Day 17 - Debian Package Management and Network Tools on Day 17

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Today’s DevOps journey focused on managing packages and performing network diagnostics on a Debian-based system. I worked with .deb packages using dpkg, handled dependency-aware installs with apt, managed users, and explored essential networking tools like dig, ss, and telnet.

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🧑‍💻 User Management & sudo Access

useradd devops
su - devops
userdel -r devops
adduser devops
id devops

🔐 Grant sudo access:

export EDITOR=vim
visudo

📦 Installing .deb Packages with dpkg

wget http://archive.ubuntu.com/ubuntu/pool/universe/t/tree/tree_1.7.0-3_amd64.deb
dpkg -i tree_1.7.0-3_amd64.deb
tree

Check or remove:

dpkg -l | grep tree
dpkg -r tree

📥 Using apt Properly

apt update
apt search tree
apt install tree

Install, remove & purge Apache:

🌐 Network Troubleshooting Tools

📍 traceroute or mtr

Trace the path packets take to a host:

traceroute google.com
mtr google.com

🧠 dig

DNS lookup tool:

dig google.com

Returns A records and DNS resolution path.

🧪 telnet

Test open ports:

telnet <IP> <PORT>

e.g. telnet 192.168.1.10 22 — useful for checking SSH access.

🔎 netstat (legacy) vs ss (modern)

netstat -antp | grep LISTEN
ss -tunlp

Shows listening ports, associated services, and open sockets.

🛣️ route -n

Display network gateways:

route -n

💡 What I Learned

• ✅ dpkg is for local .deb files, apt handles dependencies

• ✅ adduser vs useradd – interactive vs raw

• ✅ ss is a modern replacement for netstat

• ✅ dig, telnet, mtr = must-have tools for debugging connectivity

🌐 Real-World Use Cases Test if Jenkins or Apache is reachable

• Diagnose DNS misconfigurations

• Confirm firewall rules with telnet or ss

🔮 Next Steps

On Day 18, I plan to dive into cron jobs and automating system tasks like log backups or service checks.