2" || "$2" == -* ]]; then

echo "Error: -rp|--remote-port requires a value."

exit 1

fi

remote_port="$2"

shift 2

;;

-s|--subdomain)

if [[ -z "$2" || "$2" == -* ]]; then

echo "Error: -s|--subdomain requires a value."

exit 1

fi

subdomain="$2"

shift 2

;;

-a|--alias)

if [[ -z "$2" || "$2" == -* ]]; then

echo "Error: -a|--alias requires a value."

exit 1

fi

alias="$2"

shift 2

;;

-H|--help)

show_help

;;

*)

echo "Unknown option: $1"

exit 1

;;

esac

done

cleanup() {

kill "$req_pid" 2>/dev/null

kill "$tunnel_pid" 2>/dev/null

kill "$tcp_pid" 2>/dev/null

kill "$ssh_pid" 2>/dev/null

kill "$timer_pid" 2>/dev/null

sleep 1

kill $(pgrep -t $(tty | sed 's/\/dev\///') ssh) 2>/dev/null #just for a final command to ensure all process are killed

}

#function to monitor serveo status

serveo_stat(){

for i in {1..3}; do

if curl -sf -I --connect-timeout 5 "https://serveo.net" &>/dev/null; then

return 0 # Success

fi

done

return 1 # Failure

}

# function to check network connection

check_network() {

local url="https://www.google.com/generate_204"

curl -sf -I --connect-timeout 5 "$url" &>/dev/null || \

curl -sf -I --connect-timeout 5 "$url" &>/dev/null

}

# to keep the http tunnel alive by sending periodic requests

keepalive() {

local url=$(echo "$1" | tr -d '\n\r' | xargs)

while true; do

curl -Is $url | head -n 1 &>/dev/null

sleep 120

done

}

reg_sshkey() {

printf "${yellow}To request a particular subdomain, you first need to register your SSH public key.\n\

To register, visit one of the addresses below to log in with your Google or GitHub account.\n\

After registering, you'll be able to request your subdomain the next time you connect to Serveo.${reset}\n"

if ls ~/.ssh/id_rsa >/dev/null 2>&1; then

cd ~/.ssh || exit

fingerprint=$(ssh-keygen -lf id_rsa | awk '{print $2}')

encodedFingerprint=$(echo "$fingerprint" | sed \

-e 's/:/%3A/g' \

-e 's/\//%2F/g' \

-e 's/+/%2B/g' \

-e 's/=/ %3D/g')

echo ""

echo "register with google account: https://serveo.net/verify/google?fp=$encodedFingerprint"

echo "register with github account: https://serveo.net/verify/github?fp=$encodedFingerprint"

exit 1

else

echo ""

printf "A valid SSH key not found. do you want to create one (yes/no): "

read input

if [[ "${input,,}" == "yes" || "${input,,}" == "y" ]]; then

ssh-keygen -t rsa -b 4096

cd ~/.ssh || exit

fingerprint=$(ssh-keygen -lf id_rsa | awk '{print $2}')

encodedFingerprint=$(echo "$fingerprint" | sed \

-e 's/:/%3A/g' \

-e 's/\//%2F/g' \

-e 's/+/%2B/g' \

-e 's/=/ %3D/g')

echo ""

echo ""

echo "register with google account: https://serveo.net/verify/google?fp=$encodedFingerprint"

echo "register with github account: https://serveo.net/verify/github?fp=$encodedFingerprint"

exit 1

elif [[ "${input,,}" == "no" || "${input,,}" == "n" ]]; then

exit 1

else

echo Invalid input

exit 1

fi

fi

}

httptunnel() {

local port=80

local temp_file; temp_file=$(mktemp /tmp/tempfileXXXXXX.txt)

if [[ -z "$subdomain" ]]; then

printf "${green}Establishing HTTP tunnel with random subdomain...${reset}\n"

ssh -nT -R "$port:$hostname:$local_port" serveo.net | stdbuf -oL awk 'NR==1 {print $5}' > "$temp_file" &

tunnel_pid=$!

else

printf "${green}Checking availability of subdomain '$subdomain'...${reset}\n"

if wget -q --spider "https://$subdomain.serveo.net"; then

printf "${red}Subdomain '$subdomain' is not available. Exiting.${reset}\n"

rm "$temp_file"

exit 1

fi

printf "${green}Establishing HTTP tunnel with subdomain '$subdomain'...${reset}\n"

ssh -nT -R "$subdomain:$port:$hostname:$local_port" serveo.net | stdbuf -oL awk 'NR==1 {print $5}' > "$temp_file" &

tunnel_pid=$!

fi

while true; do #put this in a loop for a reson. there might be delay in writing

if [[ -n "$link" ]]; then

url=$link

break

else

link=$(<"$temp_file")

fi

done

if [[ $link == 'subdomain,' ]]; then

cleanup

reg_sshkey

exit 1

else

printf "${green}HTTP tunnel established: ${light_green}$link${reset}\n"

fi

rm "$temp_file"

keepalive "$url" &

req_pid=$!

}

tcptunnel() {

local port="${remote_port:-0}"

if [[ "$port" -ne 0 ]] && ncat -zv serveo.net "$remote_port" &>/dev/null; then

printf "${red}Remote port $port is in use. Try again with other port number or keep it '0' to get assigned a random one Exiting.${reset}\n"

exit 1

fi

printf "${green}Establishing TCP tunnel on random remote port...${reset}\n"

ssh -nT -R "$port:$hostname:$local_port" serveo.net &

tcp_pid=$!

sleep 5

if ! ps -p $tcp_pid &>/dev/null; then

printf "${red}Failed to establish TCP tunnel. Exiting.${reset}\n"

exit 1

fi

printf "${green}TCP tunnel established successfully.${reset}\n"

}

sshtunnel() {

local port=22

printf "${green}Establishing SSH tunnel...${reset}\n"

ssh -T -R "$alias:22:$hostname:22" serveo.net &

ssh_pid=$!

sleep 5

if ! ps -p $ssh_pid &>/dev/null; then

printf "${red}Failed to establish SSH tunnel. Exiting.${reset}\n"

exit 1

fi

printf "${green}SSH tunnel established successfully.${reset}\n"

}

#a timer function to keep track of time

timer() {

counter=0

while true; do

counter=$((counter + 1))

sleep 1

echo "$counter" > /tmp/counter_value

done

}

maintain_tunnel(){

while true; do

if [[ -z "$killed" ]]; then

killed=0

fi

if [[ -z "$prob_exp" ]]; then

prob_exp=0

fi

if ! check_network ; then

printf "${red}Network connection lost.${reset}\n"

printf "${red}Waiting for connection...${reset}\n"

until check_network ; do

timer &

timer_pid=$!

prob_exp=1

if [[ $(cat /tmp/counter_value 2>/dev/null) -gt $1 ]] ; then

cleanup

killed=1

else

killed=0

fi

sleep 3

done

if [[ $killed -ne 1 ]]; then

cleanup

killed=1

fi

fi

if ! serveo_stat ; then

printf "${red}Either serveo.net or Network is down${reset}\n"

prob_exp=1

if [[ $killed -ne 1 ]]; then

cleanup

killed=1

fi

until serveo_stat;do

if ! check_network; then

continue 2

fi

sleep 5

done

fi

if [[ $prob_exp -eq 1 ]] ; then #run if connection prob(serveo or net down) was there

printf "${green}Connection restroed.${reset}\n"

printf "${green}Restarting tunnel...${reset}\n"

restart_tunnel $option $host $local_port $parameter

prob_exp=0

killed=0

fi

done

}

restart_tunnel() {

case "$opt" in

1)

httptunnel "$@"

;;

2)

tcptunnel "$@"

;;

3)

sshtunnel "$@"

;;

*)

printf "${red}Unknown tunnel option during restart. Exiting.${reset}\n"

exit 1

;;

esac

}

main() {

# Check if internet connection is available

if ! check_network; then

printf "${red}No internet connection. Exiting.${reset}\n"

exit 1

fi

# Check if Serveo is up

if ! serveo_stat; then

printf "${red}SERVEO IS DOWN. Exiting.${reset}\n"

exit 1

fi

if [[ -z $option ]]; then

printf "${red}Protocol not specified. Exiting.${reset}\n"

exit 1

fi

# condition for each case

case "$option" in

http)

opt=1

[[ -z "$local_port" ]] && { printf "${red}-lp | Local port not specified. Exiting.${reset}\n"; exit 1; }

httptunnel "$@"

;;

tcp)

opt=2

[[ -z "$local_port" ]] && { printf "${red}-lp | Local port not specified. Exiting.${reset}\n"; exit 1; }

tcptunnel "$@"

;;

ssh)

opt=3

[[ -z "$alias" ]] && { printf "${red}-a | Public hostname alias not specified. Exiting.${reset}\n"; exit 1; }

sshtunnel "$@"

;;

*)

printf "${red}Invalid protocol specified. use --help for more info ${reset}\n"

exit 1

;;

esac

maintain_tunnel 600

}

main "$@"