Useful Networking Scripts

01-classify-host-int-ext.sh

#!/bin/bash

# Define a list of hostnames
HOSTS=(
"google.com:443"
 "amazon.com:443"

)

# Iterate through the list of hostnames
for hostname in "${HOSTS[@]}"; do

    IFS=":"
    read -a parts <<< "$hostname"


    # Get the IP addresses using 'host' command
    ip_addresses=$(host ${parts[0]} | awk '/has address/ {print $4}' | tr '\n' ',' | sed 's/,$//')

    # Check if 'host' command succeeded and if any IPv4 addresses were found
    if [ -z "$ip_addresses" ]; then
        echo "Could not resolve any IPv4 addresses for $hostname"
    else
        internal="false"
        for ip in $(echo "$ip_addresses" | tr ',' ' '); do
            if [[ "$ip" == 10.* ]]; then
                internal="true"
                break
            fi
        done

        if [ "$internal" == "true" ]; then
            echo "INTERNAL $hostname - $ip_addresses"
        else
            echo "EXTERNAL $hostname - $ip_addresses"
        fi
    fi
done

02-tcp-host-port-single.sh

#!/bin/bash

HOST=$1
PORT=$2

if [[ -z "$HOST" || -z "$PORT" ]]; then
  echo "Usage: $0 <host> <port>"
  exit 1
fi

timeout 1 bash -c "</dev/tcp/$HOST/$PORT" > /dev/null 2>&1

if [ $? -eq 0 ]; then
  echo "Connection to $HOST on port $PORT succeeded."
else
  echo "Connection to $HOST on port $PORT failed."
fi