What is the differenence between set firewall filter and set firewall family

Question

I have some legacy Juniper routers. One set has firewall rules written as such:

set firewall filter ....

and the other set has rules written as:

set firewall family inet...

I know the second one is specific to inet traffic, but other than that is there any different between the two? If not, why have two different ways to write firewall rules on MX routers?

Answer 1

I know the second one is specific to net traffic, but other than that is there any difference between the two?

No.

jhead@R1# set firewall ?
Possible completions:
> filter               Define an IPv4 firewall filter

Contains IPv4 (protocol family inet).

jhead@R1# set firewall family ?
Possible completions:
> inet                 Protocol family IPv4 for firewall filter

Also contains IPv4 (protocol family inet).

If not, why have two different ways to write firewall rules on MX routers?

Older version of JUNOS used to only have "set firewall filter", and the newer versions contain "set firewall family" as well. So it was decided that it should stay for those who don't need to specify a family other than IPv4 (inet).

It does seem a bit backwards, but if you're not already, I would advise sticking to one style just to keep configuration as clear as possible.