If you don't already have a key pair, generate one (one-time, per
machine you'll connect from):

ssh-keygen -t ed25519 -C "your-name@your-institution"
# accept the default location (~/.ssh/id_ed25519)
# set a passphrase (recommended) — this protects the key on disk

This creates two files:

• ~/.ssh/id_ed25519 — private key. Never share this.
  Treat it like a password.
• ~/.ssh/id_ed25519.pub — public key. This is what you send
  to the admin.

Send the contents of the .pub file (it's a single line starting
with ssh-ed25519 ...) in your helpdesk ticket. Paste it inline;
do not attach as a file unless asked.

Once the admin adds your key, test the connection with verbose
output:

ssh -vv -p <port> <username>@<host>

If login fails, paste the last ~30 lines of the ssh -vv output
into the ticket — that's usually enough to diagnose the problem
(wrong port, wrong username, server config, key permissions on
your side, etc.).

Security notes:

• If you had an RSA key from before 2020, regenerate as ed25519
  — shorter, faster, and the modern default.
• Set strict permissions on the private key:
  chmod 600 ~/.ssh/id_ed25519. SSH refuses to use the key if
  it's world-readable.
• A single key pair can authorise you to many servers — no need
  to generate a new one per server.