From VyOS Wiki
Pyptables is the codename for the netfilter rule generator library.
It's supposed to output iptables-restore compatible format.
- Chain (maps to xtables chain)
- Rule (maps to xtables rule)
We need to identify the least common denominator between all xtables to decide which methods to add.
- add_condition(match_type, match_arguments) -- generic xtables condition without checking, also used internally by high-level methods