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Date:      Fri, 27 Nov 2015 10:13:49 +0100
From:      Daniel Bilik <ddb@neosystem.org>
To:        Gary Palmer <gpalmer@freebsd.org>
Cc:        freebsd-net@freebsd.org
Subject:   Re: Outgoing packets being sent via wrong interface
Message-ID:  <20151127101349.752c94090e78ca68cf0f81fc@neosystem.org>
In-Reply-To: <20151125122033.GB41119@in-addr.com>
References:  <20151120155511.5fb0f3b07228a0c829fa223f@neosystem.org> <C1D7F956-81C9-4ED4-99B8-E0C73A3ECB37@FreeBSD.org> <20151120163431.3449a473db9de23576d3a4b4@neosystem.org> <20151121212043.GC2307@vega.codepro.be> <20151122130240.165a50286cbaa9288ffc063b@neosystem.cz> <20151125092145.e93151af70085c2b3393f149@neosystem.cz> <20151125122033.GB41119@in-addr.com>

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On Wed, 25 Nov 2015 12:20:33 +0000
Gary Palmer <gpalmer@freebsd.org> wrote:

> route -n get <unreachable IP>

As suggested by Kevin and Ryan, I set the router to drop redirects...

net.inet.icmp.drop_redirect: 1

... but it happened again today, and again affected host was 192.168.2.33.
Routing and arp entries were correct. Output of "route -n get"...

   route to: 192.168.2.33
destination: 192.168.2.0
       mask: 255.255.255.0
        fib: 0
  interface: re1
      flags: <UP,DONE,PINNED>
 recvpipe  sendpipe  ssthresh  rtt,msec    mtu        weight    expire
       0         0         0         0      1500         1         0 

... has not changed during the problem.

Interesting was ping result...

PING 192.168.2.33 (192.168.2.33): 56 data bytes
ping: sendto: Operation not permitted
ping: sendto: Operation not permitted
...
64 bytes from 192.168.2.33: icmp_seq=11 ttl=128 time=0.593 ms
ping: sendto: Operation not permitted
...
64 bytes from 192.168.2.33: icmp_seq=20 ttl=128 time=0.275 ms
64 bytes from 192.168.2.33: icmp_seq=21 ttl=128 time=0.251 ms
ping: sendto: Operation not permitted
...
64 bytes from 192.168.2.33: icmp_seq=40 ttl=128 time=0.245 ms
ping: sendto: Operation not permitted
64 bytes from 192.168.2.33: icmp_seq=42 ttl=128 time=7.111 ms
ping: sendto: Operation not permitted
...
--- 192.168.2.33 ping statistics ---
46 packets transmitted, 5 packets received, 89.1% packet loss

It seems _some_ packets go the right interface (re1), but most
try to go wrong (re0) and are dropped by pf...

00:00:01.066886 rule 53..16777216/0(match): block out on re0: 82.x.y.50 > 192.168.2.33: ICMP echo request, id 58628, seq 39, length 64
00:00:02.017874 rule 53..16777216/0(match): block out on re0: 82.x.y.50 > 192.168.2.33: ICMP echo request, id 58628, seq 41, length 64
00:00:02.069634 rule 53..16777216/0(match): block out on re0: 82.x.y.50 > 192.168.2.33: ICMP echo request, id 58628, seq 43, length 64

And again, refreshing default route (delete default / add default)
resolved it...

PING 192.168.2.33 (192.168.2.33): 56 data bytes
64 bytes from 192.168.2.33: icmp_seq=0 ttl=128 time=0.496 ms
64 bytes from 192.168.2.33: icmp_seq=1 ttl=128 time=0.226 ms
64 bytes from 192.168.2.33: icmp_seq=2 ttl=128 time=0.242 ms
64 bytes from 192.168.2.33: icmp_seq=3 ttl=128 time=0.226 ms

--
						Dan



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