@hackage hath0.0.1

Hath is a Haskell program for working with network blocks in CIDR notation. When dealing with blocks of network addresses, there are a few things that one usually wants to do with them:

• Create a regular expression matching the CIDR block(s). This is because grep will throw up if you feed it CIDR.

• Combine small blocks into larger ones. For example, if you have two consecutive /24s, they might combine into a larger /23.

• View the result of block combination in a useful way.

Hath has four modes to perform these functions:

Regexed

This computes a (Perl-compatible) regular expression matching the input CIDR blocks. It's the default mode of operation.

Reduced

This combines small blocks into larger ones where possible, and eliminates redundant blocks. The output should be equivalent to the input, though.

Duped

Shows only the blocks that would be removed by reduce; that is, it shows the ones that would get combined into larger blocks or are simply redundant.

Diffed

Shows what would change if you used reduce. Uses diff-like notation.

Examples:

Combine two /24s into a /23:

$ hath reduced <<< "10.0.0.0/24 10.0.1.0/24"
10.0.0.0/23

Create a perl-compatible regex to be fed to grep:

$ grep -P `hath regexed -i cidrs.txt` mail.log