UNIX System Administration Handbook - Evi Nemeth [215]
syslog
controls how much information is logged via syslog. This option is meaningless if your site does not use syslog. The valid log_levels are listed in the syslogmask man page. The default is syslog upto info.
See Chapter 11 for more information about syslog.
Example:
options noresolv;
Network interface definitions
The properties of network interfaces are set with an interfaces statement, which has the following format:
interfaces {
options [strictinterfaces] ;
define address [broadcast addr] | [pointtopoint addr]
interface iflst [preference prf] [passive] [simplex] ;
[netmask mask] [multicast] ;
};
There may be multiple options, interface, or define statements—or none. This is generally true for all clauses throughout the gated configuration file.
The strictinterfaces option makes it illegal to refer to an interface in the configuration file that cannot be found by the kernel at startup time and that has not been listed in a define statement. This is always an error, but without strictinterfaces turned on, it is not fatal.
The define statement describes a network interface that may or may not be present at startup. It’s mostly used for dial-up links or for other interfaces that might “appear” at a later time. Another good example is a PCMCIA Ethernet card that might be inserted in a slot sometime down the road.
See page 291 for more information about point-to-point links.
An interface statement (repeated here for clarity)
interface iflst [preference prf] [passive] [simplex] ;
sets the options for a particular interface or set of interfaces. iflst can be an interface name such as de0 or le1, a name wild card such as de or le (matching all instances of that type of interface), a hostname or IP address (indicating the interface to which that address is bound), or the literal string all.
If an interface is passive, routes through it will be maintained even if it does not appear to be properly connected. If it’s simplex, the interface cannot receive its own broadcast packets. gated can normally figure this out for itself, but on some systems you may need to say so explicitly.
The preference field requires a more elaborate explanation. Since routing protocols work in different ways and use different cost metrics to determine the “shortest” paths, there’s no guarantee that any two protocols will agree about which routes are best. When the results computed by different protocols are incompatible, an administrative policy must be used to decide which routes are propagated to the kernel’s routing table and exported to other routers.
To implement this policy, gated associates a numeric preference value with each route. When two routes conflict, the one with the lowest preference is the winner of the routing beauty contest.
Preference values can originate from a variety of sources. Every routing protocol has an intrinsic preference value. Preference values can also be assigned to network interfaces and to remote gateways. Since most routes have a protocol of origin and a network interface and a remote gateway, there may be several candidate preference values. gated assigns the most specific of these values. In other words, the path with the lowest numeric preference value (as determined by any of the preference metrics for the path) is the chosen path.
Normally, routes to directly connected networks have a preference value of 0. If it is necessary to prefer one interface over another, you can use preference clauses to prioritize them. Some of the other default preference values used by gated are shown in Table 14.4.
Table 14.4 Default route preference values
The following example sets the interface le0 to be passive, meaning that it will not be used to advertise any routing information:
interfaces {
interface le0 passive;
};
Other miscellaneous