On Tue, May 01, 2018 at 09:04:36PM +0800, Julian Elischer wrote: > On 1/5/18 2:02 am, Eugene Grosbein wrote: > >01.05.2018 0:48, Jeff Kletsky wrote: > > > >> From time to time, I rewrite my firewall rules to take advantages of the > >> ever-improving set of features that ipfw provides. One of the challenges > >> I have faced in the past was selecting packets that are generated on the > >> firewall host itself, as opposed to those that it received through an > >> interface. > >> > >>While I find most of the Linux firewall implementations untenable for a > >>variety of reasons, it does provide differentiation between what they > >>call "OUTPUT" and "FORWARD". I'm looking to see if there is a "better" > >>way to implement this kind of selection with the 11.1 version of ipfw. > >> > >>"out and not in" may years ago seemed an obvious selector, and it's good > >>to see that it is now clearly documented that it doesn't work in "man > >>ipfw" with "(in fact, out is implemented as not in)". > >> > >>"not recv any" doesn't seem to be helpful either > >> > >> $ sudo ipfw add 64000 count ip from any to any out xmit any not recv > >> any > >> 64000 count ip from any to any out > >> > >>In the past, I've tagged all incoming packets and used that tag to > >>differentiate between the two. > >> > >>Is there something "cleaner" (or perhaps clearer) that using a tag in > >>that way? > >I have been using "from me" for years and it works. > >If you have NAT, process "from me" packets before translating outgoing > >packets > >and process "to me" after translating incoming packet > On a host with two interfaces you can use subtraction.. > i.e in the outgoing part of the rules you can test on recv xxx0 and if > it doesn't match it must be locally generated. > I've also used the uid rule, which can only match on local packets > ut it only works if you only have a single 'user' on an appliance.
Why recv * not used for this task? _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
