Date: Tue, 1 Dec 2015 17:27:36 +0100 (CET) From: elof2@sentor.se To: Mark Felder <feld@FreeBSD.org> Cc: wishmaster <artemrts@ukr.net>, freebsd-net <freebsd-net@freebsd.org> Subject: Re: IPFW blocked my IPv6 NTP traffic Message-ID: <alpine.BSF.2.00.1512011702240.54839@farmermaggot.shire.sentor.se> In-Reply-To: <1448982333.1269981.454734633.11BA4DB2@webmail.messagingengine.com> References: <1448920706.962818.454005905.61CF9154@webmail.messagingengine.com> <1448956697.854911427.15is5btc@frv34.fwdcdn.com> <1448982333.1269981.454734633.11BA4DB2@webmail.messagingengine.com>
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On Tue, 1 Dec 2015, Mark Felder wrote: > > > On Tue, Dec 1, 2015, at 02:02, wishmaster wrote: >> >> Hi, Mark. >> >> >>> I'm hoping someone can explain what happened here and this isn't a bug, >>> but if it is a bug I'll gladly open a PR. >>> >>> I noticed in my ipfw logs that I was getting a log of "DENY" entries for >>> an NTP server >>> >>> Nov 30 13:35:16 gw kernel: ipfw: 4540 Deny UDP >>> [2604:a880:800:10::bc:c004]:123 [2001:470:1f11:1e8::2]:58285 in via gif0 Three long-shots: 1) I see that you use a gif interface. That makes me wonder: Do the 'keep-state' function in 'ipfw' work as bad as it does in 'pf'? In pf, 'keep state" doesn't keep state between software network interfaces and real network interfaces. So if I allow something in via tun0 (a software OpenVPN NIC), with keep state, the response is *not* automatically (via the state table) allowed back in on the ethernet NIC it was sent out. So for all my VPN-rules, I have to make two of them like this: Pf example: pass in quick on tun0 inet proto tcp from <trusted_networks> to <customer_nets> port 22 keep state label "VpnIN - SSH" pass out quick on em1 inet proto tcp from <trusted_networks> to <customer_nets> port 22 keep state label "DmzOUT - SSH" 2) Is this hapening over and over, or was it just a one time thing? If the latter, could it be that you flushed your firewall state table just after a cron job ran 'ntpdate 2604:a880:800:10::bc:c004', so the query got out but immediately after the state table was emptied and hence the response got blocked? 3) If 2001:470:1f11:1e8::2 is not the ipfw node itself, but some node behind it, could the ntp query to 2604:a880:800:10::bc:c004 have taken a different path? I.e. the ipfw node doesn't see the query, but the response packet is routed to it, so it gets blocked. /Elof
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