---
# System prepended metadata

title: '[Melange] Documentation'

---

# [Lab Server] Everything You Need to Know about Melange

## :notebook_with_decorative_cover: Abstract

This document is all about how to become our next server admin. For any questions please do not hesitate to reach out in the Discord channel.


## :book: Background

To connect to our server, open the terminal on your laptop and type:

```shell
ssh <your_net_id>@melange.cs.northwestern.edu
```

## :feet: Step to Add New User
1. Run the following command

```shell
sudo adduser <username>
```

2. Make sure the user changes their password with `passwd` upon first login

## :warning: Common Troubleshooting Procedures

### :question: Server down/Cannot connect

1. Check if server is up by command

```shell
ping melange.cs.northwestern.edu
```

2. If no response, go to Aravindan's office and log into the server (reboot first if needed).
3. Check if `sshd` (OpenSSH Server) is up and running by

```{bash}
sudo /etc/init.d/ssh status
```

4. In necessary, restart `sshd` by

```
sudo sudo /etc/init.d/ssh restart
```

### :question: Adding new `sudo` access

:::danger

**NOTE: Only system admins should have sudo privilege.** 

If a user attempts to `apt` install something that requires root access, then they should not do it that way. Instead, they should only install packages in their own user space using an appropriate package manager which does not require root access. 

There are many ways to achieve this, for example [conda forge](https://conda-forge.org/) is one of the most recommended ways.

:::

1. Go to `/etc/sudoers.d`

2. Copy-and-paste one of the existing configs (e.g. `20_ate2041`) and create a new file

### :question: User forgot their password

:::success
**Best-practice: It is encouraged that users utilize [public-key authentication](https://www.digitalocean.com/community/tutorials/how-to-configure-ssh-key-based-authentication-on-a-linux-server) to login.**
:::

1. Run `sudo passwd <username>` to change their password.

### :question: All Admins forgot their password (This actually happened before)

1. Follow the steps outlined [here](https://askubuntu.com/questions/24006/how-do-i-reset-a-lost-administrative-password)

2. You may need to manually edit the GRUB script by pressing `e` as outlined in one of the answers above. 