129 lines
2.8 KiB
Markdown
129 lines
2.8 KiB
Markdown
# 🌐 Phase 2: Networking
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> Goal: Machines communicate — ping, SSH, file transfers, services
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---
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## 🎯 Exercise 1 — Ping & IPs
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```bash
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# Check your network
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ip addr show eth0
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ip route
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# Ping the other lab VM
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ping -c 4 10.0.1.2 # From alpine-1 → alpine-2
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ping -c 4 10.0.1.1 # From alpine-2 → alpine-1
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# Check ARP table
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ip neigh
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# tcpdump (packet capture) — Alpine needs install first
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apk add tcpdump
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tcpdump -i eth0 -c 5 icmp &
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ping -c 3 10.0.1.2
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```
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### 📝 Questions:
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1. What's the MAC address of the other VM?
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2. Can you ping alpine-hop (10.0.1.3) from alpine-1?
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3. What subnet are you on? How many usable hosts?
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---
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## 🎯 Exercise 2 — SSH Keys
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```bash
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# Step 1 — Generate an SSH key pair
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ssh-keygen -t ed25519
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# Press Enter for all prompts (no passphrase)
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# Step 2 — What just got created?
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ls -la ~/.ssh/
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# id_ed25519 ← your PRIVATE key (NEVER share this!)
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# id_ed25519.pub ← your PUBLIC key (safe to share)
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# Step 3 — Copy your public key to alpine-2
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ssh-copy-id root@10.0.1.2
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# Enter root password for alpine-2 when prompted
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# Step 4 — Test passwordless login!
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ssh root@10.0.1.2 'hostname; uptime'
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# Should work WITHOUT asking for a password 🎉
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# Step 5 — See what ssh-copy-id did
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ssh root@10.0.1.2 'cat ~/.ssh/authorized_keys'
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```
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### 💡 How it works
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Your public key is appended to `~/.ssh/authorized_keys` on the target. When you SSH, the server checks if you have the matching **private key** — no password needed! 🔑
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---
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## 🎯 Exercise 3 — File Transfer (SCP & RSYNC)
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```bash
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# SCP — single files
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echo "CCNA study notes" > /root/study.txt
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scp /root/study.txt root@10.0.1.2:/root/
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# Verify
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ssh root@10.0.1.2 'cat /root/study.txt'
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# RSYNC — directories (need to install on Alpine)
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apk add rsync
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rsync -av /root/lab/ root@10.0.1.2:/root/lab-backup/
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# Verify the backup
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ssh root@10.0.1.2 'ls -la /root/lab-backup/'
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```
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### 📝 Questions:
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1. What's the difference between `scp` and `rsync`?
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2. What does the `-a` flag in `rsync -av` mean? (hint: check `man rsync`)
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---
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## 🎯 Exercise 4 — Network Services
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```bash
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# Check what's listening on your VM
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ss -tlnp
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# Start a simple HTTP server on alpine-1
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python3 -m http.server 8080 &
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# Access it from alpine-2
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curl http://10.0.1.1:8080/
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# See the connection in your server logs
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# Kill the server when done
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kill %1
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```
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---
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## 🎯 Bonus: CCNA Challenge
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```bash
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# From alpine-1, can you SSH to alpine-hop?
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ssh root@10.0.1.3
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# Check the routing table
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ip route
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# Why can alpine-1 reach alpine-hop (10.0.1.3)?
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# Why can't alpine-1 reach the internet?
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```
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---
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## ✅ Phase 2 Checklist
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- [x] Ping and ARP (`ip neigh`)
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- [x] SSH key generation and passwordless login
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- [x] File transfer with `scp` / `rsync` (need `apk add rsync` on Alpine!)
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- [ ] Running a network service
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**Previous:** [[Phase 1 - Walking]] | **Next:** [[Phase 3 - Users and Files]]
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