Devices

Besides wired, wireless and VPN interfaces, there are also some other, virtual interfaces, as well as some miscellaneous interface-related. These options can be found under Interfaces ‣ Devices. This document briefly explains these options.

Bridge

Bridging allows to create a connection between separate networks, allow traffic on network A destined for network B (where both networks are connected to your OPNsense device) to reach it via this bridge. Note that this does not include DHCP services—this needs to set using DHCP relaying.

A bridge works like a (layer-2) switch, forwarding traffic from one interface to another. Multicast and broadcast packets are always forwarded to all interfaces that are part of the bridge. For unicast traffic, the bridge learns which MAC addresses are associated with which interfaces and will forward the traffic selectively.

Optionally a bridge can be configured to support (Rapid) Spanning Tree Protocol (RSTP/RTP) to prevent loops in the network topology. These options are provided in the “advanced” section of the configuration and include the following settings:

Option	Description
Enable	Enable the (Rapid) Spanning Tree Protocol
Protocol	Protocol to use, rapid or regular spanning tree
STP interfaces	The interfaces tith [R]STP enabled, from the ones in the bridge
Valid time (maxage)	Set the time that a Spanning Tree Protocol configuration is valid. The default is 20 seconds.
Forward time (fwddelay)	Set the time that must pass before an interface begins forwarding packets when Spanning Tree is enabled. The default is 15 seconds.
Hold count (holdcnt)	Set the transmit hold count for Spanning Tree. This is the number of packets transmitted before being rate limited. The default is 6. The minimum is 1 and the maximum is 10.

Other advanced options available in the bottom section of the screen and include the following settings:

Option	Description
Cache size (maxaddr)	Set the size of the bridge address cache to size. The default is 2000 entries.
Cache entry expire time (timeout)	Set the timeout of address cache entries to this number of seconds. If seconds is zero, then address cache entries will not be expired. The default is 1200 seconds.
Span port	Span ports transmit a copy of every frame received by the bridge. This is most useful for snooping a bridged network passively on another host connected to one of the span ports of the bridge.
Edge ports	Set interface as an edge port. An edge port connects directly to end stations and cannot create bridging loops in the network; this allows it to transition straight to forwarding.
Auto Edge ports	Allow interface to automatically detect edge status. This is the default for all interfaces added to a bridge, selecting interfaces will disable auto mode.
PTP ports	Set the interface as a point-to-point link. This is required for straight transitions to forwarding and should be enabled on a direct link to another RSTP-capable switch.
Auto PTP ports	Automatically detect the point-to-point status on interface by checking the full duplex link status. This is the default for interfaces added to the bridge, selecting interfaces will disable auto mode.
Sticky ports	Mark an interface as a “sticky” interface. Dynamically learned address entries are treated as static once entered into the cache. Sticky entries are never aged out of the cache or replaced, even if the address is seen on a different interface.
Private ports	Mark an interface as a “private” interface. A private interface does not forward any traffic to any other port that is also a private interface.

GIF

GIF (gif(4), Generic Tunnel Interface) can be used to tunnel IPv6 via IPv4 connections. A common use for this is the IPv6 tunnel of Hurricane Electric (he.net).

Note

In IPv6 Tunnel Broker you can find information on how to setup a tunnel using Hurricane Electric

As with all tunnel devices, the most important settings relate to how both ends connect and which addressing will be used to route traffic over the tunnel. The rest of the settings usually are best left to their defaults.

Option	Description
Parent interface	Actually the source address the tunnel will use to connect from.
GIF remote address	Peer address where encapsulated gif packets will be sent.
GIF tunnel local address	The tunnel’s local address which will be configured on the interface.
GIF tunnel remote address	The tunnel’s remote address which will be configured on the interface.
Disable Ingress filtering	Ingress filtering on outer tunnel source can break tunnel operation in an asymmetrically routed networks, in which case this can be disabled by marking this option.
ECN friendly behavior	Note that the ECN friendly behavior violates RFC2893. This should be used in mutual agreement with the peer.
Description	User friendly description for this tunnel

GRE

GRE (gre(4), Generic Routing Encapsulation) is used to create a virtual point-to-point connection, through which encapsulated packages can be sent. This can be used to utilize (OSI-layer 3) protocols between devices over a connection that does not normally support these protocols.

Since the GRE protocol was designed by Cisco, it is often used as default tunnel technology when using their solutions.

A common use-case of GRE is also to forward (no routable) multicast traffic, although this will need additional software such as IGMP-proxy or PIMD, which are less commonly used on OPNsense.

The available settings are similar to those described for the GIF tunnel type:

Option	Description
Parent interface	Actually the source address the tunnel will use to connect from.
GRE remote address	Peer address where encapsulated gif packets will be sent.
GRE tunnel local address	The tunnel’s local address which will be configured on the interface.
GRE tunnel remote address	The tunnel’s remote address which will be configured on the interface.
Description	User friendly description for this tunnel

LAGG

LAGG (lagg(4)) allows for link aggregation, bonding and fault tolerance. This works best if your network switches support. Only unassigned interfaces can be added to LAGG.

The userinterface supports the following options:

Option	Description
Parent interface	Members of the link aggregation
Lag proto	Protocol to use for aggregation, available options are described in the next table. LACP is most commonly used.
Description	User friendly description for this interface
Fast timeout	Enable lacp fast-timeout on the interface.
Use flowid	Use the RSS hash from the network card if available, otherwise a hash is locally calculated. The default depends on the system tunable in net.link.lagg.default_use_flowid.
Hash Layers	Set the packet layers to hash for aggregation protocols which load balance.
Use strict	Enable lacp strict compliance on the interface. The default depends on the system tunable in net.link.lagg.lacp.default_strict_mode.
MTU	MTU size, when unset the smallest mtu of the LAGG children will be used.

Note

Hash Layers, specifies how the device will loadbalance the traffic across physical links in the LAGG bundle. This is done per the 5-tuple if the LACP device implementation allows it. Hash Layers, do not need to be the same between two connecting devices, it can be considered as a best practice but its not a rule of must be.

Available protocols

Name	Description
failover	Sends and receives traffic only through the master port. If the master port becomes unavailable, the next active port is used. The first interface added is the master port; any interfaces added after that are used as failover devices.
fec	Supports Cisco EtherChannel. This is a static setup and does not negotiate aggregation with the peer or exchange frames to monitor the link.
lacp	Supports the IEEE 802.3ad Link Aggregation Control Protocol (LACP) and the Marker Protocol. LACP will negotiate a set of aggregated links with the peer in to one or more Link Aggregated Groups. Each LAG is composed of ports of the same speed, set to full-duplex operation. The traffic will be balanced across the ports in the LAG with the greatest total speed, in most cases there will only be one LAG which contains all ports. In the event of changes in physical connectivity, Link Aggregation will quickly converge to a new configuration.
loadbalance	Balances outgoing traffic across the active ports based on hashed protocol header information and accepts incoming traffic from any active port. This is a static setup and does not negotiate aggregation with the peer or exchange frames to monitor the link. The hash includes the Ethernet source and destination address, and, if available, the VLAN tag, and the IP source and destination address.
roundrobin	Distributes outgoing traffic using a round-robin scheduler through all active ports and accepts incoming traffic from any active port.
none	This protocol is intended to do nothing: It disables any traffic without disabling the lagg interface itself.

Attention

The LAGG protocol should match with the one your switch supports. It is best practice to use LACP if possible. Devices connected via LAGG require the same protocol.

LACP timeout

LACP timeout has two modes; Slow/normal and Fast. It handles how fast the re-convergence occurs in case of link failure. This specifies how often the heartbeats are sent between the two LAGG connected devices.

LACP mode	Heartbeat/Timeout interval	Enable
Slow/Normal	30s	Fast timeout turned off
Fast	1s	Fast timeout turned on

The Slow/normal timeout should be the default in most cases. Due to possible vendor implementation issues, keeping the LACP timeout on Slow/normal is preferable. Fast timeout can cause connectivity disruption in some cases. LACP timeout requires the same value on both devices connected via LAGG. If not, heartbeats can be missed which will cause connectivity disruption.

Read LAGG Setup for an example configuration.

Loopback

Loopbacks are logical virtual interfaces which emulate real interfaces and can be used for different setup scenarios, which require always-on interfaces. Below you will find some scenario’s for which these devices are used.

• Administrative access to services on your machine, which can bind to an address configured on top of the loopback.

• Using loopback addresses as router IDs for OSPF or BGP, which helps to identify your nodes and eases administration

VLAN

VLANs (Virtual LANs) can be used to segment a single physical network into multiple virtual networks. This can be done for QoS purposes, among other things. For this reason, most ISP-issued IPTV devices utilize VLANs.

The following settings are available for these devices:

Name	Description
Device	Device name of this virtual interface, usually starts with vlan or qinq depending on the type
Parent interface	The interface to use as parent which it will send/receive vlan tagged traffic on
VLAN tag	802.1Q VLAN tag (between 1 and 4094)
VLAN priority	802.1Q VLAN PCP (priority code point)
Description	User friendly description for this interface

Note

802.1ad , also known as QinQ, is supported via the VLAN configuration in which case you would stack a vlan on top of a vlan, the device name should start with qinq in that case.

Read VLAN Setup for an example configuration.

VXLAN

Virtual eXtensible Local Area Networks (VXLAN) are used to overlay virtualized layer 2 networks over layer 3 networks as described by rfc7348.

Tunnels can be setup in point to point (parameter Remote address) or multicast (parameters Multicast group and Device). The Source address must be an existing (statically assigned) address assigned at this firewall, which will be used as source in the encapsulating IPv4/IPv6 header.

Note

Since the vxlan interface encapsulates the Ethernet frame with an IP, UDP, and vxlan header, the resulting frame may be larger than the MTU of the physical network. The vxlan specification recommends the physical network MTU be configured to use jumbo frames to accommodate the encapsulated frame size. Alternatively, the MTU size on the vxlan interface might be reduced to allow the encapsulated frame to fit in the current MTU of the physical network.

Read VXLAN Bridge for an example configuration with a common setup.

Point-to-Point

Point-to-Point (PP) interfaces provide direct connectivity between two endpoints without any intermediary devices. These interfaces are commonly used for WAN connections, tunneling, or direct link setups where broadcast and multiple access are not needed.

The following Link Types are available for these interfaces:

PPP (Point-to-Point Protocol)PPPoE (Point-to-Point Protocol over Ethernet)PPTP (Point-to-Point Tunneling Protocol)L2TP (Layer 2 Tunneling Protocol)

A widely used protocol for establishing direct connections over serial links, often utilized for dial-up and DSL connections. Supports authentication (PAP/CHAP), compression, and error detection.

Option	Description
Link interfaces	Select one interface for normal PPP and least two interfaces for Multilink (MLPPP) connections.
Description	You may enter a description here for your reference. Description will appear in the “Interfaces Assign” select lists
Service Provider	Select the country, Provider and Plan for the PPP connection.
Username	Enter your username for CHAP authentication.
Password	Enter your password for CHAP authentication.
Phone Number	Typically *99# for GSM networks and #777 for CDMA networks
Access Point Name (APN)	Enter the APN for your service provider. E.g., internet.t-d1.de for T-Mobile.

Advanced Option	Description
APN number (optional)	Defaults to 1 if you set APN above. Ignored if you set no APN above.
SIM PIN	Enter the SIM PIN if your service provider requires it. Leave blank if not required.
SIM PIN wait	Time to wait for SIM to discover network after PIN is sent to SIM (seconds).
Init String	Enter the modem initialization string here. Do not include the “AT” string at the beginning of the command. Many modern USB 3G modems don’t need an initialization string.
Connection Timeout	Enter timeout in seconds for connection to be established (sec.) Default is 45 sec.
Uptime Logging	This option causes cumulative uptime to be recorded and displayed on the Status Interfaces page.
Dial On Demand	This option causes the interface to operate in dial-on-demand mode. Do not enable if you want your link to be always up. The interface is configured, but the actual connection of the link is delayed until qualifying outgoing traffic is detected.
Idle Timeout	(seconds) Default is 0, which disables the timeout feature. If no incoming or outgoing packets are transmitted for the entered number of seconds the connection is brought down. When the idle timeout occurs, if the dial-on-demand option is enabled, mpd goes back into dial-on-demand mode. Otherwise, the interface is brought down and all associated routes removed.
Compression	This option enables Van Jacobson TCP header compression, which saves several bytes per TCP data packet. You almost always want this option. This compression ineffective for TCP connections with enabled modern extensions like time stamping or SACK, which modify TCP options between sequential packets.
TCPmssFix	This option causes mpd to adjust incoming and outgoing TCP SYN segments so that the requested maximum segment size is not greater than the amount allowed by the interface MTU. This is necessary in many setups to avoid problems caused by routers that drop ICMP Datagram Too Big messages. Without these messages, the originating machine sends data, it passes the rogue router then hits a machine that has an MTU that is not big enough for the data. Because the IP Don’t Fragment option is set, this machine sends an ICMP Datagram Too Big message back to the originator and drops the packet. The rogue router drops the ICMP message and the originator never gets to discover that it must reduce the fragment size or drop the IP Don’t Fragment option from its outgoing data.
ShortSeq	This option is only meaningful if multi-link PPP is negotiated. It proscribes shorter multi-link fragment headers, saving two bytes on every frame. It is not necessary to disable this for connections that are not multi-link.
ACFComp	Address and control field compression. This option only applies to asynchronous link types. It saves two bytes per frame.
ProtoComp	Protocol field compression. This option saves one byte per frame for most frames.

Note

The ppp log files can be found in System ‣ Log Files ‣ General.

Read PPPoE ISP Setup for an example configuration of PPPoE with VLAN Tag for an ISP connection.