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IFCFG-TUNNEL

NAME
SYNOPSIS
Tunnel interfaces
VARIABLES
Examples for tunnel configurations
BUGS
AUTHOR
SEE ALSO

NAME

ifcfg-tunnel − network tunnel interface configuration

SYNOPSIS

/etc/sysconfig/network/ifcfg-gre*
/etc/sysconfig/network/ifcfg-ipip*
/etc/sysconfig/network/ifcfg-sit*

/etc/sysconfig/network/ifcfg-tun*
/etc/sysconfig/network/ifcfg-tap*

Tunnel interfaces

It is possible to create static IP tunnel interfaces for three different protocols:

	SIT		IPv6 over IPv4 tunnel
	GRE		universal IPv4 tunnel
	IPIP		IPv4 over IPv4 tunnel

Additionally, also creation of user space program driven tunnels using the universal TUN/TAP device driver is supported:

	TAP		Ethernet tunnel interface
	TUN		Point-to-Point IP tunnel interface

Since there is not yet a YaST2 support for creating tunnels one must write appropriate config files by hand for now.

VARIABLES

These variables can used in ip tunnel config files:

TUNNEL

Here you have to set the tunnel protocol. This may be "sit" for IPv6 over IPv4 tunnel, "gre" for universal IPv4 tunnel, "ipip" for IPv4 over IPv4 tunnel and "tap" or "tun" for the user space program driven tunnels.

TUNNEL_LOCAL_IPADDR or TUNNEL_DEVICE

The address of the local tunnel’s end could be directly specified in TUNNEL_LOCAL_IPADDR variable. The address must be present on an existing interface of this host (the TUNNEL_DEVICE). If TUNNEL_LOCAL_IPADDR is empty the first ipv4 address without label from the interface given in the variable TUNNEL_DEVICE will be used. You can configure a label for each additional address on the interface, that you don’t want to use.

TUNNEL_REMOTE_IPADDR

The address of the remote tunnel’s end.

TUNNEL_TTL

Specify the Time To Life of the packet which carries the tunneled data. Usually it is set to 64 but in some circumstances you may want do use something else between 1 and 255. Special value is "inherit" in which case the TTL is copied from the inner (tunneled) packet. This is also the default if the TTL variable wasn’t used.

TUNNEL_OPTIONS

Here you may set additional options for the command ip tunnel add

TUNNEL_SET_PERSISTENT

Create a persistent tun or tap interface. Default is "yes". Non-persistent tunnels are not supported yet.

TUNNEL_SET_OWNER and TUNNEL_SET_GROUP

Allows to set the owner and group (by name or UID/GID) for persistent tun/tap interfaces.

Examples for tunnel configurations

This are some generic examples for different tunnel types. Replace the shown addresses and interface names by your individual ones. As configuration names you may choose the interface names.
GRE and IPIP tunnels

Create a GRE tunnel between a local computer with IP address 192.168.1.2 and a remote computer with IP address 172.16.2.3. After the tunnel is created assign an IP address 10.20.30.40 to it’s local end. Default filename: ifcfg-gre1
STARTMODE=’onboot’
BOOTPROTO=’static’
TUNNEL=’gre’
TUNNEL_LOCAL_IPADDR=’192.168.1.2’
TUNNEL_REMOTE_IPADDR=’172.16.2.3’
IPADDR=’10.20.30.40’
TUNNEL_TTL=’64’

IPIP tunnel is created in exactly the same way, except that the variable TUNNEL has to be set to "ipip" in this case. Use filename ifcfg-tunl1 in this case.

SIT tunnels for IPv6 over IPv4

There are two modes in which SIT tunnels may operate: static and 6to4

To create a "static" tunnel one needs to know an IPv4 address of the remote end, while for a "6to4" tunnel the remote end is a "6to4 relay". These relays are usually public and could be reached either under their respective IPv4 address or under a unique IPv4 anycast address 192.88.99.1 (as defined in RFC 3068).

This typical config file for a 6to4 tunnel should fit most user’s needs and the only required change is the external interface name. Default filename: ifcfg-sit1
STARTMODE=’onboot’
BOOTPROTO=’6to4’
TUNNEL=’sit’
TUNNEL_DEVICE=’eth0’
TUNNEL_TTL=’64’
Additionally you need to set some routes. Do that in a file called ifroute-<configname> with the same configname as in ifcfg-<configname>. Default filename: ifroute-sit1 It may look like this:
2000::/3 2002:c058:6301::1 - - - metric 1
The magic string 2002:c058:6301::1 is a 6to4 version of the anycast IPv4 address 192.88.99.1.

To create a "static" tunnel with local IPv6 address 3ffe:ffff::1234/64 use a config file like this: Default filename: ifcfg-sit1
STARTMODE=’onboot’
BOOTPROTO=’static’
TUNNEL=’sit’
TUNNEL_LOCAL_IPADDR=’192.168.1.2’
TUNNEL_REMOTE_IPADDR=’172.16.2.3’
IPADDR=’3ffe:ffff::1234/64’
TUNNEL_TTL=’64’

Universal TUN/TAP tunnels

The universal TUN/TAP kernel driver provides an interface for user space programs to operate a tunnel. There are two modes in which the interface can be created:
TUN (a Point-to-Point interface using local and remote IP) or
TAP (like normal ethernet interface, e.g. for use in bridges).

The following configuration allows to create the interfaces persistently:

ifcfg-tap0
STARTMODE=’onboot’
BOOTPROTO=’static’
TUNNEL=’tap’
# optionally:
TUNNEL_SET_PERSISTENT=’yes’
TUNNEL_SET_OWNER=’username’
TUNNEL_SET_GROUP=’groupname’

ifcfg-tun0
STARTMODE=’onboot’
BOOTPROTO=’static’
TUNNEL=’tun’
# optionally:
TUNNEL_SET_PERSISTENT=’yes’
TUNNEL_SET_OWNER=’username’
TUNNEL_SET_GROUP=’groupname’

The user space program can be started later, e.g. by the ifservices(5) mechanism. The TUNNEL_SET_OWNER and TUNNEL_SET_GROUP settings allow to run the user space program with an different UID/GID than 0 (root). When not specified, the user space program has to run with UID 0.

Non-persistent tunnels (TUNNEL_SET_PERSISTENT=no), where the user space program (e.g. openvpn) is started directly in ifup, are not supported yet.

BUGS

Please report bugs at <http://www.suse.de/feedback>

AUTHOR

Christian Zoz <[email protected]> -- ifup script
Michal Svec <[email protected]> -- ifup script
Bjoern Jacke -- ifup script
Mads Martin Joergensen <[email protected]> -- ifup manual page
Michal Ludvig <[email protected]> -- tunnel support

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