Comment # 1 on bug 1190965 from Johannes Meixner

No - bypassing the firewall cannot be done
in any kind of automated way because any
automated bypassing of any security mechanism
makes the whole security mechanism useless.

See in particular the section
"It is crucial to not accept remote printing information
 from untrusted hosts" in
https://en.opensuse.org/SDB:CUPS_and_SANE_Firewall_settings

You need to setup the firewall so that it matches
your particular networking environment.