Using an OpenBSD Router with AT&T U-Verse
I upgraded to AT&T's U-verse Gigabit internet service in 2017 and it came with an Arris BGW-210 as the WiFi AP and router. The BGW-210 is not a terrible device, but I already had my own Airport Extreme APs wired throughout my house and an OpenBSD router configured with various things, so I had no use for this device. It's also a potentially-insecure device that I can't upgrade or fully disable remote control over.
Fully removing the BGW-210 is not possible as we'll see later, but it is possible to remove it from the routing path. This is how I did it with OpenBSD.
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When the service was originally installed by AT&T, a fiber-optic cable terminated at an ONT in my basement, which then connected to the BGW-210 via ethernet.
I tried swapping my OpenBSD router in place of the BGW-210 but it could not get a DHCP lease or receive any traffic from the ONT, despite a properly negotiated ethernet connection.
After capturing some network traffic between the ONT and the BGW-210, I learned that the BGW-210 does 802.1X EAP authentication with a certificate installed on the device and all traffic is encapsulated in an 802.1Q VLAN (with a VLAN id of zero). Until this negotiation is performed, the upstream device will not respond.
The EAP certificate on the BGW-210 cannot easily be exported, making it difficult to easily use a third-party router with AT&T's service (Hush-A-Phone, anyone?). However, since the EAP authentication is only done at the beginning of the connection, it is possible to just proxy those authentication packets between the BGW-210 and AT&T to authenticate the connection and then use a 3rd party router for all DHCP and routing afterwards.
I'm not the first person to want to use their own router on AT&T's U-verse
service, so there are already
solutions out there for proxying EAP.
I went with
since it was small and written in Go, and only needed minor changes to support
OpenBSD which the author has since merged.
eap_parrot can be installed with
go get (
jcs@pf:~> mkdir go; cd go jcs@pf:~/go> go get github.com/mjonuschat/eap_parrot jcs@pf:~/go> sudo install -m 755 -o root -g wheel bin/eap_parrot /usr/local/bin/eap_parrot
Then it just needs a small configuration file:
jcs@pf:~> cat /etc/eap_parrot.toml [network] wan_interface="em0" router_interface="em2" vlan_id=-1 promiscuous_mode=false [logging] syslog=true debug=true debug_packets=false [ignore] start=false logoff=false
/etc/rc.d/eap_parrot script can be created and then enabled to run on
rcctl enable eap_parrot):
jcs@pf:~> cat /etc/rc.d/eap_parrot #!/bin/ksh daemon="/usr/local/bin/eap_parrot" daemon_flags="-config /etc/eap_parrot.toml" rc_bg=YES . /etc/rc.d/rc.subr rc_reload=NO rc_cmd $1
After a test run with
eap_parrot, I was able to get an IP from OpenBSD via
I recently upgraded and moved all of my networking and server equipment into a half-rack:
- Cisco SG11016NA 16-port gigabit unmanaged switch
- Supermicro E300-8D server with rackmount kit for firewall/router running OpenBSD
- USRobotics Total Control NETServer 8-modem chassis for my BBS running OpenBSD
- Grandstream HT818 8-port VoIP ATA for the 8 modems
- Mini-ITX BBS server
- Akitio Thunder2 Thunderbolt enclosure with hard disks for storage, connected to the Mac Mini
- Mac Mini that runs Plex, Indigo Domotics for Z-wave automation, and handles Time Machine backups
- Tripp Lite 1500VA UPS
Here's an ASCII diagram of my AT&T U-verse routing setup now:
.-[ 192.168.1.1/24 - gigabit switch for servers, wireless APs ] +-[vlan1]-[ 192.168.2.1/24 - guest WiFi ] | | .-[ 192.168.4.1/24 - BGW-210 LAN port ]---------------. | | | | .---------|-----------------------------------. .-------------|--. `-|-[em1] [em3] [em5] [ix1] Supermicro E-300-8D | | BGW-210 | | .-[vlan0]-|-[em0] [em2] [em4] [ix0] OpenBSD 6.4 - pf | | [uplink] [lan] | | `---------|-----------------------------------' `----|-----------' | | | | `-[ no IP - BGW-210 uplink port ]------------' | | .----------. `-[ public IP (DHCP+DHCPv6) ]---| AT&T ONT |---[ fiber ]---[ AT&T / internet ] `----------'
The uplink port of my OpenBSD router is now
vlan0 which has a parent interface
em0 is configured to clone the MAC address of the BGW-210's
em0 is wired directly to the AT&T ONT, which connects out to the internet.
jcs@pf:~> cat /etc/hostname.em0 up lladdr b0:93:5b:XX:XX:XX descr "ONT" -inet6 jcs@pf:~> cat /etc/hostname.vlan0 parent em0 descr "vlan through ONT" inet6 autoconf
The internal LAN is connected via
em1 and wired into a gigabit switch providing
connectivity to my servers and Airport WiFi APs.
jcs@pf:~> cat /etc/hostname.em1 inet 192.168.1.1 255.255.255.0 192.168.1.255 descr "switch"
vlan1 also rides over
em1 and is used by the Airport APs for its guest WiFi
network (with VLAN id 1003).
jcs@pf:~> cat /etc/hostname.vlan1 inet 192.168.2.1 255.255.255.0 192.168.2.255 parent em1 vnetid 1003 descr "guest wifi"
This enables traffic to be routed to the internet from the guest WiFi network without it being able to reach my normal network.
To quarantine the BGW-210, it is wired directly to a spare port (
em2) on my
OpenBSD router with no IP address.
EAP traffic received from
em2 is proxied through to
no other traffic can pass in or out.
jcs@pf:~> cat /etc/hostname.em2 up descr "at&t router (ONT interface)" -inet6
An ethernet cable is connected from one of the BGW-210's LAN ports to
my OpenBSD router, but the interface is left unconfigured.
In the rare case that I need to access the BGW-210's web interface, I can run
dhclient em3 and get an IP in the
192.168.4.0/24 network from the BGW-210 and
route to it.
AT&T uses DHCPv6 for IPv6 connectivity, so I am using the
pkg_add dhcpcd) for both IPv4 and IPv6 DHCP.
jcs@pf:~> cat /etc/dhcpcd.conf allowinterfaces vlan0 duid slaac hwaddr persistent nooption domain_name_servers, domain_name, domain_search, host_name option interface_mtu # override sending OS version and other crap hostname - vendclass 40712 . # don't run anything at each stage script /usr/bin/true interface vlan0 ia_na 0 ia_pd 1 vlan0/1 em1/2
vendclass 40712 lines were added after doing a
troubleshoot IPv6 and seeing the following in
dhcpcd's DHCPv6 request:
[...] 0040: b093 5bdc b811 0008 0002 006d 0010 004a ..[........m...J 0050: 0000 9f08 0044 6468 6370 6364 2d37 2e30 .....Ddhcpcd-7.0 0060: 2e31 3a4f 7065 6e42 5344 2d36 2e33 3a61 .1:OpenBSD-6.3:a 0070: 6d64 3634 3a49 6e74 656c 2852 2920 5865 md64:Intel(R) Xe 0080: 6f6e 2852 2920 4350 5520 442d 3135 3138 on(R) CPU D-1518 0090: 2040 2032 2e32 3047 487a 000e 0000 0003 @ 2.20GHz...... [...]
I don't know why
dhcpcd sends this information by default, but these values can
be overridden by setting
hostname - and
vendclass 40712 ..
dhcpcd must also be configured to send the same
that the BGW-210 does, which can be found by inspecting the router solicitation
requests from the BGW-210 (shown here from Wireshark):
Frame 46: 167 bytes on wire (1336 bits), 167 bytes captured (1336 bits) Ethernet II, Src: ArrisGro_xx:xx:xx (xx:xx:xx:xx:xx:xx), Dst: IPv6mcast_01:00:02 (33:33:00:01:00:02) 802.1Q Virtual LAN, PRI: 3, DEI: 0, ID: 0 Internet Protocol Version 6, Src: fe80::xxxx:xxxx:xxxx:xxxx, Dst: ff02::1:2 User Datagram Protocol, Src Port: 546, Dst Port: 547 DHCPv6 Message type: Solicit (1) Transaction ID: 0x574b20 Client Identifier Option: Client Identifier (1) Length: 28 Value: 000200000de9xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx... DUID: 000200000de9xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx... DUID Type: assigned by vendor based on Enterprise number (2) Enterprise ID: The Broadband Forum (3561) Identifier: 30303xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Reconfigure Accept Elapsed time Option Request Identity Association for Prefix Delegation
The long string sent as the DUID must be configured in
dhcpcd by writing it
/var/db/dhcpcd/duid file as 28 hexadecimal digits separated by colons:
jcs@pf:~> cat /var/db/dhcpcd/duid 00:02:00:00:0d:e9:[...]
dhcpcd starts up, it will fetch an IPv4 lease through DHCP, then fetch
/60 IPv6 subnet via DHCPv6 and apply the
::1 IP of a
routing to the LAN.
rtadvd enabled (
rcctl enable rtadvd; rcctl set rtadvd flags em1), it will
send out router advertisements to the LAN for clients to autoconfigure themselves