getRemoteAddress() for ColdFusion with or without common load balancers/firewalls

gistfile1.txt

	<cffunction name="getRemoteAddress" output="false" access="public" returntype="string" hint="Identify the remote user IP address">
		<cfset var pc = getHTTPRequestData().headers />
		<cfset var arrIP = "" />

		<cfif structKeyExists(pc, "X-Forwarded-For") AND len(pc["X-Forwarded-For"])>
			<!--- the x-forwarded-for header sometimes includes values that are too long like "172.27.156.64, 67.98.222.16".  The regexp picks out just the matches.  http://support.f5.com/kb/en-us/solutions/public/12000/200/sol12264.html --->
			<cfset arrIP = reMatch('\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b', pc["X-Forwarded-For"]) />
			<cfif arrayLen(arrIP)>
				<cfreturn arrIP[1] />
			<cfelse>
				<cfreturn CGI.remote_addr />
			</cfif>
		<cfelse>
			<cfreturn CGI.remote_addr />
		</cfif>
	</cffunction>