ddt

NAME

DESCRIPTION

DDT (domain debug tools) is a package to help zone administrators to avoid as much as possible these problems, providing a set of commands that allow administrators to analyze any portion of the DNS tree.

DDT works on cached data files because, as such, it can be reasonably efficient. A command is available to try to cache the "real world" situation as close as possible. This command, ddt-xfer(1), is a slightly modified version of BIND's named-xfer(8), that transfers a zone to the cache and, optionally, all its descendents zones. If you have enough disk and bandwith, you can cache all the zones of the world with one only command. Probably, at end, you should start again because some of the cached zones will not reflect the present situation anymore.

The commands read the standard input, and can be given one or more zone files, thus spreading the analisys throughout a set of zones. With the exception of ddt-xfer(1), all commands are written in perl(1).

Available commands are:

ddt-xfer

to cache one or more zones.

soac

to analyze the RRs that describe the zone's authority information, i.e., the NS RRs that list the servers for the zone and a single SOA RR that describe zone management parameters.

rrc

to check the semantic of the RRs, like valid host names, names without trailing dot, etc.

grc

to analyze the glue records for a zone.

mxc

to analyze the MX RRs defined within a zone.

rmc

to analyze the reverse mapping.

Besides these, there are some small scripts to obtain several accounts, like number of hosts, number of nets, number of domains, most popular names, etc. In conjunction with some user written awk scripts, it is easy to obtain a lot of other information. These commands are the following filters:

expand

replaces the owner name of each RR by an absolute or fully qualified name.

hosts

returns all hosts in the zones.

hosts-addr

returns all hosts with their ip-addresses.

hosts-domain

returns all domains defined in the zones with the number of hosts per domain.

cnames

returns all nicknames in the zones.

nets

returns all nets in the zones with the number of hosts per network.

names-stat

counts names.

To help on the interpretation of the several messages returned by the available commands easier, those messages are divided into four levels of severity:

[Warning 1] You should investigate it now!

[Warning 2] Don't forget this warning!

[Warning 3] You should analyze it someday!

[Comment] You can ignore it /

DDT has not enough data to take an effective decision.

Messages belonging to [Warning 1] level are the most serious. On the other hand, messages belonging to [Comment] level are less important, but this doesn't mean that these messages can be completely ignored. Unfortunately, there are some serious errors that were included in the this level because, when the message is displayed, DDT has not enough data (zone files) to take an effective decision.

Each command can take an optional argument, specifying the level of severity of the messages displayed. If it has the value 1, only messages belonging to [Warning 1] level are displayed. If it is 2 all messages belonging to [Warning 1] and [Warning 2] levels are displayed, and so on.

The commands ddt-xfer(1), grc(1), mxc(1), rrc(1), rmc(1) and soac (1) are described in separate manual pages. The scripts for gathering statistics about zones are illustrated below with some examples.

1)

Generate the portuguese statistics of hostnames (all zones below pt. are in /usr/local/ddt.cache/pt directory):

$ expand /usr/local/ddt.cache/pt/* | hosts | names-stat | sort -rn

2)

Count hosts in a zone beginning at the node inesc.pt (the zone inesc.pt is in the file /usr/local/ddt.cache/pt/inesc.pt):

$ expand /usr/local/ddt.cache/pt/inesc.pt | hosts | wc -l

3)

Print the number of hosts by nets in Italy (all zones below it. are in the directory /usr/local/ddt.cache/it):

$ expand /usr/local/ddt.cache/it/* | hosts-addr | nets | sort -rn

Comments and suggestions are welcome.  

SEE ALSO

AUTHORS

Artur Romao <artur@dns.pt>

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