pfsync(4) explains this:
"… The pfsync interface will attempt to collapse multiple state updates into
a single packet where possible. The maximum number of times a single
state can be updated before a pfsync packet will be sent out is
controlled by the maxupd parameter
…"
and
"… Where more than one firewall might actively handle packets, e.g. with
certain ospfd(8), bgpd(8) or carp(4) configurations, it is beneficial to
defer transmission of the initial packet of a connection. The pfsync
state insert message is sent immediately; the packet is queued until
either this message is acknowledged by another system, or a timeout has
expired. This behaviour is enabled with the defer parameter to
ifconfig(8).
…"
Eg. "defer: on", yours is "off".
//mxb
On 2 jul 2013, at 21:54, Loïc BLOT <loic.b...@unix-experience.fr> wrote:
> Hi all
> I have a strange issue (or i haven't read pfsync correctly but i don't
> think this is the problem :D)
>
> I'm using 2 OpenBSD as BGP+OSPF routers at the border of one site.
>
> Those BGP routers are secure with strong PF in stateful mode, and the
> stateful is working very well on each router. Because of my full mesh
> BGP configuration, the outgoing layer 7 sessions can leave my network by
> one router and responses can income by the other.
>
> To resolve this issue, i have created a dedidated VLAN for the pfsync
> traffic and attached pfsync to this VLAN.
>
> Here is a sample output of ifconfig on my first router:
>
> vlan995: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> lladdr a0:36:9f:10:4a:a6
> priority: 0
> vlan: 995 parent interface: trunk1
> groups: vlan
> status: active
> inet6 fe80::a236:9fff:fe10:4aa6%vlan995 prefixlen 64 scopeid
> 0x10
> inet 10.117.1.129 netmask 0xfffffff8 broadcast 10.117.1.135
> pfsync0: flags=41<UP,RUNNING> mtu 1500
> priority: 0
> pfsync: syncdev: vlan995 maxupd: 255 defer: off
> groups: carp pfsync
>
> And here on my second router:
>
> vlan995: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> lladdr a0:36:9f:17:e2:1e
> priority: 0
> vlan: 995 parent interface: trunk1
> groups: vlan
> status: active
> inet6 fe80::a236:9fff:fe17:e21e%vlan995 prefixlen 64 scopeid
> 0x10
> inet 10.117.1.130 netmask 0xfffffff8 broadcast 10.117.1.135
> pfsync0: flags=41<UP,RUNNING> mtu 1500
> priority: 0
> pfsync: syncdev: vlan995 maxupd: 255 defer: off
> groups: carp pfsync
>
> As you see in next tcpdump capture, there is some discussions between
> the two routers:
>
> # tcpdump -nni vlan995
> tcpdump: listening on vlan995, link-type EN10MB
> tcpdump: WARNING: compensating for unaligned libpcap packets
> 23:41:13.699617 10.117.1.130: PFSYNCv6 len 108
> act UPD ST COMP count 1
> ...
> (DF) [tos 0x10]
> 23:41:14.158500 10.117.1.129: PFSYNCv6 len 108
> act UPD ST COMP count 1
> ...
> (DF) [tos 0x10]
> 23:41:14.941396 SSTP STP config root=83e3.0:a:b8:7b:27:80 rootcost=3
> bridge=c3e3.0:17:e:2e:f:80 port=142 ifcost=130 age=1/0 max=20/0
> hello=2/0 fwdelay=15/0 pvid=995
> 23:41:14.949617 10.117.1.130: PFSYNCv6 len 108
> act UPD ST COMP count 1
> ...
> (DF) [tos 0x10]
> 23:41:15.237655 10.117.1.129: PFSYNCv6 len 640
> act UPD ST COMP count 1
> ...
> (DF) [tos 0x10]
> 23:41:15.949617 10.117.1.130: PFSYNCv6 len 124
> act UPD ST COMP count 1
> ...
> (DF) [tos 0x10]
> 23:41:16.255230 10.117.1.129: PFSYNCv6 len 36
> act DEL ST COMP count 1
> id: 51d16a3500006c33 creatorid: a10bbd21
> (DF) [tos 0x10]
> 23:41:16.946454 SSTP STP config root=83e3.0:a:b8:7b:27:80 rootcost=3
> bridge=c3e3.0:17:e:2e:f:80 port=142 ifcost=130 age=1/0 max=20/0
> hello=2/0 fwdelay=15/0 pvid=995
> 23:41:16.949619 10.117.1.130: PFSYNCv6 len 1116
> act UPD ST COMP count 13
> ...
> (DF) [tos 0x10]
>
>
> The problem is simple, when i initiate a stateful connection from one
> server, the return (by second router) is blocked by PF (i see the return
> with pflog0)
>
> To be precise here is an example (and tested path):
>
> OBSD NTP -> OBSD router 1 -> WAN...ftp.fr.openbsd.org...WAN -> OBSD
> router 2 || blocked
>
> PF allow in/out routing traffic from this server but incoming from WAN
> is blocked by default
>
> Can you confirm to me that pfsync may add a state for outgoing tcp
> connection in the second router when the first router add it ?
> Have you got any idea on this issue ?
>
> --
> Best regards,
> Loïc BLOT,
> UNIX systems, security and network expert
> http://www.unix-experience.fr
>
> [demime 1.01d removed an attachment of type application/pgp-signature which
> had a name of signature.asc]
