Thanks for the insight, everyone. After studying andye's and dmmiller2k's suggestions, I was able to come up with a somewhat functioning framework. It was tye's comment that really brought it all home, though. \w does not include spaces, but it does include numbers. Doh! (Upon reflection, my example input data file is a very poor example, indeed.) The solution lied in constructing a character class of [\s\Wa-zA-Z]+.

For completeness' sake, following is the final regex: 

(                 # $1 - first IP
\d{1,3}     # 1-3 digits
(?:              # grouping for rep count
\.                # dot
\d{1,3}     # 1-3 digits
){3}          # three more times
(?:             # optional extra grouping
\/               # a slash
\d+           # 1st port number
)?              # close extra grouping
)                # close group around 1st IP
[                # set up character class
\s              # whitespace
a-zA-Z    # letters
\W           # non-word characters
]+             # end character class
(                # $2 - 2nd IP
\d{1,3}   # 1-3 digits
(?:            # grouping for rep count
\.              # dot
\d{1,3}   # 1-3 digits
){3}         # three more times
(?:            # optional extra grouping
\/              # a slash
\d+           # 2nd port number
)?              # close extra grouping
)                # close group around 2nd IP
/x )           # specify /x

[download]

Thanks again!

Update: Fiddled with the grammer.

If things get any worse, I'll have to ask you to stop helping me.

In reply to (shockme) Re: Regex for IP and Optional Port by shockme
in thread Regex for IP and Optional Port by shockme

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.