Date: Sat, 18 Nov 2017 11:13:33 +0100 From: "Kristof Provost" <kristof@sigsegv.be> To: "Dave Horsfall" <dave@horsfall.org> Cc: "FreeBSD PF List" <freebsd-pf@freebsd.org> Subject: Re: Why is PF rejecting these connections? Message-ID: <80FABA34-F562-4158-B083-E1488345F249@sigsegv.be> In-Reply-To: <alpine.BSF.2.21.1711181201020.780@aneurin.horsfall.org> References: <alpine.BSF.2.21.1711181201020.780@aneurin.horsfall.org>
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On 18 Nov 2017, at 2:20, Dave Horsfall wrote: > I have PF (FreeBSD 10.4) configured to drop suspicious packets e.g. > those claiming to be ACKs for non-existent connections etc, but I'm > seeing some weirdness in the logs. Now, I sort of inherited the > configuration and don't fully understand each directive, but if it > works for someone I trust, well... > > Anyway, here are some sample log entries: > > 23:15:37.755870 IP host90-45-237-212.serverdedicati.aruba.it.34944 > > aneurin.kfu.smtp: Flags [S], seq 4161201091, win 14600, options [mss > 1460,sackOK,TS[|tcp]> > 23:15:40.755278 IP host90-45-237-212.serverdedicati.aruba.it.34944 > > aneurin.kfu.smtp: Flags [S], seq 4161201091, win 14600, options [mss > 1460,sackOK,TS[|tcp]> > [...] > 23:52:02.768939 IP rdns1.mailinfo.ga.43128 > aneurin.kfu.smtp: > Flags [S], seq 1022514539, win 14600, options [mss > 1460,sackOK,TS[|tcp]> > 23:52:18.768869 IP rdns1.mailinfo.ga.43128 > aneurin.kfu.smtp: > Flags [S], seq 1022514539, win 14600, options [mss > 1460,sackOK,TS[|tcp]> > Can you post a full pcap capture? It’s very hard to figure things out from a text summary of a packet. Where and how were these logged? How do you know they’re being dropped? > Etc; the common theme appears to be those options whose purpose I > don't quite grok, but are presumably legal in this context. > > The relevant lines from my pf.conf seem to be: > > set block-policy drop > set loginterface egress > #set ruleset-optimization basic > scrub in > block all > pass out quick all keep state > antispoof log quick for $ext_if inet > [ Sundry pass/block rules ] > Are these incoming or outgoing packets? I really can’t tell what’s going on from your report. Regards, Kristof
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