Network Scripting with Shell Scripts

Introduction to Network Scripting

Network scripting involves automating tasks related to network configuration, monitoring, and management using shell scripts. These tasks can range from simple network diagnostics to complex configurations of network devices.

Basic Network Diagnostics

Let's start with some basic network diagnostic tasks that can be performed using shell scripts. These tasks include pinging a host, checking the network interface status, and displaying routing information.

Pinging a Host

#!/bin/bash

# Ping a host
HOST="google.com"
ping -c 4 $HOST
                

This script pings the host "google.com" 4 times and displays the results.

Checking Network Interface Status

#!/bin/bash

# Display network interfaces
ifconfig
                

This script displays the status of all network interfaces on the system.

Displaying Routing Information

#!/bin/bash

# Display routing table
netstat -rn
                

This script displays the routing table of the system.

Advanced Network Configuration

Advanced network configuration tasks can also be automated using shell scripts. These tasks include configuring IP addresses, setting up network interfaces, and managing firewall rules.

Configuring IP Address

#!/bin/bash

# Configure IP address
INTERFACE="eth0"
IP_ADDRESS="192.168.1.100"
NETMASK="255.255.255.0"
GATEWAY="192.168.1.1"

sudo ifconfig $INTERFACE $IP_ADDRESS netmask $NETMASK
sudo route add default gw $GATEWAY $INTERFACE
                

This script configures the IP address, netmask, and gateway for the specified network interface.

Setting Up Network Interfaces

#!/bin/bash

# Bring up the network interface
INTERFACE="eth0"
sudo ifconfig $INTERFACE up

# Bring down the network interface
sudo ifconfig $INTERFACE down
                

This script brings the specified network interface up and down.

Managing Firewall Rules

#!/bin/bash

# Allow incoming SSH connections
sudo ufw allow ssh

# Deny all incoming connections
sudo ufw default deny incoming

# Allow all outgoing connections
sudo ufw default allow outgoing

# Enable the firewall
sudo ufw enable
                

This script configures basic firewall rules using UFW (Uncomplicated Firewall).

Network Monitoring

Network monitoring is essential for ensuring the performance and security of your network. Shell scripts can be used to automate the monitoring of network traffic, bandwidth usage, and device status.

Monitoring Network Traffic

#!/bin/bash

# Monitor network traffic on interface eth0
sudo tcpdump -i eth0
                

This script uses tcpdump to monitor network traffic on the specified interface.

Monitoring Bandwidth Usage

#!/bin/bash

# Monitor bandwidth usage on interface eth0
IFACE="eth0"
vnstat -i $IFACE
                

This script uses vnstat to monitor the bandwidth usage on the specified interface.

Monitoring Device Status

#!/bin/bash

# Check if a host is up
HOST="192.168.1.1"
ping -c 1 $HOST > /dev/null 2>&1

if [ $? -eq 0 ]; then
    echo "$HOST is up"
else
    echo "$HOST is down"
fi
                

This script checks if a specified host is up by pinging it once.

Network Automation

Network automation involves using scripts to automate repetitive tasks, thereby reducing the potential for human error and improving efficiency. Here are some examples of network automation tasks that can be performed using shell scripts.

Automating Network Backups

#!/bin/bash

# Backup network configuration files
BACKUP_DIR="/backup/network"
CONFIG_FILES="/etc/network/interfaces /etc/hosts /etc/resolv.conf"

mkdir -p $BACKUP_DIR
cp $CONFIG_FILES $BACKUP_DIR
                

This script backs up important network configuration files to a specified directory.

Automating Network Health Checks

#!/bin/bash

# Define network hosts to check
HOSTS=("192.168.1.1" "192.168.1.2" "192.168.1.3")

for HOST in "${HOSTS[@]}"; do
    ping -c 1 $HOST > /dev/null 2>&1
    if [ $? -eq 0 ]; then
        echo "$HOST is up"
    else
        echo "$HOST is down"
    fi
done
                

This script checks the status of multiple hosts and prints whether each host is up or down.

Conclusion

Network scripting with shell scripts provides a powerful way to automate network configuration, monitoring, and management tasks. By following this tutorial, you can perform basic network diagnostics, configure network settings, monitor network performance, and automate network tasks using shell scripts. This automation helps ensure the efficiency, reliability, and security of your network.