Regex For Identifying IP Addresses (To Extract Field)

I've tried and failed to extract the IP Address field such that it only includes sets of 4 numbers that are all separated by periods.  The built-in Splunk Regex pattern generator always seems to tag additional text or punctuation that makes it took specific. 

For instance, the pattern generator tells me to use this:

(?i) accepted: (?P<FIELDNAME>.*)

That works to find 172.25.97.121 in the line below:

2010-03-16 09:46:57.288/[NioTCPListener, swiftlet=sys$jms, port=4001]/INFORMATION/connection accepted: 172.25.97.121

But the same Regex doesn't find the same IP address in this line:

2010-03-16 09:45:15.986/sys$jms/INFORMATION/JMSConnection v630/172.25.97.121:2355/connection closed

Any ideas?

Thanks,

Swack