NAME

       interfaces-tunnel - Tunnel extensions for the interfaces(5) file format

DESCRIPTION

       The following options set up tunneling interfaces with ifupdown-ng.

TUNNEL-RELATED OPTIONS

       A tunnel interface must have a mode, remote IP and a local IP or device set, all other
       options are optional.

       tunnel-mode mode
           Denotes the mode for this tunnel. Basically all tunnel modes supported by Linux /
           iproute2 are supported as well.  This includes but is not limited to gre/gretap,
           ip6gre/ip6gretap, ipip/ip6ip/sit.

       tunnel-local IP
           Denotes the IP address used as the local tunnel endpoint.  According to the tunnel-
           mode an IPv4 or IPv6 address has to be given. For compatiblity to ifupdown1 local is
           an alias for this option.

       tunnel-local-dev interface
           When the local IP address the tunnel should be established from isn't static and
           therefore might change (e.g. configured by DHCP or PPP) it might be desireable to just
           use the address configured on interface. When tunnel-local-dev is given instead of
           tunnel-local ifupdown-ng will try to determine the IP address set on the given
           interface with respect to the address family required to set up a tunnel of the given
           mode and use this to set up the tunnel.

       tunnel-remote IP
           Denotes the IP address used as the remote tunnel endpoint.  According to the tunnel-
           mode an IPv4 or IPv6 address has to be given. For compatiblity to ifupdown1 endpoint
           is an alias for this option.

       tunnel-physdev interface
           Denotes the interface the encapsulated packets should be sent out by. This comes in
           handy when using VRFs to denote that the local tunnel endpoint should be terminated in
           VRF interface or the VRF associated with interface.

           Note: Depending on the mode of the tunnel either the VRF interface or the real
           underlay interface may have to given as interface.

       tunnel-ttl ttl
           Denotes the TTL value to use in outgoing packets.  ttl is a number in the range 1 -
           255 whereas 0 is a special value meaning that packets inherit the TTL value.  The
           default for IPv4 tunnels is to inherit the TTL, for IPv6 tunnels it's 64.  For
           compatiblity to ifupdown1 ttl is an alias for this option.

IPIP/SIT-RELATED OPTIONS

       tunnel-encap encap
           Denotes the type of secondary UDP encapsulation to use for this tunnel if any.
           Supported encap values are fou, gue, and none. fou indicates Foo-Over-UDP, gue
           indicates Generic UDP Encapsulation.

GRE-RELATED OPTIONS

       tunnel-encap encap
           Denotes the type of secondary UDP encapsulation to use for this tunnel if any.
           Supported encap values are fou, gue, and none. fou indicates Foo-Over-UDP, gue
           indicates Generic UDP Encapsulation.

       tunnel-key key
           Denotes the_key to used for keyed GRE to allow multiple tunnels between the same two
           endpoints.  key is either a number or an IPv4 address- like dotted quad.  The key
           parameter specifies the same key to use in both directions.  The tunnel-ikey and
           tunnel-okey parameters specify different keys for input and output.  For compatiblity
           to ifupdown1 key is an alias for this option.

       tunnel-hoplimit ttl
           Denotes the Hop Limit value to use in outgoing packets for ip6gre/ip6gretap tunnels.

       tunnel-ignore-df bool
           Denotes wether to enable/disable IPv4 DF suppression on this tunnel.  Normally
           datagrams that exceed the MTU will be fragmented; the presence of the DF flag inhibits
           this, resulting instead in an ICMP Unreachable (Fragmentation Required) message.
           Enabling this attribute causes the DF flag to be ignored.

       tunnel-ikey key
           Denotes the key to used for keyed GRE for packets received.  See tunnel-key for
           details.

       tunnel-okey key
           Denotes the key to used for keyed GRE for packets sent out.  See tunnel-key for
           details.

       tunnel-pmtudisc bool
           Denotes wether to enable/disable Path MTU Discovery on this tunnel.  It is enabled by
           default.  Note that a fixed ttl is incompatible with this option: tunneling with a
           fixed ttl always makes pmtu discovery.

       tunnel-tos tos
           Denotes the TOS value to use in outgoing packets.

EXAMPLES

       A simple GRE tunnel

           auto gre0
           iface gre0
                tunnel-mode gre
                tunnel-remote 198.51.100.1
                tunnel-local 203.0.113.2
                #
                address 192.0.2.42/24
                address 2001:db8::42/64

       A GRE tunnel where the local IP is learned from eth0

           auto gre1
           iface gre1
                tunnel-mode gre
                tunnel-remote 198.51.100.1
                tunnel-local-dev eth0
                #
                address 192.0.2.42/24
                address 2001:db8::42/64

       A GRE tunnel which transfers encapasulated packets via eth0 which is part of a VRF.

           auto eth0
           iface eth0
                address 203.0.113.2/24
                gateway 203.0.113.1
                vrf vrf_external

           auto tun-vrf
           iface tun-vrf
                tunnel-mode gre
                tunnel-remote 198.51.100.1
                tunnel-local 203.0.113.2
                tunnel-physdev eth0
                #
                address 192.0.2.42/24
                address 2001:db8::42/64

           auto vrf_external
           iface vrf_external
                vrf-table 1023

AUTHORS

       Maximilian Wilhelm <max@sdn.clinic>

                                            2024-08-02                       interfaces-tunnel(5)