Re: Using consecutive IPs in a client access file

[Bill Cole]

On 15 Nov 2016, at 13:07, Gomes, Rich wrote:

Just a quick question since I have not found a way in my Googling.
We are  replacing some of our internal Exchange relays with postfix.
Currently we have other internal postfix relays which utilize a client 
access file to allow relaying.
The file contains all single IPs, no ranges.

The exchange servers have some groups of consecutive IPs on their 
allow list, some cover 5 or 6 IPs, others 100.
Is there a way to provide the same list .i.e.
192.168.0.2-12  OK

without:

Listing them all individually
i.e.
192.168.0.2     OK
192.168.0.3     OK
Etc...
Or
Allowing an entire subnet
192.168.0.0/24  OK


If not possible, that's fine, I will just list them by hand, just 
hoping there was a native way to do it.

No, there's not.

However, I happened to have an old Perl script laying around for other 
purposes that took about 2 minutes to turn into something that takes a 
loosely-formatted text file with one IP spec (single, range, or CIDR) 
per line and spits out a Postfix CIDR table with the aggregate of all 
specs in a minimal set of CIDR blocks, each with OK as the action. On 
many systems you'd need to install the Net::CIDR::Lite Perl module for 
this to work. If your input is a clean list of single IPs and ranges, 
one per line, you can remove lines 17-25 (which are an artifact of my 
original script's loose input.)

#!/usr/bin/env perl
# Input file is text with lines of the general form:
#
#  [IP|IP range|CIDR][whitespace+comment]
#
# Ranges are de-spaced, then anything from the first whitespace to EOL 
is discarded
#
# Output is a Postfix CIDR table with lines of form:
#
#  <CIDR><TAB>OK

use Net::CIDR::Lite;

$list=Net::CIDR::Lite->new ;
while (<>)
{
   # de-space ranges
   s/ ?- ?/-/;

   # toss out comments after the IP spec & whitespace
   s/\s+.*//;

   # oops, this was an indented line with no IP spec, move along
   next if ( !  m/./ );

   # canonicalize shorthanded ranges
   if ( m/^\d+\.\d+.\d+\.\d+-\d+$/) {
      s/^(\d+)\.(\d+).(\d+)\.(\d+)-(\d+)$/\1.\2.\3.\4-\1.\2.\3.\5/;
   }
   $list->add_any($_);
}

$list->clean();
@cidrs=$list->list;

foreach $cidr (@cidrs) { print "$cidr\tOK\n"; }