PPPoE

PPPoE is a network protocol for encapsulating PPP frames inside Ethernet frames. It appeared in 1999, in the context of the boom of DSL as the solution for tunneling packets over the DSL connection to the ISPs IP network, and from there to the rest of the Internet. A 2005 networking book noted that “Most DSL providers use PPPoE, which provides authentication, encryption, and compression.” Typical use of PPPoE involves leveraging the PPP facilities for authenticating the user with a username and password, predominately via the PAP protocol and less often via CHAP.

Operating Modes

VyOS supports setting up PPPoE in two different ways to a PPPoE internet connection. This is due to most ISPs provide a modem that is also a wireless router.

Home Users

In this method, the DSL Modem/Router connects to the ISP for you with your credentials preprogrammed into the device. This gives you an RFC 1918 address, such as 192.168.1.0/24 by default.

For a simple home network using just the ISP’s equipment, this is usually desirable. But if you want to run VyOS as your firewall and router, this will result in having a double NAT and firewall setup. This results in a few extra layers of complexity, particularly if you use some NAT or tunnel features.

Business Users

In order to have full control and make use of multiple static public IP addresses, your VyOS will have to initiate the PPPoE connection and control it. In order for this method to work, you will have to figure out how to make your DSL Modem/Router switch into a Bridged Mode so it only acts as a DSL Transceiver device to connect between the Ethernet link of your VyOS and the phone cable. Once your DSL Transceiver is in Bridge Mode, you should get no IP address from it. Please make sure you connect to the Ethernet Port 1 if your DSL Transeiver has a switch, as some of them only work this way.

Once you have an Ethernet device connected, i.e. eth0, then you can configure it to open the PPPoE session for you and your DSL Transceiver (Modem/Router) just acts to translate your messages in a way that vDSL/aDSL understands.

Configuration Example

Requirements:

  • Your ISPs modem is connected to port eth0 of your VyOS box.
  • No VLAN tagging required by your ISP.
  • You need your PPPoE credentials from your DSL ISP in order to configure this. The usual username is in the form of name@host.net but may vary depending on ISP.
  • The largest MTU size you can use with DSL is 1492 due to PPPoE overhead. If you are switching from a DHCP based ISP like cable then be aware that things like VPN links may need to have their MTU sizes adjusted to work within this limit.
  • With the default-route option set to auto, VyOS will only add the default gateway you receive from your DSL ISP to the routing table if you have no other WAN connections. If you wish to use a dual WAN connection, change the default-route option to force.
  • With the name-server option set to none, VyOS will ignore the nameservers your ISP sens you and thus you can fully rely on the ones you have configured statically.
set interfaces ethernet eth0 description "DSL Modem"
set interfaces ethernet eth0 duplex auto
set interfaces ethernet eth0 smp_affinity auto
set interfaces ethernet eth0 speed auto
set interfaces ethernet eth0 pppoe 0 default-route 'auto'
set interfaces ethernet eth0 pppoe 0 mtu 1492
set interfaces ethernet eth0 pppoe 0 name-server 'auto'
set interfaces ethernet eth0 pppoe 0 user-id 'userid'
set interfaces ethernet eth0 pppoe 0 password 'secret'

You should add a firewall to your configuration above as well by assigning it to the pppoe0 itself as shown here:

set interfaces ethernet eth0 pppoe 0 firewall in name NET-IN
set interfaces ethernet eth0 pppoe 0 firewall local name NET-LOCAL
set interfaces ethernet eth0 pppoe 0 firewall out name NET-OUT
VLAN Example

Some recent ISPs require you to build the PPPoE connection through a VLAN interface. One of those ISPs is e.g. Deutsche Telekom in Germany. VyOS can easily create a PPPoE session through an encapsulated VLAN interface. The following configuration will run your PPPoE connection through VLAN7 which is the default VLAN for Deutsche Telekom:

set interfaces ethernet eth0 description "DSL Modem"
set interfaces ethernet eth0 duplex auto
set interfaces ethernet eth0 smp_affinity auto
set interfaces ethernet eth0 speed auto
set interfaces ethernet eth0 vif 7 pppoe 0 default-route 'auto'
set interfaces ethernet eth0 vif 7 pppoe 0 mtu '1492'
set interfaces ethernet eth0 vif 7 pppoe 0 name-server 'auto'
set interfaces ethernet eth0 vif 7 pppoe 0 user-id 'userid#[email protected]'
set interfaces ethernet eth0 vif 7 pppoe 0 password 'secret'

Troubleshooting

disconnect interface <interface>

Test disconnecting given connection-oriented interface. <interface> can be pppoe0 as example.

connect interface <interface>

Test connecting given connection-oriented interface. <interface> can be pppoe0 as example.

show interfaces pppoe <interface>

Check PPPoE connection logs with the following command which shows the current statistics, status and some of the settings (i.e. MTU) for the current connection on <interface> (e.g. pppoe0)

show interfaces pppoe <interface> log

Show entire log for the PPPoE connection starting with the oldest data. Scroll down with the <space> key to reach the end where the current data is.

show interfaces pppoe <interface> log tail

Shows the same log as without the ‘tail’ option but start with the last few lines and continues to show added lines until you exit with Ctrl + x