NTP is set up on most servers by default, and not having it set up will most likely not break things.

Swapfile can be useful, but yet again, mostly set up by default anyway. Just type swapon -s to see if any swapfiles are present. If not, you can follow the swapfile tutorial.


Please note that the original text said "After this, you should configure a firewall", which implies that you should, indeed, only follow the part that mentions "firewall" from that tutorial.