---
name: "ql2tpd.toml"
section: "5"
platform: "linux"
package: "go-l2tp"
version: "0.1.8-1+b10"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/ql2tpd.toml"
---

# ql2tpd.toml(5)

configuration file for ql2tpd

## NAME

**ql2tpd.toml** - configuration file for **ql2tpd**

## DESCRIPTION

The **ql2tpd.toml** file configures **ql2tpd**. It calls out the L2TP tunnels and sessions to establish.

**ql2tpd.toml** is written in the TOML markup langange (https://toml.io/en/).

Tunnel and session instances are called out in the configuration file using named TOML tables.

Each tunnel or session instance table contains configuration parameters for that instance as key:value pairs.

Each tunnel and session has a minimal set of configuration which ***must*** be specified.

In addition, each tunnel or session entry may call out various optional key:value pairs which will control **ql2tpd**’s runtime behaviour.

These options are generally not required, and **ql2tpd** will use sensible defaults for them if they are not included in the configuration.

### TUNNEL CONFIGURATION

Tunnels are described using named entries in the \`tunnel' table.

Each tunnel entry describes a single tunnel instance, and must call out at least:

- •

  the tunnel L2TP version (only L2TPv3 is supported),

- •

  the tunnels encapsulation protocol,

- •

  the local IP address,

- •

  the local tunnel ID,

- •

  the peer’s IP address,

- •

  the peer’s tunnel ID.

Here is the full list of tunnel configuration options:

-

  ```
  # This is a tunnel instance named "t1"
  [tunnel.t1]
  # version specifies the version of the L2TP specification the
  # tunnel should use.
  # Only "l2tpv3" is supported.
  version = "l2tpv3"
  # encap specifies the encapsulation to be used for the tunnel.
  # L2TPv3 tunnels may be UDP or IP.
  encap = "udp"
  # local specifies the local address that the tunnel should
  # bind its socket to
  local = "127.0.0.1:5000"
  # tid specifies the local tunnel ID of the tunnel.
  # Tunnel IDs must be unique for the host.
  # L2TPv2 tunnel IDs are 16 bit, and may be in the range 1 - 65535.
  # L2TPv3 tunnel IDs are 32 bit, and may be in the range 1 - 4294967295.
  tid = 62719
  # peer specifies the address of the peer that the tunnel should
  # connect its socket to
  peer = "127.0.0.1:5001"
  # ptid specifies the peer's tunnel ID for the tunnel.
  # The peer's tunnel ID must be unique for the peer, and are unrelated
  # to the local tunnel ID.
  # The rules for tunnel ID range apply to the peer tunnel ID too.
  ptid = 72819
  # hello_timeout if set enables L2TP keep-alive (HELLO) messages.
  # A hello message is sent N milliseconds after the last control
  # message was sent or received.  It allows for early detection of
  # tunnel failure on quiet connections.
  # By default no keep-alive messages are sent.
  hello_timeout = 7500 # milliseconds
  ```

### SESSION CONFIGURATION

Sessions are described using named entries in the \`session' table inside the parent tunnel table.

Each session entry describes a single session instance within the parent tunnel, and must call out at least:

- •

  the pseudowire type to be used (this must be Ethernet),

- •

  the local session ID,

- •

  the peer’s session ID

Here is the full list of session configuration options:

-

  ```
  # This is a session instance called "s1" within parent tunnel "t1".
  # Session instances are always created inside a parent tunnel.
  [tunnel.t1.session.s1]
  # pseudowire specifies the type of layer 2 frames carried by the session.
  # Static sessions support Ethernet pseudowires only.
  pseudowire = "eth"
  # sid specifies the local session ID of the session.
  # Session IDs must be unique to the tunnel for L2TPv2, or unique to
  # the peer for L2TPv3.
  # L2TPv2 session IDs are 16 bit, and may be in the range 1 - 65535.
  # L2TPv3 session IDs are 32 bit, and may be in the range 1 - 4294967295.
  sid = 12389
  # psid specifies the peer's session ID for the session.
  # The peer's session ID is unrelated to the local session ID.
  # The rules for the session ID range apply to the peer session ID too.
  psid = 1234
  # seqnum, if set, enables the transmission of sequence numbers with
  # L2TP data messages.  Use of sequence numbers enables the data plane
  # to reorder data packets to ensure they are delivered in sequence.
  # By default sequence numbers are not used.
  seqnum = false
  # cookie, if set, specifies the local L2TPv3 cookie for the session.
  # Cookies are a data verification mechanism intended to allow misdirected
  # data packets to be detected and rejected.
  # Transmitted data packets will include the local cookie in their header.
  # Cookies may be either 4 or 8 bytes long, and contain aribrary data.
  # By default no local cookie is set.
  cookie = [ 0x12, 0xe9, 0x54, 0x0f, 0xe2, 0x68, 0x72, 0xbc ]
  # peer_cookie, if set, specifies the L2TPv3 cookie the peer will send in
  # the header of its data messages.
  # Messages received without the peer's cookie (or with the wrong cookie)
  # will be rejected.
  # By default no peer cookie is set.
  peer_cookie = [ 0x74, 0x2e, 0x28, 0xa8 ]
  # interface_name, if set, specifies the network interface name to be
  # used for the session instance.
  # By default the Linux kernel autogenerates an interface name specific to
  # the pseudowire type, e.g. "l2tpeth0", "ppp0".
  # Setting the interface name can be useful when you need to be certain
  # of the interface name a given session will use.
  # By default the kernel autogenerates an interface name.
  interface_name = "l2tpeth42"
  # l2spec_type specifies the L2TPv3 Layer 2 specific sublayer field to
  # be used in data packet headers as per RFC3931 section 3.2.2.
  # Currently supported values are "none" and "default".
  # By default no Layer 2 specific sublayer is used.
  l2spec_type = "default"
  ```

## SEE ALSO

**ql2tpd**(1)

## AUTHORS

Katalix Systems, Ltd.