Date: Sun, 14 Sep 2014 23:39:40 +0800 From: bycn82 <bycn82@gmail.com> To: Willem Jan Withagen <wjw@digiware.nl>, Ian Smith <smithi@nimnet.asn.au> Cc: "Alexander V. Chernikov" <melifaro@freebsd.org>, Freddie Cash <fjwcash@gmail.com>, freebsd-ipfw@freebsd.org Subject: Re: IPFW rule sets and automatic rule numbering Message-ID: <5415B6BC.4090604@gmail.com> In-Reply-To: <54158E49.7090102@digiware.nl> References: <CAOjFWZ4rx4FAc4AoPw3d=cSg4-z_QOWEF=phkT2PuzfUjn0y5A@mail.gmail.com> <CAOjFWZ6i1%2BgCZ9jMnBNEGqL7airdxN3d=B0__Z_Zj1gGG4APKg@mail.gmail.com> <541469D4.6070107@gmail.com> <CAOjFWZ749EazFz1prFRfidp9bqmqO%2B=%2BXFsu7mVtE%2Bnq2CxwKw@mail.gmail.com> <54156FBB.1030907@digiware.nl> <20140914204055.K61666@sola.nimnet.asn.au> <54158E49.7090102@digiware.nl>
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On 9/14/14 20:47, Willem Jan Withagen wrote: > On 14-9-2014 13:44, Ian Smith wrote: >> On Sun, 14 Sep 2014 12:36:43 +0200, Willem Jan Withagen wrote: >> > On 13-9-2014 21:51, Freddie Cash wrote: >> > > You can replicate it using 3 rules, loaded into two sets: >> > > >> > > ipfw set disable 1 >> > > ipfw add allow ip from any to any >> > > ipfw add 65524 allow ip from any to any >> > > ipfw add allow ip from any to any >> > > ipfw set swap 1 0 >> > > >> > > Run that two or 3 times. Every rule will be numbered 65534 after the 2nd or >> > > 3rd run. >> > >> > > >> > > I expected it to be numbered 10, 65524, 65534 after every run. >> > > >> > > However, after reading the man page a few more times and thinking about it >> > > a little more, it makes sense that the numbering is global across all sets, >> > > as you can have multiple sets enabled simultaneously. >> > > >> > > It just doesn't mesh with my desire to use auto numbering. I'm in the midst >> > > of manually numbering all my rules now. :) >> >> > This is easily circumvented by making shure that the first rule is >> > >> > ipfw add 10 ..... >> > like: >> > ipfw add count ip4 from any to any via vlan126 >> > (vlan126 is my outside connection) >> > And then you are home free. >> > >> > I actually use this to also separate diffent types of block by injecting: >> > ipfw add <blocknumber> count ip from any to any >> > >> > like: >> > 03000 713812041 425643462848 count ip from any to any >> > 03010 0 0 deny ip6 from fc00::/7 to any via vlan126 >> > >> > And the 3000 block contains all antispoofing and likes. >> >> I'd almost replied along the same lines - also tending to number first >> rules in a block and then add unnumbered rules until other sections - >> before realising that once Freddie had added his rule 65524, maybe in >> another set, it's game over; every unnumbered rule added after that is >> going to be >= 65524 and <= 65534. >> >> And even as you have it above, if you rerun your script again without >> flushing the entire ruleset, apart from specifically numbered rule/s, >> everything will get readded after the highest rule previously used. >> >> Alexander said: >> > I think we can consider implementing sysctl which permits per-set >> > auto-numbering. >> >> Perhaps rather than a separate high water mark per set that would be >> reset on set N flush - which I think is what Alexander means? - if one >> could set something like maybe 'net.inet.ip.fw.autoinc_last' which would >> default, as now, to the highest rule added so far, but could be reset to >> something else before adding more auto_inc rules? Might get tricky, and >> of course it has to not break older rule scripts - some VERY old :) > Could very well be. > I was for the same reason going to implement Freddy's strategy and swap > sets... So could be that I'd run into the same problem in near future. > > It is hard to imagine that people would depend on the fact that the last > rule used would survive a set swap, and actually build on it. > > Being able to actual set the last number used, aka the next number to be > assigned, would be equivalent to my trick using > 'ipfw add <num> count....' > to preset a certain startingpoint. > It could even be made into either a flag on ipfw like > -k keep the last index for future increment > or an ipfw instruction > ipfw setautoincr <num> > And that would not interfere with old scripts. > > tinkering it through sysctl would be possible too, but I'd prefer things > like this integrated in the command-interface. > > --WjW > > I think the per-set auto-numbering is a good idea. But we are there is because of the "set", the "set" in IPFW is a trouble maker. I stared to learn the IPFW in Apr this year, and I was disappoint on some features, and the "set" is one of them. I created a fix patch about it but not relevant to this topic. Regards, Bill Yuan
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