HUB

WAT

HUB or https://hub.xpub.nl is a VPN wonder to gazillions XPUB things.

You will need to:

• 0. Determine IP address of a new thing (see below)
• 1. Add a new thing (see below)
• 2. Ask user to give you preferred username & a new ssh pubkey (see below)
• 3. Add a new jump user (see below)
• 3. Jump user connects to his machine (see below)

Adding a new thing

Only gnd or a should do that. Also we will only add things that can only be ssh'ed via keys, no passwd logins plz.

• On xvm:

tinc -n hub invite ${NODE_NAME}

• On ${NODE_NAME}:

FIXME

Generating a ssh pubkey for the jump user

This should be done by the users themselves. This only applies to linux-like OS's. Users should be made aware what ssh keys are & etc. This generates a new key with a default name, so if the user already has an existing key, they should name it differently, so the existing one is not overwritten. They key should be protected by a passphrase.

ssh-keygen -t ed25519 -b 320 

Once the key is generated, we will need the public key (pubkey). Usually it would be a file called id_ed25519.pub located in ~/.ssh. Just cat the file and send us the contents. Please be aware there is also a file called id_ed25519. This is the private key. Dont ever send or disclose the private key !.

cat ~/.ssh/id_ed25519.pub

You can also send id_ed25519.pub as an attachment. If you named your key differently, it will be a file $NAME.pub

Adding a jump user on XVM

There is a script called add_jumpuser. It adds a new user on XVM, that is only allowed to ssh into the remote machine. You will need:

• Username for the user
• IP of the machine (see below for allocation)
• ED25519 pubkey from the user

Once you have all of this, just run on XVM (note the single quotes around the ssh pubkey):

/root/scripts/add_jumpuser.sh USERNAME IP 'PUBKEY'

eg.:
/root/scripts/add_jumpuser.sh lol 10.0.0.666 'ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIE29EOVCl0/WjknAoEEEZSPUyCWQKNoXX2HCC123456 some1@host'

When removing the user on XVM:

• userdel -r USERNAME
• remove USERNAME from AllowUsers in sshd_config
• restart sshd

IP allocation

• 1-9: XPUB main servers
• 10-99: shared machines used by the whole course (for admin or lessons or multi-user projects/libraries/etc)
• 100-254: personal and/or grad projects machines

Subnet       Node         ???
------       ----         ---
10.0.0.1     xvm          XPUB server, tincd overlord, destroyer of pads
10.0.0.10    skattkista   Borg Central
10.0.0.11    xpub2019     xpub1 sandbox (2019-2020) (Andre root)
10.0.0.100   wizardcity   Aymeric
10.0.0.101   screaming    Angeliki
10.0.0.102   warnet       Tash
10.0.0.???   food         Alice -- misconfigured, lost in ether

Connecting to the machines inside

On the user's personal machine (where the public key was generated) just:

ssh -j xpub.nl $IP

If for any reason it doesnt work, please send us the output of:

ssh -j xpub.nl $IP -vvv