You may want to add additional external address providers, in case dyndns is unavailable.

Here are a few alternatives:

http://www.ipchicken.com/
http://www.whatismyip.com

Here is some parsing code that will generically work on all 3 : (It could be made more paranoid, or cleverer, but this is easy to read): 

my  ($IP_addr)=$content=~m/(\d+\.\d+\.\d+\.\d+)/;

[download]
Better still, use Regexp::Common: (untested) 
use Regexp::Common qw /net/;
my  ($IP_addr)= $content=~ /$RE{net}{IPv4}/ ;

[download]

     "A closed mouth gathers no feet." --Unknown

In reply to Re: Public IP Address by NetWallah
in thread Public IP Address by Anonymous Monk

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