mirror of
https://github.com/vyos/vyos-documentation.git
synced 2025-11-04 00:02:05 +01:00
266 lines
8.7 KiB
ReStructuredText
266 lines
8.7 KiB
ReStructuredText
.. _tunnel-interface:
|
|
|
|
Tunnel
|
|
======
|
|
|
|
This article touches on 'classic' IP tunneling protocols.
|
|
|
|
GRE is often seen as a one size fits all solution when it comes to classic IP
|
|
tunneling protocols, and for a good reason. However, there are more specialized
|
|
options, and many of them are supported by VyOS. There are also rather obscure
|
|
GRE options that can be useful.
|
|
|
|
All those protocols are grouped under ``interfaces tunnel`` in VyOS. Let's take
|
|
a closer look at the protocols and options currently supported by VyOS.
|
|
|
|
Common interface configuration
|
|
------------------------------
|
|
|
|
.. cmdinclude:: /_include/interface-common-without-dhcp.txt
|
|
:var0: tunnel
|
|
:var1: tun0
|
|
|
|
IPIP
|
|
----
|
|
|
|
This is one of the simplest types of tunnels, as defined by :rfc:`2003`.
|
|
It takes an IPv4 packet and sends it as a payload of another IPv4 packet. For
|
|
this reason, there are no other configuration options for this kind of tunnel.
|
|
|
|
An example:
|
|
|
|
.. code-block:: none
|
|
|
|
set interfaces tunnel tun0 encapsulation ipip
|
|
set interfaces tunnel tun0 source-address 192.0.2.10
|
|
set interfaces tunnel tun0 remote 203.0.113.20
|
|
set interfaces tunnel tun0 address 192.168.100.200/24
|
|
|
|
IP6IP6
|
|
------
|
|
|
|
This is the IPv6 counterpart of IPIP. I'm not aware of an RFC that defines this
|
|
encapsulation specifically, but it's a natural specific case of IPv6
|
|
encapsulation mechanisms described in :rfc:2473`.
|
|
|
|
It's not likely that anyone will need it any time soon, but it does exist.
|
|
|
|
An example:
|
|
|
|
.. code-block:: none
|
|
|
|
set interfaces tunnel tun0 encapsulation ip6ip6
|
|
set interfaces tunnel tun0 source-address 2001:db8:aa::1
|
|
set interfaces tunnel tun0 remote 2001:db8:aa::2
|
|
set interfaces tunnel tun0 address 2001:db8:bb::1/64
|
|
|
|
IPIP6
|
|
-----
|
|
|
|
In the future this is expected to be a very useful protocol (though there are
|
|
`other proposals`_).
|
|
|
|
As the name implies, it's IPv4 encapsulated in IPv6, as simple as that.
|
|
|
|
An example:
|
|
|
|
.. code-block:: none
|
|
|
|
set interfaces tunnel tun0 encapsulation ipip6
|
|
set interfaces tunnel tun0 source-address 2001:db8:aa::1
|
|
set interfaces tunnel tun0 remote 2001:db8:aa::2
|
|
set interfaces tunnel tun0 address 192.168.70.80/24
|
|
|
|
6in4 (SIT)
|
|
----------
|
|
|
|
6in4 uses tunneling to encapsulate IPv6 traffic over IPv4 links as defined in
|
|
:rfc:`4213`. The 6in4 traffic is sent over IPv4 inside IPv4 packets whose IP
|
|
headers have the IP protocol number set to 41. This protocol number is
|
|
specifically designated for IPv6 encapsulation, the IPv4 packet header is
|
|
immediately followed by the IPv6 packet being carried. The encapsulation
|
|
overhead is the size of the IPv4 header of 20 bytes, therefore with an MTU of
|
|
1500 bytes, IPv6 packets of 1480 bytes can be sent without fragmentation. This
|
|
tunneling technique is frequently used by IPv6 tunnel brokers like `Hurricane
|
|
Electric`_.
|
|
|
|
An example:
|
|
|
|
.. code-block:: none
|
|
|
|
set interfaces tunnel tun0 encapsulation sit
|
|
set interfaces tunnel tun0 source-address 192.0.2.10
|
|
set interfaces tunnel tun0 remote 192.0.2.20
|
|
set interfaces tunnel tun0 address 2001:db8:bb::1/64
|
|
|
|
A full example of a Tunnelbroker.net config can be found at
|
|
:ref:`here <examples-tunnelbroker-ipv6>`.
|
|
|
|
Generic Routing Encapsulation (GRE)
|
|
-----------------------------------
|
|
|
|
A GRE tunnel operates at layer 3 of the OSI model and is repsented by IP
|
|
protocol 47.The main benefit of a GRE tunnel is that you are able to carry
|
|
multiple protocols inside the same tunnel. GRE also supports multicast traffic
|
|
and supports routing protocols that leverage multicast to form neighbor
|
|
adjacencies.
|
|
|
|
A VyOS GRE tunnel can carry both IPv4 and IPv6 traffic and can also be created
|
|
over either IPv4 (gre) or IPv6 (ip6gre).
|
|
|
|
|
|
Configuration
|
|
^^^^^^^^^^^^^
|
|
|
|
A basic configuration requires a tunnel source (source-address), a tunnel destination
|
|
(remote), an encapsulation type (gre), and an address (ipv4/ipv6).Below is a
|
|
basic IPv4 only configuration example taken from a VyOS router and a Cisco IOS
|
|
router. The main difference between these two configurations is that VyOS
|
|
requires you explicitly configure the encapsulation type. The Cisco router
|
|
defaults to gre ip otherwise it would have to be configured as well.
|
|
|
|
**VyOS Router:**
|
|
|
|
.. code-block:: none
|
|
|
|
set interfaces tunnel tun100 address '10.0.0.1/30'
|
|
set interfaces tunnel tun100 encapsulation 'gre'
|
|
set interfaces tunnel tun100 source-address '198.51.100.2'
|
|
set interfaces tunnel tun100 remote '203.0.113.10'
|
|
|
|
**Cisco IOS Router:**
|
|
|
|
.. code-block:: none
|
|
|
|
interface Tunnel100
|
|
ip address 10.0.0.2 255.255.255.252
|
|
tunnel source 203.0.113.10
|
|
tunnel destination 198.51.100.2
|
|
|
|
Here is a second example of a dual-stack tunnel over IPv6 between a VyOS router
|
|
and a Linux host using systemd-networkd.
|
|
|
|
**VyOS Router:**
|
|
|
|
.. code-block:: none
|
|
|
|
set interfaces tunnel tun101 address '2001:db8:feed:beef::1/126'
|
|
set interfaces tunnel tun101 address '192.168.5.1/30'
|
|
set interfaces tunnel tun101 encapsulation 'ip6gre'
|
|
set interfaces tunnel tun101 source-address '2001:db8:babe:face::3afe:3'
|
|
set interfaces tunnel tun101 remote '2001:db8:9bb:3ce::5'
|
|
|
|
**Linux systemd-networkd:**
|
|
|
|
This requires two files, one to create the device (XXX.netdev) and one
|
|
to configure the network on the device (XXX.network)
|
|
|
|
.. code-block:: none
|
|
|
|
# cat /etc/systemd/network/gre-example.netdev
|
|
[NetDev]
|
|
Name=gre-example
|
|
Kind=ip6gre
|
|
MTUBytes=14180
|
|
|
|
[Tunnel]
|
|
Remote=2001:db8:babe:face::3afe:3
|
|
|
|
|
|
# cat /etc/systemd/network/gre-example.network
|
|
[Match]
|
|
Name=gre-example
|
|
|
|
[Network]
|
|
Address=2001:db8:feed:beef::2/126
|
|
|
|
[Address]
|
|
Address=192.168.5.2/30
|
|
|
|
Tunnel keys
|
|
^^^^^^^^^^^
|
|
|
|
GRE is also the only classic protocol that allows creating multiple tunnels
|
|
with the same source and destination due to its support for tunnel keys.
|
|
Despite its name, this feature has nothing to do with security: it's simply
|
|
an identifier that allows routers to tell one tunnel from another.
|
|
|
|
An example:
|
|
|
|
.. code-block:: none
|
|
|
|
set interfaces tunnel tun0 source-address 192.0.2.10
|
|
set interfaces tunnel tun0 remote 192.0.2.20
|
|
set interfaces tunnel tun0 address 10.40.50.60/24
|
|
set interfaces tunnel tun0 parameters ip key 10
|
|
|
|
.. code-block:: none
|
|
|
|
set interfaces tunnel tun0 source-address 192.0.2.10
|
|
set interfaces tunnel tun0 remote 192.0.2.20
|
|
set interfaces tunnel tun0 address 172.16.17.18/24
|
|
set interfaces tunnel tun0 parameters ip key 20
|
|
|
|
|
|
Troubleshooting
|
|
^^^^^^^^^^^^^^^
|
|
|
|
GRE is a well defined standard that is common in most networks. While not
|
|
inherently difficult to configure there are a couple of things to keep in mind
|
|
to make sure the configuration performs as expected. A common cause for GRE
|
|
tunnels to fail to come up correctly include ACL or Firewall configurations
|
|
that are discarding IP protocol 47 or blocking your source/desintation traffic.
|
|
|
|
**1. Confirm IP connectivity between tunnel source-address and remote:**
|
|
|
|
.. code-block:: none
|
|
|
|
vyos@vyos:~$ ping 203.0.113.10 interface 198.51.100.2 count 4
|
|
PING 203.0.113.10 (203.0.113.10) from 198.51.100.2 : 56(84) bytes of data.
|
|
64 bytes from 203.0.113.10: icmp_seq=1 ttl=254 time=0.807 ms
|
|
64 bytes from 203.0.113.10: icmp_seq=2 ttl=254 time=1.50 ms
|
|
64 bytes from 203.0.113.10: icmp_seq=3 ttl=254 time=0.624 ms
|
|
64 bytes from 203.0.113.10: icmp_seq=4 ttl=254 time=1.41 ms
|
|
|
|
--- 203.0.113.10 ping statistics ---
|
|
4 packets transmitted, 4 received, 0% packet loss, time 3007ms
|
|
rtt min/avg/max/mdev = 0.624/1.087/1.509/0.381 ms
|
|
|
|
**2. Confirm the link type has been set to GRE:**
|
|
|
|
.. code-block:: none
|
|
|
|
vyos@vyos:~$ show interfaces tunnel tun100
|
|
tun100@NONE: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN group default qlen 1000
|
|
link/gre 198.51.100.2 peer 203.0.113.10
|
|
inet 10.0.0.1/30 brd 10.0.0.3 scope global tun100
|
|
valid_lft forever preferred_lft forever
|
|
inet6 fe80::5efe:c612:2/64 scope link
|
|
valid_lft forever preferred_lft forever
|
|
|
|
RX: bytes packets errors dropped overrun mcast
|
|
2183 27 0 0 0 0
|
|
TX: bytes packets errors dropped carrier collisions
|
|
836 9 0 0 0 0
|
|
|
|
**3. Confirm IP connectivity across the tunnel:**
|
|
|
|
.. code-block:: none
|
|
|
|
vyos@vyos:~$ ping 10.0.0.2 interface 10.0.0.1 count 4
|
|
PING 10.0.0.2 (10.0.0.2) from 10.0.0.1 : 56(84) bytes of data.
|
|
64 bytes from 10.0.0.2: icmp_seq=1 ttl=255 time=1.05 ms
|
|
64 bytes from 10.0.0.2: icmp_seq=2 ttl=255 time=1.88 ms
|
|
64 bytes from 10.0.0.2: icmp_seq=3 ttl=255 time=1.98 ms
|
|
64 bytes from 10.0.0.2: icmp_seq=4 ttl=255 time=1.98 ms
|
|
|
|
--- 10.0.0.2 ping statistics ---
|
|
4 packets transmitted, 4 received, 0% packet loss, time 3008ms
|
|
rtt min/avg/max/mdev = 1.055/1.729/1.989/0.395 ms
|
|
|
|
.. note:: There is also a GRE over IPv6 encapsulation available, it is
|
|
called: ``ip6gre``.
|
|
|
|
.. _`other proposals`: https://www.isc.org/othersoftware/
|
|
.. _`Hurricane Electric`: https://tunnelbroker.net/
|