This repository includes my notes on enabling a true bridge mode setup with AT&T U-Verse and pfSense. I've tested and confirmed this setup with the ARRIS NVG589 and BGW210-700. There are a few other methods to accomplish this, so be sure to see what easiest for you. True Bridge Mode is also possible in a Linux via ebtables or using hardware with a VLAN swap trick. I did not have a Linux router and the VLAN swap did not seem to work for me.
While many residential gateways offer something called _IP Passthrough_, it does not provide the same advantages of a true bridge mode. For example, the NAT table is still managed by the gateway, which is limited to a measily 8192 sessions (although it becomes unstable at even 60% capacity).
This method will allow you to fully utilize your own router and finally solve that pesky NAT table limit.
# Quick Setup
## Prerequisites
* You need at least __three__ network interfaces on your pfSense server.
* The MAC address of your Residential Gateway
* Local or console access to pfSense
* pfSense 2.4.3 _(confirmed working, other versions should work but YMMV)_
If you don't have three NICs, you can buy this cheap USB NIC one [from Amazon](TODO). I've confirmed it works in my setup. It is compatible with FreeBSD 11.1 and I didn't have to install anything to get it working. Also, don't worry about the poor performance of USB NICs. This third NIC will only send/recieve a few packets periodicaly to authenticate your Router Gateway. The rest of your traffic will utilize your other (and much faster) NICs.
1. Edit the following configuration variables in `bin/pfatt.sh` as noted below. `$RG_ETHER_ADDR` should match the MAC address of your Residential Gateway. AT&T will only grant a DHCP lease to the MAC they assigned your device. In my environment, it's:
1. pfSense will detect new interfaces on bootup. Follow the prompts on the console to configure `ngeth0` as your pfSense WAN. Your LAN interface should not change.
If every thing is setup correctly, netgraph should be bridging EAP traffic between the ONT and RG, and tagging the WAN traffic with VLAN0.
# Troubleshoot
## tcpdump
You should run tcpdumps on the `$ONT_IF` interface and the `$RG_IF` interface:
```
tcpdump -ei $ONT_IF
tcpdump -ei $RG_IF
```
From the `$RG_IF` interface, you should see some EAPOL starts like this:
```
MAC (oui Unknown) > MAC (oui Unknown), ethertype EAPOL (0x888e), length 60: POL start
```
These packets come every so often. I think the RG does some backoff / delay if doesn't immediately auth correctly. You can always reboot your RG to initiate the authentication.
If your netgraph is setup correctly, the EAP start packet from the `$RG_IF` will be bridged onto your `$ONT_IF` interface. Then you should see some more EAP packets from the `$ONT_IF` interface and `$RG_IF` interface as they negotiate 802.1/X EAP authentication.
Once that completes, you should start seeing 802.1Q (tagged as vlan0) traffic on your `$ONT_IF ` interface.
Then, you can start another tcpdump on the `vlan0` interface to see if netgraph is bridging over the VLAN0 traffic to `ngeth0`:
```
tcpdump -ei ngeth0
```
If you don't see traffic being bridged between `ngeth0` and `$ONT_IF`, then netgraph is not setup correctly.
If the VLAN0 traffic is being properly handled, next pfSense will need to request an IP. `ngeth0` needs to DHCP using the authorized MAC address. You should see an untagged DCHP request on `ngeth0` carry over to the `$ONT_IF` interface tagged as VLAN0. Then you should get a DHCP response and you're in business.
## Promiscuous Mode
I had to put my `$RG_IF` in promiscuous mode with `/sbin/ifconfig $RG_IF promisc`. Otherwise, the EAP packets would not bridge. I'm not sure if this is due to my USB NIC or a requirement for everyone.
The netgraph system provides a uniform and modular system for the implementation of kernel objects which perform various networking functions. If you're unfamilar with netgraph, this [tutorial](http://www.netbsd.org/gallery/presentations/ast/2012_AsiaBSDCon/Tutorial_NETGRAPH.pdf) is a great introduction.
In this setup, the `ue0` interface is my `$RG_IF` and the `bce0` interface is my `$ONT_IF`. You can generate your own graphviz via `ngctl dot`. Copy the output and paste it at [webgraphviz.com](http://www.webgraphviz.com/).
2. Issue `ngctl list` to list netgraph nodes. Inspect `pfatt.sh` to verify the netgraph output matches the configuration in the script. It should look similar to this:
```
$ ngctl list
There are 9 total nodes:
Name: o2m Type: one2many ID: 000000a0 Num hooks: 3
Name: vlan0 Type: vlan ID: 000000a3 Num hooks: 2
Name: ngeth0 Type: eiface ID: 000000a6 Num hooks: 1
Name: <unnamed> Type: socket ID: 00000006 Num hooks: 0
Name: ngctl28740 Type: socket ID: 000000ca Num hooks: 0
Name: waneapfilter Type: etf ID: 000000aa Num hooks: 2
Name: laneapfilter Type: etf ID: 000000ae Num hooks: 3
Name: bce0 Type: ether ID: 0000006e Num hooks: 1
Name: ue0 Type: ether ID: 00000016 Num hooks: 2
```
3. Inspect the node and hooks. Example for `ue0`:
```
$ ngctl show ue0:
Name: ue0 Type: ether ID: 00000016 Num hooks: 2
Local hook Peer name Peer type Peer ID Peer hook
---------- --------- --------- ------- ---------
upper laneapfilter etf 000000ae nomatch
lower laneapfilter etf 000000ae downstream
```
### Reset netgraph
`pfatt.sh` expects a clean netgraph before it can be ran. To reset a broken netgraph state, try this:
In some circumstances, pfSense may alter your netgraph. This is especially true if pfSense manages either your `$RG_IF` or `$ONT_IF`. If you make some interface changes and your connection breaks, check to see if your netgraph was changed.
This setup has been tested on physical servers and virtual machines. Virtualization adds another layer of complexity for this setup, and will take extra consideration.
## QEMU / KVM / Proxmox
Proxmox uses a bridged networking model, and thus utilizes Linux's native bridge capability. Unfortunately due to the two types of traffic we are bridging (EAP/802.1X and VLAN0/802.1Q), I could never get the traffic to forward through the Linux bridge to the virtual interface of my pfSense VM. Instead, I had to utilize PCI passthrough for my `$RG_IF` and `$ONT_IF` NICs.
I believe EAP/802.1X just requires setting the `group_fwd_mask`, but I'm not sure how to get the VLAN0/802.1Q traffic to bridge. If you know why, please open an issue!
Alternatively, you can also do the EAP / VLAN0 magic at the Linux hypervisor layer. Apply the Linux method, then bridge the Linux vlan0 interface to your pfSense VM.
## ESXi
I haven't tried to do this with ESXi. Feel free to submit a PR with notes on your experience.
# Other Methods
## Linux
If you're looking how to do this on a Linux-based router, please refer to [this method](http://blog.0xpebbles.org/Bypassing-At-t-U-verse-hardware-NAT-table-limits) which utilizes ebtables and some kernel features. The method is well-documented there and I won't try to duplicate it. This method is generally more straight forward than doing this on BSD. However, please submit a PR for any additional notes for running on Linux routers.
## VLAN Swap
There is a whole thread on this at [DSLreports](http://www.dslreports.com/forum/r29903721-AT-T-Residential-Gateway-Bypass-True-bridge-mode). The gist of this method is that you connect your ONT, RG and WAN to a switch. Create two VLANs. Assign the ONT and RG to VLAN1 and the WAN to VLAN2. Let the RG authenticate, then change the ONT VLAN to VLAN2. The WAN the DHCPs and your in business.
However, I don't think this works for everyone. I had to explicity tag my WAN traffic to VLAN0 which wasn't supported on my switch.
I haven't tried this with OPNSense or native FreeBSD, but I imagine the process is the same with netgraph. Feel free to submit a PR with notes on your experience.
This took a lot of testing and a lot of hours to figure out. A unique solution was required for this to work in pfSense. If this helped you out, please buy us a coffee.
