Networking & Security in Linux

Introduction

Networking and security are at the heart of DevOps. Today, I explored how Linux handles networking, manages security, and ensures secure remote access. These skills are crucial for server management, troubleshooting, and securing infrastructure.

What I Learned Today

1️⃣ Networking Basics

Understanding how Linux networks work is essential for managing cloud environments. I explored:

• Checking network configurations:

    ifconfig
    ip a
  

• Testing network connectivity:

    ping google.com
    traceroute google.com
  

• Viewing active network connections:

    netstat -tulnp
    ss -tulnp
  

2️⃣ Managing Network Services

I practiced controlling network services with:

• Restarting networking services:

    systemctl restart networking
  

• Checking domain name resolution:

    nslookup example.com
    dig example.com
  

3️⃣ Firewall & Security

Securing servers is crucial, so I learned about:

• UFW (Uncomplicated Firewall):

    ufw enable
    ufw allow 22/tcp
    ufw status
  

• iptables:

    iptables -A INPUT -p tcp --dport 80 -j ACCEPT
    iptables -L -v -n
  

4️⃣ Secure Remote Access

Managing remote servers requires secure access. I explored:

• Connecting securely with SSH:

    ssh user@server-ip
  

• Copying files remotely:

    scp file.txt user@server-ip:/home/user/
  

• Syncing directories with rsync:

    rsync -avz /local/path/ user@server-ip:/remote/path/
  

5️⃣ Troubleshooting Network Issues

For diagnosing issues, I practiced:

• Capturing network packets:

    tcpdump -i eth0
  

• Checking if a port is open:

    nc -zv server-ip 22
  

Interesting Things:

• Configuring firewall rules properly without blocking my own access.

• Understanding differences between iptables and ufw.

#DevOps #LinuxNetworking #CyberSecurity #100DaysOfDevOps

---