158 lines
4.2 KiB
Markdown
158 lines
4.2 KiB
Markdown
# 🪴 Phase 1: Walking
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> Goal: Get comfortable with the Linux command line
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---
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## 🎯 Exercise 1 — Your First Commands
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SSH into **alpine-1** (through hop):
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```bash
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# Who am I?
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whoami # → root
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hostname # → localhost (or your hostname)
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uname -a # Show full system info
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uptime # How long since boot
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# Where am I?
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pwd # Print working directory
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ls -la / # List root directory contents
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# Make a file
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echo "Hello from Phase 1!" > /root/hello.txt
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ls -l /root/hello.txt # Check file details
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cat /root/hello.txt # Read the file
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```
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**Repeat on alpine-2 too!**
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✅ **Verified by Midori**
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---
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## 🎯 Exercise 2 — Navigation & File Basics
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```bash
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# Explore directories
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ls /
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ls /etc
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ls /var
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ls /home
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# Create a directory structure
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mkdir -p /root/lab/{notes,scripts,logs}
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ls -R /root/lab
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# Copy and move files
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cp /root/hello.txt /root/lab/notes/
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mv /root/hello.txt /root/lab/backup.txt
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# Read system files
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cat /etc/hostname
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cat /etc/os-release
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cat /etc/passwd
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# Answer these:
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echo $SHELL # What shell am I using?
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wc -l /etc/passwd # How many users?
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uname -r # Kernel version
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```
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### 📝 Questions to answer:
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1. What is your shell?
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2. How many users are listed in `/etc/passwd`?
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3. What kernel version are you running?
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---
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## 🎯 Exercise 3 — File Permissions
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```bash
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# Step 1 — Check current permissions
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ls -la /root/lab/
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# Step 2 — Understand the columns
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# -rw-r--r-- 1 root root 20 May 21 file
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# ─┬─ ─┬─ ─── permissions, owner, group, size, date, name
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# │ └── user/group/other (r=read, w=write, x=execute)
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# └── file type (-=file, d=directory)
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# Step 3 — Create a script
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# ⚠️ Alpine uses ash, NOT bash! Use #!/bin/sh
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mkdir -p /root/lab/scripts
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echo '#!/bin/sh' > /root/lab/scripts/sayhello.sh
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echo 'echo "Hello from a script!"' >> /root/lab/scripts/sayhello.sh
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# 🔴 If you use #!/bin/bash it will say "not found"!
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# Step 4 — Check permissions before making it executable
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ls -la /root/lab/scripts/sayhello.sh
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# Try to run it — should fail (no +x)
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./root/lab/scripts/sayhello.sh || echo "Failed! Need +x permission"
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# Step 5 — Add execute permission
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chmod +x /root/lab/scripts/sayhello.sh
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ls -la /root/lab/scripts/sayhello.sh
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./root/lab/scripts/sayhello.sh
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# Step 6 — Change permissions with numeric mode
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chmod 644 /root/lab/scripts/sayhello.sh
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ls -la /root/lab/scripts/sayhello.sh
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# Step 7 — Remove execute permission
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chmod -x /root/lab/scripts/sayhello.sh
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./root/lab/scripts/sayhello.sh || echo "Permission denied!"
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# Step 8 — Work with directories (need +x to enter)
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mkdir -p /root/lab/secret
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echo "classified" > /root/lab/secret/data.txt
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chmod 700 /root/lab/secret
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ls -la /root/lab/ | grep secret
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ls /root/lab/secret
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```
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### 📝 Questions:
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1. What does `ls -la` show? Describe each column.
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2. What does `+x`, `-x`, `644`, `755`, `700` mean?
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3. Why does a script need `+x` but `cat file.txt` doesn't?
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4. Why does a directory need `+x` to be accessible?
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---
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## 🎯 Exercise 4 — Text Editors
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```bash
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# Try nano (easier)
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nano /root/lab/notes/my-notes.txt
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# Type some text, Ctrl+O to save, Ctrl+X to exit
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# Try vi (classic)
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vi /root/lab/notes/vi-practice.txt
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# Press 'i' to insert, type something
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# Press Esc, then ':wq' to save and quit
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```
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---
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### 💡 Key Lesson: Root bypasses everything!
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- **root** can read/write/execute ANY file regardless of permissions
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- Permissions only protect against **non-root users**
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- Always use a regular user + `sudo` in production!
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- Directories need `+x` to be accessible
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### 🔢 Permission Cheat Sheet
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| Mode | Octal | Meaning |
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|------|-------|---------|
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| `rwx------` | `700` | Only owner can do anything |
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| `rwxr-xr-x` | `755` | Owner full, others read+execute |
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| `rw-r--r--` | `644` | Readable by all, writable by owner |
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| `rw-------` | `600` | Only owner can read/write |
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| `rw-rw-rw-` | `666` | Everyone can read/write (dangerous!) |
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## ✅ Phase 1 Complete Checklist
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- [x] Exercise 1: `whoami`, `uname -a`, file creation
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- [x] Exercise 2: Directory structure, `cp`, `mv`, `cat`
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- [x] Exercise 3: `chmod`, permissions understanding
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- ⏭️ Exercise 4: Skipped (already know text editors)
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**Next:** [[Phase 2 - Networking]] 🌐
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