Secure a Linux VPS with a firewall on OneNet Servers
Applies to: Self-managed VPS customers who are comfortable managing Linux services directly.
This article explains the basic checks you should make before opening or closing ports on a OneNet VPS.
Before you start
- Confirm you still have SSH access before changing any firewall rule.
- Know which service and port you actually need to expose.
Steps on OneNet Servers
- List the ports that are already in use by your server before you change anything.
- Allow only the ports you need for your application and keep management access such as SSH restricted as tightly as possible.
- Test the new rules from a second session before you close your current shell.
- Save the rules in a way that survives reboot so the next restart does not reopen or remove them unexpectedly.
What you should see next
- The service you intended to expose should respond while unwanted ports remain closed.
- You should still be able to log back in after a reboot or service reload.
Common issues
- Locking yourself out is the most common firewall mistake.
- Application failures are often caused by the service not listening on the expected address, not just by the firewall itself.
When to contact support: Contact support only if the problem is network reachability at the infrastructure edge. Application-level firewall and OS rules remain a self-managed task unless your service includes management.
