AHBL (Abusive Host Blocking List) is a DNSBL (Domain Name Service Blacklist) that has been available since 2003 and is used by administrators to crowd-source spam sources, open proxies, and open relays. By collecting the data into a single list, an email system can check this blacklist to determine if a message should be accepted or rejected. AHBL is managed by The Summit Open Source Development...
SSL or Secure Sockets Layer is protocol designed to provide a secure way of transmitting information between computer systems. Originally created by Netscape and released publicly as SSLv2 in 1995 and updated to SSLv3 in 1996. TLS or Transport Layer Security was created in 1999 as a replacement for SSLv3. TLS and SSL are most commonly used to create a secure (encrypted) connection between your...
A code glitch in a new DBL sub-zone known as 'Abused-Legit' caused the new Abused-Legit zone to list ".net." for 60 minutes from 08:35 UTC. — Spamhaus (@spamhaus) December 17, 2014 Spamhaus are rolling out a new subzone of the DBL, for domains whose webservers have been compromised and used to host spam landing pages, often via mass compromises of their management control...
When you’re developing code to handle data it’s almost essential to have a decent sized set of test data, so you can build a test harness to check on functionality and performance as you go. A common way of doing that is to take a snapshot of your production database and pull out an appropriate subset from there. That works pretty well in most cases, but it’s a really bad idea...
Most of the time when we’re talking about email addresses, we’re talking about the actual user@domain format that’s used to send mail over the wire, but that’s not how we most often see them. When they’re used in a To: or From: header they’re usually associated with a display name – the “real name” of the user with the associated email address...
About a month ago someone posted a heavily elided screenshot that they claimed was evidence of their ISP, AT&T, sabotaging SMTP connections being sent over their network, meaning that anyone could sniff their passwords and traffic. This is it: Most email people looking at that saw the asterisks in the banner and went “Oh. That’s not the ISP tampering with the...
SWAKS is a general purpose testing tool for SMTP. For basic SMTP testing it’s a more convenient, scriptable alternative to running a transaction by hand, but it also lets you test things that are difficult to do manually, such as authentication or TLS encryption. It’s a perl script that installs fairly easily on OS X or any Linux/unix system (and can be installed on Windows, if you...
Recipients can’t click through if you don’t exist A tale of misconfigured DNS wrecking someone’s campaign. I got mail this morning from A Large Computer Supplier, asking me to fill in a survey about them. I had some feedback for them, mostly along the lines of “It’s been two decades since I bought anything other than rackmount servers from you, maybe I’m not a...
I just saw an interesting observation on the dmarc-discuss mailing list. Apparently some of the larger providers who are implementing DMARC for inbound email may not be handling some of the grubbier corners of the spec perfectly. That’s not surprising at all – early adopters tend to deploy code that implements early versions of the draft specification – but I can see this...
Last week Alice and Bob showed how to cryptographically sign messages so that the recipient can be sure that the message came from the purported sender and hasn’t been forged by a third party. They can only do that if they can securely retrieve the senders public key – which means they need to retrieve it from the actual sender, rather than an impostor, and be sure it’s not...
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