Question : Login failed for user 'sa'. Reason: Password did not match that for the login provided.

What is the best way to stop an intruder trying to access a sqlserver database?
We do have a firewall and a strong -typed password for the 'sa' account, but it seems like every day, we see different people trying to access our database engine, with the 'sa' account.  We keep adding IP's to a block list, but that is getting old.
Thanks

Answer : Login failed for user 'sa'. Reason: Password did not match that for the login provided.

Some best practices:

1. Create one user with sysadmin privileges.
2. Disable sa account and use that account because people might try cracking sa user account which is well known to every one.
3. Set SQL Server to listen on port other than default port 1433
4. Enable SQL Server Browser if your SQL Server hosts more than one instance. Else disable SQL Server Browser Service and port 1434

Step 2 clearly would help you to solve your problem..