To allow us to login to your Linux server, we use SSH Keys. That way, we do not need to have a password of your server. And you can instantly deny us access by removing our keys.
You can find our SSH keys here:
https://www.tuxis.nl/tuxis.pubkey
Add the contents of this file to ~user/.ssh/authorized_keys, where user is the username as who we may login.
Make sure that port 22 is open for the following IP-addresses/ranges:
IPv4
31.3.104.192/27
31.3.104.137
31.3.104.134
IPv6
2a03:7900:1:1::/64
2a03:7900:2:0:31:3:104:137
2a03:7900:64::/64
2a03:7900:2:0:31:3:104:134