Lab 1 - VPS setup

unix-decal-lab1

# Unix SysAdmin Decal
## Lab 1: Unix, the Shell, OSS {#lab1}
[Slides](https://ocf.io/decal/slides/1) and [lab](https://ocf.io/decal/labs/1) links for Tuesday 9-12-2017.
### Table of Contents {#toc}
1. [Create ssh key](#ssh-create)
2. [VPS hosting provider](#vps-hosting)
	- We'll be providing the machines, one of
		- Amazon Web Services
		- Google Cloud Platform - account provided by us
		- Digital Ocean
3. [Set up ssh key & login](#ssh-setup)
	- Set up ssh key / password
		- All command line
		- With web interface
		- `ssh-copy-id`
4. [Send feedback email](#feedback)
	- trouble encountered
	- favorite things learned from reading `man` pages

---
### 1. Create ssh key {#ssh-create}
Run the following command, and accept prompts in order to create an ssh keypair:

	ssh-keygen -t rsa -b 4096
Note: it's good practice to protect your ssh-keys with strong passwords, to protect against attackers who might briefly use...or completely steal...your computer.

`ssh-keygen` will create files `id_rsa`  and `id_rsa.pub` inside the `.ssh` directory.  View the file with `cat` or `less` later when viewing them to copy into a browser.
```
~ $ ls .ssh/
id_rsa id_rsa.pub
```
You can rename these files, but keep the public-private distinction, and make sure the base name matches (some tools expect this). Running `ssh-keygen -t rsa -b 2048` instead is OK too.

**Note**: 1024-bit RSA keys are considered too short nowadays. They are not *yet* broken, but have no margin for safety. DSA and it's cousin ECDSA are considered secure, but have some secondary security risks. I make it a policy not to use them, though I'll likely never be bitten by corner cases. New implementations of ssh include new algorithms. These are 


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### 2. VPS hosting provider {#vps-hosting}
**Enrolled students** will have a Virtual Private Server (VPS) hosted on Amazon Web Services (AWS) provided for them.

---
**Auditing users** may wish to acquire a VPS from Amazon, Google, or Digital Ocean. Free service credits for AWS and DigitalOcean may be claimed at [education.github.com/pack](https://education.github.com/pack) after creating/logging in to a GitHub account and associating it with a '.edu' email address. 

However, a VPS may not be required for the first few weeks of class, as many of the labs can be completed on our login server, tsunami, reachable at `tsunami.ocf.berkeley.edu` with the `ssh` command-line utility, or in a browser via the web-shell interface we provide at [ssh.ocf.berkeley.edu](https://ssh.ocf.berkeley.edu).

**Fun facts**:  We configure DNS so that `tsunami` and `ssh` are both valid names for our public login server, by resolving to the same IP address. `dig [host]` to see more.

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### 3. Set up ssh key & login {#ssh-setup}
- Set up ssh key / password
	- **All command-line** (e.g. from the OCF to VPS or your computer's shell to OCF or VPS, hereafter `[target]`). 
		1. Copy your public key, `id_rsa.pub` from where you created it to the server you want to have accept the key for authentication.
			- `scp .ssh/id_rsa.pub [target]:`
				- read `man scp`, the command uses `[host]:[path]`format, e.g. `ssh.ocf.io:~/.ssh/mbp_id.pub`
		2. Login to the target machine
			- `ssh infamous@ssh.ocf.io`
		3. Add your public key to the authorized keys file
 			- `cat id_rsa.pub >> .ssh/authorized_keys`
 		4. **Test it**
	 		- `ssh infamous@ssh.ocf.io` should not ask for a password.
	 		- *Extra: try `ssh -v` to see debug information*
	- **With web interface**
		1. `cat > public_key`
		2. Copy/Paste key from local to remote terminal
		3. `^D` - Control - D - EOF/End-of-File character.
		4. Proceed from step 2 of **All command line**.
	- The `ssh-copy-id` utility performs the same setup. 
		- Linux, Windows with Ubuntu users: it's available from your package manager. `apt install ssh-copy-id`
		- macOS users: [homebrew](https://brew.sh) will also allow you to install it with 1 command, `brew install ssh-copy-id`

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### 4. Send feedback email {#feedback}
  - [Email feedback and cool findings](mailto:lab1@decal.ocf.berkeley.edu)
	  - lab1@decal.ocf.berkeley.edu⧸⧸
	  - trouble encountered
	  - favorite things learned from reading `man` pages

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