Reverse IP Address Lookup with ColdFusion + Java

January 10, 2007

I needed to do a reverse lookup on some IP addresses in a database today. I found that you can do this pretty easily with java, and just as easily with ColdFusion. Here it is:

<cfset inet_address = CreateObject("java", "")>
<cfset host_name = inet_address.getByName("").getHostName()>

In java this would simply be:

System.out.println("").getHostName() );

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Or you could use: <cfscript> writeOutput(CreateObject("java", "").getByName("").getHostName()); </cfscript> [ ]'s great post =)
OR: <cfoutput>#CreateObject("java", "").getByName("").getHostName()#</cfoutput> As well =))
Right on Fernando - I wasn't trying to make it look easier in java, but after reading the post again some might have come away with that. The same shortcuts I used in the java example could be used in ColdFusion as you did, above.
Wow. I had a need for using the InetAddress Java class today as well. I planned on blogging it, but you beat me to it.
Has anyone ever done business with They
We also use inet_address.getLocalHost().getCanonicalHostName() for one of our sites in a cluster so if a client has an issue we can have them view source and read out the machine name. is a good tool to view information about ip addresses
why not use this accurate ip address locator:
(I know I'm replying to a 4 year old comment, the question was asked and I'm sure the page is hit to this day. I know I needed a reminder how to do this and ended up here.)

Using the Java method is quicker. If an ISP has set reverse DNS records, the library gives you the rDNS in a few milliseconds. A lookup will always take longer.

rDNS is good data to have when you're tracking down CSRFs or badly behaving web spiders. Sometimes content writers won't add a rel="nofollow" to a link or form tag to keep spiders out. Or someone forgets to disallow a page. Googlebot & others are good but don't post data to forms.

(Cross site request forgery [CSRF or XSRF] is *still* the #1 security issue on web apps even in 2011. Visit OWASP to get the top 10 security issues affecting web apps.)

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did you hack my cf?