@ Steve Todorov:
Your regex will not only match 999.999... but also 9999.9999... etc.

I'd rather take this regex:

/^(1\d{0,2}|2(\d|[0-5]\d)?)\.(1\d{0,2}|2(\d|[0-5]\d)?)
\.(1\d{0,2}|2(\d|[0-5]\d)?)\.(1\d{0,2}|2(\d|[0-5]\d)?)$/

this should represent any ip (v4). At least it did in a small test here ;)
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Server IP: 212.124.37.9
Probable Submitter: 84.58.176.33
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