Am Fri, 10 Jan 2020 14:31:40 +0100
schrieb Janne Johansson <[email protected]>:

> Den fre 10 jan. 2020 kl 13:58 skrev list <[email protected]>:
> 
> > > > There's a tunnel between Server A and Server B. Server A is a
> > > > standalone machine trying to reach over the VPN tunnel to a host
> > > > (10.0.1.50) that is located in a subnet of Server B. Setup is
> > > > the  
> >  
> 
> 
> > I appreciate the directions but after defining the exact same rules
> > as in the Tutorial (-> OpenBSD as roadwarrior) I still see the same
> > errors. This time I implemented it in a test environment.
> > Two testmachines:
> > Machine A wants to route all it's traffic through machine B.
> >
> > Machine A (192.168.22.222:
> > $ cat /etc/iked.conf
> > ikev2 'roadwarrior' active esp \
> >    from 0.0.0.0/0 to 0.0.0.0/0 \
> >    peer 192.168.22.110 \
> >    srcid <fqdn-of-a> \
> >    dstid <fqdn-of-b>
> >
> > $ cat /etc/pf.conf
> > match out on enc0 all nat-to 10.0.5.2
> >
> > Machine B (192.168.22.110)
> > $ cat /etc/iked.conf
> > ikev2 'responder' passive esp \
> >         from 0.0.0.0/0 to 10.0.5.0/24 \
> >         local egress \
> >         peer any \
> >         srcid <fqdn-of-b> \
> >         tag "ROADW"
> >
> > $ cat /etc/pf.conf
> > pass in on egress proto udp from any to 192.168.22.110 port {500,
> > 4500} tag IKED pass in on egress proto esp from any to
> > 192.168.22.110 tag IKED pass on enc0 tagged ROADW
> > match out on egress inet tagged ROADW nat-to egress
> >
> > This time there are no double packets to be seen on the interface.
> > There are still no responses coming back from packets sent over the
> > tunnel
> >
> > Machine B:
> > tcpdump -envps 1500 -i enc0
> > tcpdump: listening on enc0, link-type ENC 13:53:28.672605
> > (authentic,confidential): SPI 0xed1617dd: 192.168.22.222 > 192.16
> > 8.22.110: 10.0.5.2.65031 > <public-dns-ip>.53: [udp sum ok] 53436%
> > [1au] A? pool.ntp.org.(41) (ttl 64, id 10351, len 69) (ttl 64, id
> > 24158, len 89)                13:53:31.692533
> > (authentic,confidential): SPI 0xed1617dd: 192.168.22.222 > 192.16
> > 8.22.110: 10.0.5.2.65530 > <public-ip>.53: [udp sum ok] 25098%
> > [1au] A? pool.nt p.org.(41) (ttl 64, id 37930, len 69) (ttl 64, id
> > 48586, len 89) 
> 
> put tcpdumps on all the physical interfaces to see where packets
> "exit" and not just on the enc0, and look at them there,
> also it's not very clear what the test was here, only that a packet
> related to resolving stuff (given the <public-dns-ip>.53)
> and 10.0.5.2 doing something, which sort-of not matches "machine A
> wants all its traffic to go via Machine B" but rather some other
> purpose. Since 10.0.5.2 isn't Machine A or B, it gets a bit mixed up
> here, does it not?
> 

So, same config as before (-> exact same as in the faq roadwarrior to
responder szenario) 

Command on roadwarrior issued: nc -nvv <public-ip> 22

tcpdump on enc0 of roadwarrior:
$ tcpdump -envps 1500 -i enc0 | grep <public-ip>
tcpdump: listening on enc0, link-type ENC
14:50:10.306636 (authentic,confidential): SPI 0x76535e5a:
192.168.22.222 > 192.168.22.110: 10.0.5.2.59486 > <public-ip>.22: S
[tcp sum ok] 1404707663:1404707663(0) win 16384 <mss
1452,nop,nop,sackOK,nop,wscale 6,nop,nop,timestamp 1269250476 0> (DF)
(ttl 64, id 43924, len 64) (DF) (ttl 64, id 42206, len 84, bad ip cksum
0! -> f2b) 

tcpdump on enc0 of responder:
$ tcpdump -envps 1500 -i enc0 | grep <public-ip>
tcpdump: listening on enc0, link-type ENC
14:49:18.271228 (authentic,confidential): SPI 0x76535e5a:
192.168.22.222 > 192.168.22.110: 10.0.5.2.64558 > <public-ip>.22: S
[tcp sum ok] 3663687135:3663687135(0) win 16384 <mss
1452,nop,nop,sackOK,nop,wscale 6,nop,nop,timestamp 222997428 0> (DF)
(ttl 64, id 28669, len 64) (DF) (ttl 64, id 44672, len 84)

tcpdump on em0 (egress) of responder:
tcpdump -envps 1500 -i em0 | grep 94.16.120.200
tcpdump: listening on em0, link-type EN10MB
14:49:18.271272 00:0c:29:b7:74:5f e8:df:70:91:4e:6a 0800 78:
10.0.5.2.64558 > <public-ip>.22: S [tcp sum ok]
3663687135:3663687135(0) win 16384 <mss 1452,nop,nop,sackOK,nop,wscale
6,nop,nop,timestamp 222997428 0> (DF) (ttl 63, id 28669, len 64)

The lo traffic on the roadwarrior is bypassed using ipsec.conf

And the 10.0.5.2 is there on purposed as mentioned and described in the
FAQ: https://www.openbsd.org/faq/faq17.html#clientopenbsd

And yes the public ip I am trying to reach is up and available and
trying to connect to it with iked off works as expected.

g Stephan


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