path: root/docs/configuration/interfaces/pppoe.md

---
lastproofread: '2026-03-03'
---

(pppoe-interface)=

# PPPoE

{abbr}`PPPoE (Point-to-Point Protocol over Ethernet)` is a network protocol
that encapsulates PPP frames within Ethernet frames.
It's often used for connecting ISP clients to a broadband access server.

## Configuration

### Common interface configuration

```{cmdincludemd} /_include/interface-description.txt
:var0: pppoe
:var1: pppoe0
```

```{cmdincludemd} /_include/interface-disable.txt
:var0: pppoe
:var1: pppoe0
```

```{cmdincludemd} /_include/interface-mtu.txt
:var0: pppoe
:var1: pppoe0
```

```{cmdincludemd} /_include/interface-vrf.txt
:var0: pppoe
:var1: pppoe0
```


### PPPoE options

```{cfgcmd} set interfaces pppoe \<interface\> access-concentrator \<name\>

**Configure the name of the target access concentrator for the PPPoE session.**

During the PPPoE discovery process, the client sends a PPPoE initiation packet.
Multiple access concentrators may respond with offer packets, and the client
selects one of them.

This setting restricts the client to establishing sessions only with the
specified access concentrator.
```

```{cfgcmd} set interfaces pppoe \<interface\> authentication username \<username\>

**Configure the username for PPPoE session authentication.**

Although authentication is optional in the interface configuration, most ISPs
require it to establish a connection.
```

```{cfgcmd} set interfaces pppoe \<interface\> authentication password \<password\>

**Configure the password for PPPoE session authentication.**

Although authentication is optional in the interface configuration, most ISPs
require it to establish a connection.
```

```{cfgcmd} set interfaces pppoe \<interface\> connect-on-demand

**Enable dial-on-demand on the PPPoE interface.**

When enabled, the system establishes a PPPoE connection only when traffic
passes through the interface. If the connection fails, it is reestablished when
traffic resumes.

For on-demand connections, you must also configure an ``idle-timeout`` period
to disconnect the session after inactivity.

:::{note}
Setting the idle timeout to zero, or leaving it unconfigured, keeps
the connection active continuously once established.
:::

By default, the PPPoE connection is established at boot and remains active
continuously; if the connection fails, it is reestablished immediately.
```

```{cfgcmd} set interfaces pppoe \<interface\> no-default-route

Request an IP address from the PPPoE server without installing a default route.

Example:

:::{code-block} none
set interfaces pppoe pppoe0 no-default-route
:::

:::{note}
Introduced in VyOS 1.4, this command inverts the logic of the former
``default-route`` CLI option.
:::
```

```{cfgcmd} set interfaces pppoe \<interface\> default-route-distance \<distance\>

Configure the distance for the default gateway provided by the PPPoE server.

Example:

:::{code-block} none
set interfaces pppoe pppoe0 default-route-distance 220
:::
```

```{cfgcmd} set interfaces pppoe \<interface\> mru \<mru\>

**Configure the** {abbr}`MRU (Maximum Receive Unit)` **for the PPPoE
interface.**

This setting instructs the pppd daemon to restrict the remote peer from sending
packets larger than the configured MRU. Allowed MRU values range from 128 to
16384 bytes.

An MRU of 296 is suitable for very slow links (40 bytes for the TCP/IP header
and 256 bytes for data).

The default MRU is 1492 bytes.

:::{note}
When using the IPv6 protocol, the MRU must be at least 1280 bytes.
:::
```

```{cfgcmd} set interfaces pppoe \<interface\> idle-timeout \<time\>

**Configure the idle timeout for on-demand PPPoE sessions.**

This setting defines how long the connection remains active without any traffic
before being disconnected.

:::{note}
Setting the idle timeout to zero, or leaving it unconfigured, keeps
the connection active continuously once established.
:::
```

```{cfgcmd} set interfaces pppoe \<interface\> holdoff \<time\>

**Configure the redial delay for persistent PPPoE sessions.**

If a persistent session (with ``connect-on-demand`` disabled) is terminated by
the remote peer or drops unexpectedly, the router waits the specified interval
before attempting to reconnect.

The default redial delay is 30 seconds.
```

```{cfgcmd} set interfaces pppoe \<interface\> local-address \<address\>

**Configure the local endpoint IP address for PPPoE sessions.**

By default, this IP address is negotiated.
```

```{cfgcmd} set interfaces pppoe \<interface\> no-peer-dns

Disable the installation of advertised DNS nameservers on the local system.
```

```{cfgcmd} set interfaces pppoe \<interface\> remote-address \<address\>

**Configure the remote endpoint IP address for PPPoE sessions.**

By default, this IP address is negotiated.
```

```{cfgcmd} set interfaces pppoe \<interface\> service-name \<name\>

**Configure the service name of the target access concentrator for the PPPoE
session.**

By default, the PPPoE interface connects to any available access concentrator.
```

```{cfgcmd} set interfaces pppoe \<interface\> source-interface \<source-interface\>

**Configure the underlying interface for the PPPoE connection.**

Each PPPoE connection is established over an underlying interface, which can be
an Ethernet interface, a VIF, or a bonding interface.
```

```{cfgcmd} set interfaces pppoe \<interface\> ip adjust-mss \<mss | clamp-mss-to-pmtu\>

**Configure the** {abbr}`MSS (Maximum Segment Size)` **advertised in outgoing
TCP SYN packets on the specified interface.**

By clamping the MSS value in TCP SYN packets, you instruct the remote side not
to send packets larger than the specified size. This helps prevent connection
issues if {abbr}`PMTUD (Path MTU Discovery)` fails.

The following options are available:

* ``mss``: Sets the MSS to a specific value in bytes.
* ``clamp-mss-to-pmtu``: Sets the MSS to the interface’s MTU minus 40 bytes for
  IPv4 traffic (20 bytes for the IPv4 header and 20 bytes for the TCP header).
  This option is recommended to automatically set the proper value.

:::{note}
Introduced in VyOS 1.4, this command replaces the older ``set firewall
options interface <name> adjust-mss <value>`` syntax.
:::
```

```{cfgcmd} set interfaces pppoe \<interface\> ip disable-forwarding

**Configure the interface for host or router behavior.**

If configured, the interface switches to host mode, and IPv4 forwarding is
disabled on it.
```

```{cfgcmd} set interfaces pppoe \<interface\> ip source-validation \<strict | loose | disable\>

**Configure source IP address validation using**
{abbr}`RPF (Reverse Path Forwarding)` **on this interface, as specified in**
{rfc}`3704`.

The following options are available:

* ``strict``: Each incoming packet’s source IP address is checked against the
  {abbr}`FIB (Forwarding Information Base)`. If the interface is not the best
  route back to that source, validation fails, and the packet is dropped.
* ``loose``: Each incoming packet’s source IP address is checked against the
  {abbr}`FIB (Forwarding Information Base)`. If the source IP address is
  unreachable through any interface, validation fails.
* ``disable``: No source IP address validation is performed. All incoming
  packets are accepted.

{rfc}`3704` recommends enabling ``strict`` mode to prevent IP spoofing, such as
DDoS attacks. For asymmetric or other complex routing scenarios, use ``loose``
mode.
```


#### IPv6

```{cfgcmd} set interfaces pppoe \<interface\> ipv6 address autoconf

Enable IPv6 address assignment via {abbr}`SLAAC (Stateless Address
Auto-Configuration)` on this interface.
```

```{cfgcmd} set interfaces pppoe \<interface\> ipv6 adjust-mss \<mss | clamp-mss-to-pmtu\>

**Configure the** {abbr}`MSS (Maximum Segment Size)` **advertised in outgoing
TCP SYN packets on the specified interface.**

By clamping the MSS value in TCP SYN packets, you instruct the remote side not
to send packets larger than the specified size. This helps prevent connection
issues if {abbr}`PMTUD (Path MTU Discovery)` fails.

The following options are available:

* ``mss``: Sets the MSS to a specific value in bytes.
* ``clamp-mss-to-pmtu``: Sets the MSS to the interface’s MTU minus 60 bytes for
  IPv6 traffic (40 bytes for the IPv6 header and 20 bytes for the TCP header).
  This option is recommended to automatically set the proper value.

:::{note}
Introduced in VyOS 1.4, this command replaces the older ``set firewall
options interface <name> adjust-mss <value>`` syntax.
:::
```

```{cfgcmd} set interfaces pppoe \<interface\> ipv6 disable-forwarding

**Configure the interface for host or router behavior.**

If configured, the interface switches to host mode, and IPv6 forwarding is
disabled on it.
```

```{cmdincludemd} /_include/interface-dhcpv6-prefix-delegation.txt
:var0: pppoe
:var1: pppoe0
```


## Operation

```{opcmd} show interfaces pppoe \<interface\>

Show detailed information about a specific PPPoE interface.

:::{code-block} none
vyos@vyos:~$ show interfaces pppoe pppoe0
pppoe0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1492 qdisc pfifo_fast state UNKNOWN group default qlen 3
    link/ppp
    inet 192.0.2.1 peer 192.0.2.255/32 scope global pppoe0
       valid_lft forever preferred_lft forever

    RX:  bytes    packets     errors    dropped    overrun      mcast
    7002658233    5064967          0          0          0          0
    TX:  bytes    packets     errors    dropped    carrier collisions
     533822843    1620173          0          0          0          0
:::
```

```{opcmd} show interfaces pppoe \<interface\> queue

Show queue information for a specific PPPoE interface.

:::{code-block} none
vyos@vyos:~$ show interfaces pppoe pppoe0 queue
qdisc pfifo_fast 0: root refcnt 2 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
 Sent 534625359 bytes 1626761 pkt (dropped 62, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
:::
```


### Connect/disconnect

```{opcmd} disconnect interface \<interface\>

Disconnect the specified interface.
```

```{opcmd} connect interface \<interface\>

Initiate a session on the specified interface.
```


## Example

### PPPoE over DSL

**Configuration scenario:**

- Your ISP's DSL modem is connected to the `eth0` interface on your VyOS
  router.
- Your ISP does not require VLAN tagging.
- PPPoE credentials are provided by your ISP. The typical username format is
  `name@host.net`, though this may vary.

**Configuration notes:**

- The maximum MTU size for DSL is 1492 because of PPPoE overhead. If you are
  switching from a DHCP-based ISP (e.g., a standard cable connection), ensure
  VPN links have MTU sizes adjusted accordingly.
- To ignore ISP-provided nameservers and use only your statically configured
  ones, set the `name-server` option to `none`.
- A default route is automatically installed once the interface is up. To
  change this behavior, use the `no-default-route` CLI option.

:::{note}
The PPPoE configuration syntax changed after VyOS 1.2 (Crux) and is
automatically migrated during an upgrade.
:::

```none
set interfaces pppoe pppoe0 authentication username 'userid'
set interfaces pppoe pppoe0 authentication password 'secret'
set interfaces pppoe pppoe0 source-interface 'eth0'
```

Secure your setup by creating rules matching the `pppoe0` interface in the
firewall chains:

```none
set firewall ipv4 input filter rule 10 inbound-interface name 'pppoe0'
set firewall ipv4 forward filter rule 10 inbound-interface name 'pppoe0'
```


### PPPoE over VLAN

Some ISPs require PPPoE connections to be
established over a VLAN interface. This specific topology is fully supported by
VyOS.

The following configuration establishes the PPPoE connection through VLAN 7,
which is the default VLAN for Deutsche Telekom:

```none
set interfaces pppoe pppoe0 authentication username 'userid'
set interfaces pppoe pppoe0 authentication password 'secret'
set interfaces pppoe pppoe0 source-interface 'eth0.7'
```


#### IPv6 DHCPv6 prefix delegation

**Configuration scenario:**

The following configuration establishes a PPPoE session on the `eth1`
interface, requests a `/56` IPv6 prefix delegation from the ISP, and assigns
a `/64` subnet from that delegation to the `eth0` interface.

**Configuration notes:**

- The IPv6 address assigned to `eth0` is `<prefix>::1/64`.
- If you do not know your delegated prefix size, begin with `sla-len 0`.
- To advertise the prefix on the `eth0` link, configure IPv6 Router
  Advertisement.

```none
set interfaces pppoe pppoe0 authentication username vyos
set interfaces pppoe pppoe0 authentication password vyos
set interfaces pppoe pppoe0 dhcpv6-options pd 0 interface eth0 address '1'
set interfaces pppoe pppoe0 dhcpv6-options pd 0 interface eth0 sla-id '0'
set interfaces pppoe pppoe0 dhcpv6-options pd 0 length '56'
set interfaces pppoe pppoe0 ipv6 address autoconf
set interfaces pppoe pppoe0 source-interface eth1

set service router-advert interface eth0 prefix ::/64
```