mkrdns(1)

NAME

mkrdns - MaKe Reverse DNS (auto generate PTR maps)

SYNOPSIS

mkrdns [options] [configuration file]

DESCRIPTION

mkrdns is a program designed to auto-generate reverse DNS

maps (IN PTR records). Some programs already accompany the BIND

source package that will do this kind of thing on a single domain

or network basis. mkrdns will read either a named.boot or

named.conf file, figure out which domains and networks to deal

with, and then generate the reverse maps.

You are deemed "in charge" of a network/domain if you are

the primary DNS for a reverse zone, or if you are either the pri

mary or secondary for a forward zone. The exception to this rule

is that the 127.* network is not auto-generated due to the "1 IN

PTR localhost." issue.

OPTIONS

-debug Print debugging information. (this will

print a LOT of information, be warned.)

-extension <ext> Append the given extension to the output

files. This is useful if you want to
have the reverse maps generated, but want
to check their contents before use.

-hash <hash> Allows you to override the default hash

function. (used to determine if a map
has changed) mkrdns will try to use
MD5 (1) if the Digest::MD5 Perl module is
installed. Otherwise, it'll default to
32-bit checksums (0).

-help The help screen.

-quiet Turn off warning messages (multiple A

records -> IP, etc.) Good for scripts,
but you probably want to check on what
the warnings report.

-rootdir <path> Specify the path to the root directory

that named will be running in. This
will handle anyone using a chrooted
environment for named. Everything except
the configuration file is assumed to be
under the new root.

-version Show mkrdns version information.

CONFIGURATION FILE

mkrdns reads the standard BIND configuration files

named.boot and named.conf. If you don't specify the full path to

the file on the command line, mkrdns assumes that one (or both)

will exist in /etc and will search for them. If none are found,

the program exits. If one is found, it is used. If both are

found, named.conf is used.

DIRECTIVES

Directives are new in mkrdns since version 1.2. Think of

directives as configuration options for mkrdns which are simply

comments to BIND. The current directives are map, serialt, skip,

and skipzone.

Map allows you to map hosts to another network. This was

designed in for the purpose of handling DNS for a subnet of a

class C network which you do not control. (See the DNS & BIND

O'Reilly and Associates book, 3rd Ed., pg. 215-218) Assume that

you have 10.4.4.32/27 (ie: you have the 32 IPs from 10.4.4.32 to

10.4.4.63 ...) You want to do reverse mappings for those IPs,

but you don't control 4.4.10.in-addr.arpa. How do you do it?

The solution is to become the master for another zone (such as

32.4.4.10.in-addr.arpa. or 32-63.4.4.10.in-addr.arpa.), and CNAME

the correct reverse pointers to the ones you're in charge of.

The format for the directive is:

map <network/mask> <new network>

Ex: map 10.4.4.32/27 10.4.4.32-63

This maps all hosts between 10.4.4.32 and 10.4.4.63 to

10.4.4.32-63.32 to 10.4.4.32-63.63.

Serialt will change mkrdns's behavior with the serial num

ber for certain zones. By default (and in all pre-1.6 versions of

mkrdns), the serial number is assumed to be in date format

(YYYYMMDDVV, year/month/day/version). As of v1.6 you can force

mkrdns to treat it as a regular number instead. This allows for

more than 100 zone changes a day, and has a bit more flexibility

depending on the environment. The format for the directive is:

serialt <zone> <format>

<zone> is either "default" or the actual zone (ie:

0.0.0.10.in-addr.arpa). <format> is either "date" or "number".

Ex: serialt 1.168.192.in-addr.arpa number

Skip forces mkrdns to ignore certain hosts/IPs via regular

expression. The concept is that there are some IN A records that

you would like to skip and not create a reverse entry. Skip al

lows this. (for instance, "foo IN A 10.4.4.32" and "mail IN A

10.4.4.32" both exist, but you want to force foo as the reverse

lookup and ignore mail. The following example can do this for

you.) Format:

skip <regular expression>

Ex: skip ^mail

This will skip any host (or IP) that matches the "^mail"

regular expression. The host is the FQDN, and the IP is before

mapping (see above).

Skipzone forces mkrdns to ignore certain zones while pro

cessing the named configuration file. A possible use for this is

where you have "bar.com" and "bar.net", and both of them should

have the same host info (ie: foo.bar.com and foo.bar.net both

have the same records.) You want "bar.com" to be the reverse

lookup for the IPs used. So set the zone file setting to the

same file (bar.zone), and then add "skipzone bar.net". NOTE:

The skipzone argument must match EXACTLY with the zone name in

the config file. NOTE: You can specify multiple zones in the

same "skipzone" statement. (ie: "skipzone foo.com bar.com")

The format of a directive differs (sorry) between

named.conf and named.boot. UNIX-style comments (the hash mark

then the comment) are allowed.

named.boot directives

Directives look like a comment, so the format is simply:

; mkrdns <directive type> <parameters>

named.conf directives

To make directives more efficient with BIND 8, the format

is slightly different:

/* mkrdns

<directive type> <parameters>
...

*/

EXAMPLES

mkrdns -e new /etc/named.boot

This will run mkrdns over the file /etc/named.boot. Out

put files will be generated as <name>.new (i.e.: if the PTR zone

file is called 160.zone, the output will be 160.zone.new.)

NOTES

I tend to use this script like a lint check. i.e.: Edit

the proper zone files, then run mkrdns.

As with most documentation, there are probably things that

aren't mentioned in the docs that the script does/assumes/etc. I

apologize for any inaccuracies/omissions. Let me know if there

are any parts that have an "issue", and I'll see if I can't

straighten it out.

ASSUMPTIONS

- the <network>.zone reverse map files must already be

created, and have the appropriate information (SOA/NS records,

etc.) in there. This script will strip out any PTR records, and

then add them back in. (This means anything like blank lines and

comments will be moved to the top of the file.) $ORIGIN and $IN

CLUDE are striped as of mkrdns 1.3.

- you must be at least a secondary for all domains which

reference IP networks for which you're responsible. There is no

means (currently at least) to specify a PTR record for a non-ex

istent A record, so this script must have access to all A records

that need to be "reversed".

- if you have more than 1 A record pointing to a specific

IP, you can't have both be the PTR record. This script takes the

first A record it sees as the one used for the PTR record. A

warning is printed for any additional entries. (While the RFCs

don't prohibit multiple PTR records for the same IP, I have yet

to find anyone who can give me a good reason to do it.)

- map serial numbers default to be in YYYYMMDDVV format.

(YYYY = year, MM = month, DD = day, VV = version (00-99). This

script will convert your serial number to this format if it's not

already. I don't have too many daily DNS changes, so the action

for not being able to update the serial number (ie: VV is at 99

and can't be increased) is to simply exit. If this is going to

cause a problem for you, you can use the serialt directive to

specify a zone (or the default) should treat the serial number as

a number instead of using the date format. Either way, a problem

will come up when the serial number reaches 4294967295 (max val

ue), but that's another story. (mkrdns will print a warning if

this is about to happen)

AUTHOR

Theo Van Dinter <felicity@mkrdns.org> <tvd@colltech.com>

perl v5.8.8 2001-08-28

MKRDNS(1)