coredns/plugin/log

log

Name

log - enables query logging to standard output.

Description

By just using log you dump all queries (and parts for the reply) on standard output. Options exist to tweak the output a little.

Note that for busy servers this will incur a performance hit.

Syntax

log

• With no arguments, a query log entry is written to stdout in the common log format for all requests

Or if you want/need slightly more control:

log [NAME] [FORMAT]

• NAME is the name to match in order to be logged
• FORMAT is the log format to use (default is Common Log Format)

You can further specify the class of responses that get logged:

log [NAME] [FORMAT] {
    class [success|denial|error|all]
}

Here success denial and error denotes the class of responses that should be logged. The classes have the following meaning:

• success: successful response
• denial: either NXDOMAIN or NODATA (name exists, type does not)
• error: SERVFAIL, NOTIMP, REFUSED, etc. Anything that indicates the remote server is not willing to resolve the request.
• all: the default - nothing is specified.

If no class is specified, it defaults to all.

Log Format

You can specify a custom log format with any placeholder values. Log supports both request and response placeholders.

The following place holders are supported:

• {type}: qtype of the request
• {name}: qname of the request
• {class}: qclass of the request
• {proto}: protocol used (tcp or udp)
• {when}: time of the query
• {remote}: client's IP address
• {size}: request size in bytes
• {port}: client's port
• {duration}: response duration
• {rcode}: response RCODE
• {rsize}: response size
• {>rflags}: response flags, each set flag will be displayed, e.g. "aa, tc". This includes the qr bit as well.
• {>bufsize}: the EDNS0 buffer size advertised in the query
• {>do}: is the EDNS0 DO (DNSSEC OK) bit set in the query
• {>id}: query ID
• {>opcode}: query OPCODE

The default Common Log Format is:

`{remote} - [{when}] "{type} {class} {name} {proto} {size} {>do} {>bufsize}" {rcode} {>rflags} {rsize} {duration}`

Examples

Log all requests to stdout

. {
    log
    whoami
}

Custom log format, for all zones (.)

. {
    log . "{proto} Request: {name} {type} {>id}"
}

Only log denials for example.org (and below to a file)

. {
    log example.org {
        class denial
    }
}