This commit adds support for configuring GRE/IPIP/SIT tunnel interfaces as know
from previous versions of ifupdown. Currently only configuration checks for GRE
and SIT tunnels are implemented.
A tunnel interface configuration could look like this:
auto gre42
iface gre42 inet tunnel
mode gre
local 198.51.100.1
endpoint 203.0.113.2
#
# optional tunnel attributes
ttl 64
mtu 1400
tunnel-physdev eth0
#
address 192.0.2.42/31
address 2001:db8:d0c:23::42/64
auto he-ipv6
iface he-ipv6 inet tunnel
mode sit
endpoint 203.0.113.6
local 198.51.100.66
#
# optional tunnel attributes
ttl 255
mtu 1466
tunnel-physdev vrf_external
#
address 2001:db8:666::2/64
Signed-off-by: Maximilian Wilhelm <max@rfc2324.org>
