Technical data

Gateway Routing Daemon (GATED) Configuration Reference
A.18 Control Statements
exact Specifies that the mask of the destination must match the
supplied mask exactly. This is used to match a network,
but no subnets or hosts of that network.
refines Specifies that the mask of the destination must be more
specified (for example, longer) than the filter mask. This is
used to match subnets or hosts of a network, but not the
network.
between lownumber
and highnumber
Specifies that the mask of the destination must be as or
more specific (for example, as long as or longer) than the
lower limit (lownumber) and no more specific (for example,
as long as or shorter) than the upper limit (highnumber).
Note that
exact and refines are both special cases of
between .
• all
This entry matches anything. It is equivalent to:
0.0.0.0 mask 0.0.0.0
• default
Matches the default route. To match, the address must be the default address
and the mask must be all zeros. This is equivalent to:
0.0.0.0 mask 0.0.0.0 exact
• host host
Matches the specific host. To match, the address must exactly match the
specified host and the network mask must be a host mask (i.e. all ones). This
is equivalent to:
host mask 255.255.255 exact
A.18.2 Matching AS Paths
An AS path includes a list of autonomous systems that routing information has
passed through to get to a specified router, and an indicator of the origin of this
list. This routing information can be used to prefer one path to a destination
network over another. The primary method for preferring a route with GATED is
to specify a list of filters to be applied to AS paths when importing and exporting
routes.
Each autonomous system that a route passed through prepends its AS number to
the beginning of the AS path.
AS path regular expressions are defined in RFC 1164.
A.18.2.1 AS Path-Matching Syntax
An AS path is matched using the following syntax.
aspath aspath_regexp origin ( [ any ] ) | [ igp ] | [egp ] | [ incomplete ] )
aspath aspath_regexp
aspath specifies that an AS matching the aspath_regexp with the specified origin
is matched.
origin ( [ any ] | [ igp ] | [ egp ] | [ incomplete ] )
Gateway Routing Daemon (GATED) Configuration Reference A–33