Bridge Interfaces and ARPs
Aleksandr A Babaylov
. at babolo.ru
Fri Dec 4 08:09:22 UTC 2015
On Thu, Dec 03, 2015 at 08:54:10AM -0500, Jason Van Patten wrote:
> Hey gang -
>
> I posted this to the FreeBSD user forums but figured I'd send a message
> off to the list to see if anyone has any input, guidance, or ideas.
> Emailing diagrams around isn't good form (IMHO) but having a diagram
> handy will help with the discussion. So please glance at:
>
> http://pics.lateapex.net/vz.png
>
> Background: I have a business class Verizon FIOS connection for Internet
> at home. Along with that connection, I have 13 (not 14!) static IPs
> from VZ. They almost fall within a proper CIDR block, but not quite:
> 1.2.3.210 - 1.2.3.222. I don't own .209, so I can't claim 1.2.3.208/28
> as my IP block (dammit!) The subnet for the static IPs is a /24, and
> the default route is *Verizon's* router: 1.2.3.1.
>
> There are a number of different choices for this network layout: DMZ,
> bridging, or binat. I chose bridging so that I don't have the
> complexity of binatting, and yet have some protection for the servers
> via my router. So, per the drawing, the FreeBSD router's em0 is
> connected to the Verizon equipment, while re0 and re1 are both connected
> to a managed Cisco switch, on different VLANs.
>
> VLAN 10 for re0: Public IPs (public services, etc)
> VLAN 20 for re1: Private IPs (NAS, wireless AP, etc)
>
> Via the router, VLAN 10 and Verizon's network are bridged together. The
> bridge interface on the router has IP: 1.2.3.222/24 with a default route
> set to 1.2.3.1. All servers on VLAN 10 have IPs within the allocated
> range (.210 - .220) and the same default route.
>
> Now: the problem. I used the LAGG'd server as an example in the
> diagram, but the same thing is happening with other servers: the router
> is learning ARP entries for the IPs I own *from* Verizon's router. As
> soon as the router caches that bad entry, it no longer routes traffic to
> those public IPs *from* VLAN 20 (private side). So, in other words, a
> laptop on the wireless network won't be able to get to 1.2.3.215.
>
> My work-around for now has been a series of static ARP entries on the
> router for each of my public servers. That seems to work fine, but I
> wonder if there's something I might be doing wrong?
>
> If I didn't include enough info, fire away. Thanks!
May be it is proxy arp from Verison.
Just delete bridge0
ifconfig em0 inet 1.2.3.222/24
ifconfig re0 inet 127.127.127.127/24 or any other fake net
route add 1.2.3.210/31 -iface re0
route add 1.2.3.212/30 -iface re0
route add 1.2.3.216/30 -iface re0
route add 1.2.3.220/31 -iface re0
sysctl net.link.ether.inet.proxyall=1
Default router for your public servers 1.2.3.222
in /28 or wider net.
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