1. Create a new, empty text file named 'Exec protect.txt'.
2. Copy and paste the text from here [github.com]into this text file.
3. Save the text file, then change its ending from '.txt' to '.cfg'. You should get a notice about changing the file type might lead to the content becoming gibberish; pretend you know what you're doing and confirm that.
4. Deploy the resulting 'Exec protect.cfg' file at your Steam/steamapps/"your username here"/teamfortress/tf/cfg folder.
5. Close everything and [re]start steam.
6. Try it out, go ahead and play a round of TF2 without being bothered by any server-side annoyances.