logging Statement
logging {
[ channel channel_name {
( file path_name
[ versions ( number | unlimited ) ]
[ size size_spec ]
| syslog ( kern | user | mail | daemon | auth | syslog | lpr |
news | uucp | cron | authpriv | ftp |
local0 | local1 | local2 | local3 |
local4 | local5 | local6 | local7 )
| null );
[ severity ( critical | error | warning | notice |
info | debug [ level ] | dynamic ); ]
[ print-category yes_or_no; ]
[ print-severity yes_or_no; ]
[ print-time yes_or_no; ]
}; ]
[ category category_name {
channel_name; [ channel_name; ... ]
}; ]
...
};
The logging statement configures a wide variety of
logging options for the nameserver. Its channel phrase
associates output methods, format options and severity levels with
a name that can then be used with the category phrase to
select how various classes of messages are logged.
Only one logging statement is used to define as many
channels and categories as are wanted. If there are multiple logging
statements in a configuration, the first defined determines the logging,
and warnings are issued for the others. If there is no logging statement,
the logging configuration will be:
logging {
category default { default_syslog; default_debug; };
category panic { default_syslog; default_stderr; };
category packet { default_debug; };
category eventlib { default_debug; };
};
channel phraseAll log output goes to one or more "channels"; you can make as many of them as you want.
Every channel definition must include a clause that says whether
messages selected for the channel go to a file, to a particular syslog
facility, or are discarded. It can optionally also limit the message
severity level that will be accepted by the channel (default is
"info"), and whether to include a named-generated time
stamp, the category name and/or severity level (default is not to
include any).
The word null as the destination option for the
channel will cause all messages sent to it to be discarded; other
options for the channel are meaningless.
The file clause can include limitations both on how
large the file is allowed to become, and how many versions of the file
will be saved each time the file is opened.
The size option for files is simply a hard ceiling on
log growth. If the file ever exceeds the size, then
named will just not write anything more to it until the
file is reopened; exceeding the size does not automatically trigger a
reopen. The default behavior is to not limit the size of the file.
If you use the version logfile option, then
named will retain that many backup versions of the file
by renaming them when opening. For example, if you choose to keep 3
old versions of the file "lamers.log" then just before it is opened
lamers.log.1 is renamed to lames.log.2, lamers.log.0 is renamed to
lamers.log.1, and lamers.log is renamed to lamers.log.0. No rolled
versions are kept by default. The unlimited keyword is
synonymous with 99 in current BIND releases.
The argument for the syslog clause is a syslog
facility as described in the syslog manual page. How
syslogd will handle messages sent to this facility is
described in the syslog.conf manual page. If you have a
system which uses a very old version of syslog that only
uses two arguments to the openlog() function, then this
clause is silently ignored.
The severity clause works like syslog's
"priorities", except that they can also be used if you are writing
straight to a file rather than using syslog. Messages
which are not at least of the severity level given will not be
selected for the channel; messages of higher severity levels will be
accepted.
If you are using syslog, then the
syslog.conf priorities will also determine what
eventually passes through. For example, defining a channel facility
and severity as daemon and debug but only
logging daemon.warning via syslog.conf will
cause messages of severity info and notice
to be dropped. If the situation were reversed, with
named writing messages of only warning or
higher, then syslogd would print all messages it received
from the channel.
The server can supply extensive debugging information when it is in
debugging mode. If the server's global debug level is greater than
zero, then debugging mode will be active. The global debug level is
set either by starting the server with the "-d" flag followed by a
positive integer, or by sending the server the SIGUSR1 signal (for
example, by using "ndc trace"). The global debug level can be set to
zero, and debugging mode turned off, by sending the server the SIGUSR2
signal ("ndc notrace". All debugging messages in the server have a
debug level, and higher debug levels give more more detailed output.
Channels that specify a specific debug severity, e.g.
channel specific_debug_level {
file "foo";
severity debug 3;
};
will get debugging output of level 3 or less any time the
server is in debugging mode, regardless of the global debugging level.
Channels with dynamic severity use the server's global
level to determine what messages to print.
If print-time has been turned on, then the date and
time will be logged. print-time may be specified for a
syslog channel, but is usually pointless since syslog also prints the
date and time. If print-category is requested,
then the category of the message will be logged as well. Finally, if
print-severity is on, then the severity level of the
message will be logged. The print- options may be used
in any combination, and will always be printed in the following order:
time, category, severity. Here is an example where all three
print- options are on:
28-Apr-1997 15:05:32.863 default: notice: Ready to answer queries.
There are four predefined channels that are used for
named's default logging as follows. How they are used
used is described in the next section, The category phrase.
channel default_syslog {
syslog daemon; # send to syslog's daemon facility
severity info; # only send priority info and higher
};
channel default_debug {
file "named.run"; # write to named.run in the working directory
severity dynamic; # log at the server's current debug level
};
channel default_stderr { # writes to stderr
file "<stderr>"; # this is illustrative only; there's currently
# no way of specifying an internal file
# descriptor in the configuration language.
severity info; # only send priority info and higher
};
channel null {
null; # toss anything sent to this channel
};
Once a channel is defined, it cannot be redefined. Thus you cannot alter the built-in channels directly, but you can modify the default logging by pointing categories at channels you have defined.
category phraseThere 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; };
As an example, let's say you want to log security events to a file,
but you also want keep the default logging behavior. You'd specify the
following:
channel my_security_channel {
file "my_security_file";
severity info;
};
category security { my_security_channel; default_syslog; default_debug; };
To discard all messages in a category, specify the
null channel:
category lame-servers { null; };
category cname { null; };
The following categories are available:
default
category default { default_syslog; default_debug; };
config
parser
queries
lame-servers
statistics
panic
category panic { default_syslog; default_stderr; };
update
ncache
xfer-in
xfer-out
db
eventlib
category eventlib
{ default_debug; };
packet
category packet
{ default_debug; };
notify
cname
security
os
insist
maintenance
load
response-checks
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