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There are many categories, so you can send the logs you want to see wherever you want, without seeing logs you don't want. If you don't specify a list of channels for a category, then log messages in that category will be sent to the default category instead. If you don't specify a default category, the following "default default" is used:
category default { default_syslog; default_debug; };
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As an example, if you want to log security events to a file, but you also want to keep the default logging behavior, specify the following:
channel my_security_channel {
file "my_security_file";
severity info;
};
category security { my_security_channel;
default_syslog;
default_debug;
};
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To discard all messages in a category, specify the null channel:
category lame-servers { null; };
category cname { null; };
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The following categories are available:
| default | The catch-all. Many things still aren't classified into categories, and they all end up here. Also, if you don't specify any channels for a category, the default category is used instead. If you do not define the default category, the following definition is used: category default { default_syslog; default_debug; }; |
| config | High-level configuration file processing. |
| parser | Low-level configuration file processing. |
| queries | A short log message is generated for every query the server receives. |
| lame-servers | Messages like "Lame server on ..." . |
| statistics | Statistics. |
| panic | If the server has to shut itself down due to an internal problem, it will log the problem in this category as well as in the problem's native category. If you do not define the panic category, the following definition is used: category panic { default_syslog; default_stderr; }; . |
| update | Dynamic updates. |
| ncache | Negative caching. |
| xfer-in | Zone transfers the server is receiving. |
| xfer-out | Zone transfers the server is sending. |
| db | All database operations. |
| eventlib | Debugging info from the event system. Only one channel may be specified for this category, and it must be a file channel. If you do not define the eventlib category, the following definition is used: category eventlib { default_debug; }; . |
| packet | Dumps of packets received and sent. Only one channel may be specified for this category, and it must be a file channel. If you do not define the packet category, the following definition is used: category packet { default_debug; }; . |
| notify | The NOTIFY protocol. |
| cname | Messages like "... points to a CNAME". |
| security | Approved/unapproved requests. |
| os | Operating system problems. |
| insist | Internal consistency check failures. |
| maintenance | Periodic maintenance events. |
| load | Zone loading messages. |
| response-checks | Messages arising from response checking, such as "Malformed response ...", "wrong ans. name ...", "unrelated additional info ...", "invalid RR type ...", and "bad referral ...". |
The options statement sets up global options to be used by BIND. This
statement may appear only once in a configuration file; if more than
one occurrence is found, the first occurrence determines the actual
options used, and a warning will be generated. If there is no options
statement, an options block with each option set to its default will be
used.
5.4.2.1 Path Names
Table 5-3 lists the path name options.
| directory | The working directory of the server specified as an absolute path. Any non-absolute pathnames in the configuration file are relative to this directory. The default location for most server output files (e.g. TCPIP$BIND_RUN.LOG) is this directory. If you do not specify a directory, the working directory defaults to SYS$SPECIFIC:[TCPIP$BIND]. |
| named-xfer | The pathname of the BIND_SERVER_XFER program that the server uses for inbound zone transfers. If not specified, the default is SYS$SYSTEM:TCPIP$BIND_SERVER_XFER.EXE |
| dump-file | The pathname of the file the server dumps the database to when it receives a SIGINT signal (TCPIP$BIND_SERVER_CONTROL.EXE dumpdb). If not specified, the default is TCPIP$BIND_SERVER_ZONES_DUMP.DB. |
| memstatistics-file | The pathname of the file the server writes memory usage statistics to on exit, if deallocate-on-exit is yes. If not specified, the default is TCPIP$BIND_SERVER_MEMSTATISTICS.LOG. |
| pid-file | The pathname of the file the server writes its process ID in. If not specified, the default is TCPIP$BIND_SERVER.PID. The pid-file is used by programs like TCPIP$BIND_SERVER_CONTROL.EXE that want to send signals to the running nameserver. |
| statistics-file | The pathname of the file the server appends statistics to when it receives a SIGILL signal (TCPIP$BIND_SERVER_CONTROL.EXE stats). If not specified, the default is TCPIP$BIND_SERVER_STATISTICS.LOG. |
Table 5-4 lists the Boolean options.
| auth-nxdomain | If yes, then the AA bit is always set on NXDOMAIN responses, even if the server is not actually authoritative. The default is yes. Do not turn off auth-nxdomain unless you are sure you know what you are doing, as some older software won't like it. |
| deallocate-on-exit | If yes, then when the server exits it will painstakingly deallocate every object it allocated, and then write a memory usage report to the memstatistics-file. The default is no, because it is faster to let the operating system clean up. deallocate-on-exit is handy for detecting memory leaks. |
| fake-iquery | If yes, the server will simulate the obsolete DNS query type IQUERY. The default is no. |
| fetch-glue | If yes (the default), the server will fetch "glue" resource records it doesn't have when constructing the additional data section of a response. fetch-glue no can be used in conjunction with recursion no to prevent the server's cache from growing or becoming corrupted (at the cost of requiring more work from the client). |
| host-statistics | If yes, then statistics are kept for every host that the the nameserver interacts with. The default is no. Note: turning on host-statistics can consume huge amounts of memory. |
| multiple-cnames | If yes, then multiple CNAME resource records will be allowed for a domain name. The default is no. Allowing multiple CNAME records is against standards and is not recommended. Multiple CNAME support is available because previous versions of BIND allowed multiple CNAME records, and these records have been used for load balancing by a number of sites. |
| notify | If yes (the default), DNS NOTIFY messages are sent when a zone the server is authoritative for changes. The use of NOTIFY speeds convergence between the master and its slaves. Slave servers that receive a NOTIFY message and understand it will contact the master server for the zone and see if they need to do a zone transfer, and if they do, they will initiate it immediately. The notify option may also be specified in the zone statement, in which case it overrides the options notify statement. |
| recursion | If yes, and a DNS query requests recursion, then the server will attempt to do all the work required to answer the query. If recursion is not on, the server will return a referral to the client if it doesn't know the answer. The default is yes. See also fetch-glue above. |
The forwarding facility can be used to create a large sitewide cache on a few servers, reducing traffic over links to external nameservers. It can also be used to allow queries by servers that do not have direct access to the Internet, but wish to look up exterior names anyway. Forwarding occurs only on those queries for which the server is not authoritative and does not have the answer in its cache. Table 5-5 lists the forwarding options.
| forward | This option is only meaningful if the forwarders list is not empty. A value of first, the default, causes the server to query the forwarders first, and if that doesn't answer the question the server will then look for the answer itself. If only is specified, the server will only query the forwarders. |
| forwarders | Specifies the IP addresses to be used for forwarding. The default is the empty list (no forwarding). |
The server can check domain names based upon their expected client contexts. For example, a domain name used as a hostname can be checked for compliance with the RFCs defining valid hostnames. Table 5-6 describes the three name checking methods.
| ignore | No checking is done. |
| warn | Names are checked against their expected client contexts. Invalid names are logged, but processing continues normally. |
| fail | Names are checked against their expected client contexts. Invalid names are logged, and the offending data is rejected. |
The server can check names in three areas: master zone files, slave zone files, and in responses to queries the server has initiated. If check-names response fail has been specified, and answering the client's question would require sending an invalid name to the client, the server will send a REFUSED response code to the client. The defaults are:
The check-names option may also be specified in the zone statement, in
which case it overrides the options check-names statement. When used in
a zone statement, the area is not specified (because it can be deduced
from the zone type).
5.4.2.5 Access Control Options
Access to the server can be restricted based on the IP address of the requesting system. Table 5-7 describes the access control options.
| allow-query | Specifies which hosts are allowed to ask ordinary questions. allow-query may also be specified in the zone statement, in which case it overrides the options allow-query statement. If not specified, the default is to allow queries from all hosts. |
| allow-transfer | Specifies which hosts are allowed to receive zone transfers from the server. allow-transfer may also be specified in the zone statement, in which case it overrides the options allow-transfer statement. If not specified, the default is to allow transfers from all hosts. |
The interfaces and ports that the server will answer queries from may be specified using the listen-on option. listen-on takes an optional port, and an address_match_list. The server will listen on all interfaces allowed by the address match list. If a port is not specified, port 53 will be used.
Multiple listen-on statements are allowed. For example,
listen-on { 5.6.7.8; };
listen-on port 1234 { !1.2.3.4; 1.2/16; };
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If no listen-on is specified, the server will listen on port 53 on all
interfaces.
5.4.2.7 Query Address
If the server doesn't know the answer to a question, it will query other name servers. query-source specifies the address and port used for such queries. If address is * or is omitted, a wildcard IP address (INADDR_ANY) will be used. If port is * or is omitted, a random unprivileged port will be used. The default is
query-source address * port *;
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Note: query-source currently applies only to UDP queries; TCP queries
always use a wildcard IP address and a random unprivileged port.
5.4.2.8 Zone Transfers
Table 5-8 describes the zone transfer options.
| max-transfer-time-in | Inbound zone transfers (BIND_SERVER_XFER processes) running longer than this many minutes will be terminated. The default is 120 minutes (2 hours). |
| transfer-format | The server supports two zone transfer methods. one-answer uses one DNS message per resource record transferred. many-answers packs as many resource records as possible into a message. many-answers is more efficient, but is only known to be understood by BIND 8.1 and patched versions of BIND 4.9.5. The default is one-answer. transfer-format may be overridden on a per-server basis by using the server statement. |
| transfers-in | The maximum number of inbound zone transfers that can be running concurrently. The default value is 10. Increasing transfers-in may speed up the convergence of slave zones, but it also may increase the load on the local system. |
| transfers-out | This option will be used in the future to limit the number of concurrent outbound zone transfers. It is checked for syntax, but is otherwise ignored. |
| transfers-per-ns | The maximum number of inbound zone transfers (BIND_SERVER_XFER processes) that can be concurrently transferring from a given remote name server. The default value is 2. Increasing transfers-per-ns may speed up the convergence of slave zones, but it also may increase the load on the remote name server. transfers-per-ns may be overridden on a per-server basis by using the transfers phrase of the server statement. |
The server's usage of many system resources can be limited. Some operating systems don't support some of the limits. On such systems, a warning will be issued if the unsupported limit is used. Some operating systems don't support limiting resources, and on these systems a cannot set resource limits on this system message will be logged.
Scaled values are allowed when specifying resource limits. For example, 1G can be used instead of 1073741824 to specify a limit of one gigabyte. unlimited requests unlimited use, or the maximum available amount. default uses the limit that was in force when the server was started. See size_spec for more details. Table 5-9 describes the resource limit options.
| coresize | The maximum size of a core dump. The default is default. |
| datasize | The maximum amount of data memory the server may use. The default is default. |
| files | The maximum number of files the server may have open concurrently. The default is unlimited. Note: on some operating systems the server cannot set an unlimited value and cannot determine the maximum number of open files the kernel can support. On such systems, choosing unlimited will cause the server to use the larger of the rlim_max for RLIMIT_NOFILE and the value returned by sysconf (_SC_OPEN_MAX). If the actual kernel limit is larger than this value, use limit files to specify the limit explicitly. |
| stacksize | The maximum amount of stack memory the server may use. The default is default. |
Table 5-10 describes the periodic task options.
| cleaning-interval | The server will remove expired resource records from the cache every cleaning-interval minutes. The default is 60 minutes. If set to 0, no periodic cleaning will occur. |
| interface-interval | The server will scan the network interface list every interface-interval minutes. The default is 60 minutes. If set to 0, interface scanning will only occur when the configuration file is loaded. After the scan, listeners will be started on any new interfaces (provided they are allowed by the listen-on configuration). Listeners on interfaces that have gone away will be cleaned up. |
| statistics-interval | Name server statisitics will be logged every statistics-interval minutes. The default is 60. If set to 0, no statistics will be logged. |
All other things being equal, when the server chooses a name server to query from a list of name servers, it prefers the one that is topologically closest to itself. The topology statement takes an address_match_list and interprets it in a special way. Each top-level list element is assigned a distance. Non-negated elements get a distance based on their position in the list, where the closer the match is to the start of the list, the shorter the distance is between it and the server. A negated match will be assigned the maximum distance from the server. If there is no match, the address will get a distance which is further than any non-negated list element, and closer than any negated element. For example,
topology {
10/8;
!1.2.3/24;
{ 1.2/16; 3/8; };
};
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will prefer servers on network 10 the most, followed by hosts on network 1.2.0.0 (netmask 255.255.0.0) and network 3, with the exception of hosts on network 1.2.3 (netmask 255.255.255.0), which is preferred least of all.
The default topology is
topology { localhost; localnets; };
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BIND 8.1 includes support for dynamic updates as specified in RFC 2136 (excluding support for the security mechanism described by RFC 2137). Any update requests received from hosts that are on the server's allowed list will be honored. Dynamic updates allow the addition or deletion of resource records (RR) and RR sets from a specified zone.
When dynamic updates are sent to and accepted by the name server, the name server attempts to update the domain database file with the change, In some BIND implementations, when the the file is updated, the update does not preserve the file formatting and comments.
Instead of updating the domain database file, the TCP/IP Services BIND
server saves the updates to a transaction log file. The default name
for this file is domain_database.DB_LOG. You must search the
log file and manually apply any changes to the domain database file.
5.4.4 Address Match Lists and ACLs
BIND 8.1 uses address match lists for security. Address match lists are lists of elements that can include the following:
The ACLs "any," "none," "localhost," and "localnets" are predefined. Elements can be negated with a leading "!".
When a given IP address or prefix is compared to an address match list, the list is traversed in order, and the first match (regardless of negation) is used. The interpretation of a match depends on whether the list is being used for access control or as a topology.
When used as an access control list, a non-negated match allows access, and a negated match denies access. If there is no match, access is denied. The clauses allow-query, allow-transfer, and allow-update all use address match lists like this. Similarly, the listen-on clause can use negation to define local addresses that should not be used to accept name server connections.
When used with the topology clause, a non-negated match returns a distance based on its postion on the list (the closer the match is to the start of the list, the shorter the distance is between it and the server). A negated match is assigned the maximum distance from the server. If there is no match, the address gets a distance that is further than any non-negated list element, and closer than any negated element.
Because of the first-match aspect of the algorithm, an element that defines a subset of another element in the list should come before the broader element, regardless of whether either one is negated. For example, in 1.2.3/24; ! 1.2.3.13; the 1.2.3.13 element is completely useless, because the algorithm will match any lookup for 1.2.3.13 to the 1.2.3/24 element. Using ! 1.2.3.13; 1.2.3/24 fixes that problem by having 1.2.3.13 blocked by the negation, but all the other 1.2.3.* hosts fall through.
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