Security Basics mailing list archives
RE: Verifying E-Mail Addresses
From: "Roger A. Grimes" <roger () banneretcs com>
Date: Tue, 24 Oct 2006 19:53:11 -0400
Well, there are a few ways. If you use Windows Server 2003, you can make the user's Universal Principal Name (UPN) suffix match the user's email domain name (which is often the default anyway). If they then log in using their Windows logon UPN Name (e.g. user () domain com), Windows will automatically valid the UPN name for you (and hence, what appears to be the email address to most people). Or if you're not using a Windows logon, but you can script or program behind the scene, you can query the SMTP server using the VRY or EXP command. You have to send a HELO or EHLO first, but then you can use the VRY or EXP command to verify that the email name is valid. SMTP will return a success or failure message, which you can capture with your script and return into the logon function. Roger ***************************************************************** *Roger A. Grimes, InfoWorld, Security Columnist *CPA, CISSP, MCSE: Security (2000/2003/MVP), CEH, yada...yada... *email: roger_grimes () infoworld com or roger () banneretcs com *Author of Professional Windows Desktop and Server Hardening (Wrox) *http://www.amazon.com/gp/product/0764599909 ***************************************************************** -----Original Message----- From: listbounce () securityfocus com [mailto:listbounce () securityfocus com] On Behalf Of Mister Dookie Sent: Tuesday, October 24, 2006 5:03 PM To: security-basics () securityfocus com Subject: Verifying E-Mail Addresses Hello list, Is there a way to verify that an e-mail address (e.g."johnsmith () company com") is valid and exists or does not exist (is a fake e-mail address) without actually sending a message to that address and awaiting the response? Here's why this is a security issue. Our company administers a small "municipal-type" 802.11 network where for limited open-access the only form of ID we require is an e-mail address and a password. We simple don't have the resources to send out e-mails and then have verification and so forth. We are trying to prevent users from entering fake addresses into our system. We want at least a small amount of accountability. We would like to be able to do a quick check, say query an IMAP, POP3, or SMTP and check to see if there is actually an account at that address without sending a verification e-mail and waiting for users to click on a link or get something that bounces back. Does something like that exist? I do recognize that somebody can enter a valid e-mail address that does not belong to them, but we are trying to address one issue at a time. At this point we are just trying to prevent people who give us "dude () dude com" from getting on to our network. Thanks, John ------------------------------------------------------------------------ --- This list is sponsored by: Norwich University EARN A MASTER OF SCIENCE IN INFORMATION ASSURANCE - ONLINE The NSA has designated Norwich University a center of Academic Excellence in Information Security. Our program offers unparalleled Infosec management education and the case study affords you unmatched consulting experience. Using interactive e-Learning technology, you can earn this esteemed degree, without disrupting your career or home life. http://www.msia.norwich.edu/secfocus ------------------------------------------------------------------------ --- --------------------------------------------------------------------------- This list is sponsored by: Norwich University EARN A MASTER OF SCIENCE IN INFORMATION ASSURANCE - ONLINE The NSA has designated Norwich University a center of Academic Excellence in Information Security. Our program offers unparalleled Infosec management education and the case study affords you unmatched consulting experience. Using interactive e-Learning technology, you can earn this esteemed degree, without disrupting your career or home life. http://www.msia.norwich.edu/secfocus ---------------------------------------------------------------------------
Current thread:
- Verifying E-Mail Addresses Mister Dookie (Oct 24)
- Re: Verifying E-Mail Addresses Shane Warner (Oct 25)
- RE: Verifying E-Mail Addresses Oyesanya, Femi (Oct 25)
- Re: Verifying E-Mail Addresses Jon Hart (Oct 25)
- Re: Verifying E-Mail Addresses Martin Knafve (Oct 25)
- Re: Verifying E-Mail Addresses Saqib Ali (Oct 25)
- Re: Verifying E-Mail Addresses MaddHatter (Oct 25)
- RE: Verifying E-Mail Addresses Roger A. Grimes (Oct 25)
- Re: Verifying E-Mail Addresses Kurtis Miller (Oct 25)
- Re: Verifying E-Mail Addresses nick (Oct 25)
- Re: Verifying E-Mail Addresses Ansgar -59cobalt- Wiechers (Oct 25)
- Re: Verifying E-Mail Addresses Dave Ockwell-Jenner (Oct 25)
- Re: Verifying E-Mail Addresses Robert Inder (Oct 27)
- Re: Verifying E-Mail Addresses Roman Shirokov (Oct 27)
- Re: Verifying E-Mail Addresses Matt Lye (Oct 27)
- <Possible follow-ups>
- RE: Verifying E-Mail Addresses Krpata, Tyler (Oct 25)
- RE: Verifying E-Mail Addresses Jimmie Jones (Oct 25)
- RE: Verifying E-Mail Addresses Weir, Jason (Oct 25)
(Thread continues...)
- Re: Verifying E-Mail Addresses Shane Warner (Oct 25)