1.5 KiB
Generic Routing Encapsulation (GRE)
Note: GRE tunnels are unencrypted.
GRE tunnels on layer 3 of the ISO/OSI model.
Configuring with ip
To create a tunnel, you can use the following command:
ip link add <interface> type gre remote <remote> local <local> ttl 255
Replace <interface> with the desired interface name, <remote> with the IPv4 of the peer and <local> with your own IPv4.
If you want to establish the tunnel over IPv6 instead, you can replace the mode gre with mode ip6gre.
To delete a tunnel, you can use the following command:
ip link del <interface>
To assign an IP address to the interface, you can use the following command:
ip link del <interface>
To assign an IP address to the interface, you can use the following command:
ip addr add dev <interface> <ll>
Replace <ll> with your own link-local address.
Automatic start with ifupdown
If you want to start the GRE tunnel automatically, you can use an ifupdown template which is placed under /etc/network/interfaces.d:
auto <interface>
iface <interface> inet6 manual
pre-up ip link add <interface> type gre remote <remote> local <local> ttl 255
up ip addr add dev <interface> <ll>
post-down ip link del <interface>
The interface can then be stopped and started accordingly:
ifup <interface>
ifdown <interface>
GRETAP
GRETAP tunnels operate on layer 2 of the ISO/OSI model. To use a GRETAP tunnel, you only have to change the mode: For IPv4 gretap and for IPv6 ip6gretap.