# SSH keys :key:

1. Create an SSH key pair with the following command:

    ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_ed25519_key -C "MyNewKey"

2. Add your newly generated Ed25519 key to an **SSH agent**:

    ssh-add ~/.ssh/id_ed25519_key

3. Copy the public key to Rackham or other server.

    ssh-copy-id -i .ssh/id_ed25519_key.pub rackham.uppmax.uu.se

4. Connect

    ssh [e-mail]

## On Bianca
- Add the content of your public key `id_ed25519_key.pub` to `$HOME/.ssh/authorized_keys`. **You can not** use the same command `ssh-copy` as in the case for Rackham i.e. you have to manually bring the key on Bianca.
If you paste it, **make sure it is in one line**, not wrapped/split over multiple lines.
- **Make sure the permissions look something like this**.

  ls -ld .ssh
  drwx--S--- 2 user user 4096 May  7  2019 .ssh

  ls -l .ssh
  total 1
  -rw-r----- 1 user user 743 May  7  2019 authorized_keys

- Connect to Bianca (*it is critical to use **SSH agent** in this case, see above*)

  ssh -A [e-mail]

- To debug, run with `-vv`

  ...
  debug1: Requesting authentication agent forwarding.
  debug2: channel 1: request [e-mail] confirm 0
  ...
  
  debug1: client_input_channel_open: ctype [e-mail] rchan 2 win 65536 max 16384
  debug1: client_request_agent: bound agent to hostkey
  debug2: fd 8 setting O_NONBLOCK
  debug1: channel 2: new [authentication agent connection]
  debug1: confirm [e-mail]
  Last login: Tue Jul 11 18:44:21 2023 from 172.18.144.254
   _   _ ____  ____  __  __    _    __  __
  | | | |  _ \|  _ \|  \/  |  / \   \ \/ /   | System:    sens2017625-bianca
  | | | | |_) | |_) | |\/| | / _ \   \  /    | User:      user
  | |_| |  __/|  __/| |  | |/ ___ \  /  \    | 
   \___/|_|   |_|   |_|  |_/_/   \_\/_/\_\   | 

    ###############################################################################

## WSL2 under Windows{10,11}

Here as a neat way to get persistent key-manger in WSL2 - credits: original [source](https://esc.sh/blog/ssh-agent-windows10-wsl2/).

sudo apt-get install keychain

Replace `XXXX` with the output of `hostname` command on the command line.

/usr/bin/keychain -q --nogui $HOME/.ssh/id_ed25519_key
source $HOME/.keychain/XXXX-sh

Remove `-q` to get some information if you want

 * keychain 2.8.5 ~ http://www.funtoo.org
 * Found existing ssh-agent: 4487
 * Known ssh key: /home/user/.ssh/id_ed25519_key

First time you login, you will be asked for the password and the key wil be handled by the key-manager. Check with

ssh-add -l
256 SHA256:wLJvQOM....   ....cTTtiU MyNewKey (ED25519)

## MobaXterm

In `MobaXterm` you can use the internal `MobAgent` or/and the `Peagent` from the `PuTTy` tools.


## OPTIONAL: SSH config

Example `$HOME/.ssh/config` file to make your work easier.

Host rackham
  User username
  HostName rackham.uppmax.uu.se
  ServerAliveInterval 240
  ServerAliveCountMax 2

# Default settings
#=======================================
Host *
  ForwardAgent no 
  ForwardX11 yes
  ForwardX11Trusted yes
  ServerAliveInterval 120
#=======================================

Now

# without config
ssh -Y [e-mail]
# with config
ssh rackham

# without config
scp local_file [e-mail]:remote_folder/
# with config
scp local_file rackham:remote_folder/

rsync ...
sftp ...

## Contacts:
- [Pavlin Mitev](https://katalog.uu.se/profile/?id=N3-1425)
- [UPPMAX](https://www.uppmax.uu.se/)
- [AE@UPPMAX - related documentation](/8sqXISVRRquPDSw9o1DizQ)


###### tags: `UPPMAX`, `ssh-key`