The main focus in Halon 4.5 release is TLS, hence the name “certy”. Check out the the new features and functions and try them out. Also, the knowledge base is growing with a lot of good how-to’s to help you around.
TLS information has been made accessible in the Halon Platform scripting language, both on the receiving and sending side. Support for X.509 client certificates has been added, allowing you to both verify the sender identity in the SMTP server, as well as identify yourself when sending email through an SMTP client.
Experiment: we configured a busy email system to ask for a client certificate for all inbound connections, and found that approximate 5% of all traffic provides a client identity. Most of the traffic is from Gmail and Office356. We did not collect the percentage of domains, which we leave as an exercise for you.
How to enable this feature and start authenticating clients was documented as KB article.
Implementation and facilitation of TLS reporting (tlsrpt) has begun. It is a new standard for reporting TLS failures, mainly focused on MTA-STS and DANE.
The TLSSocket() class now have a getpeercert() function and the ability to specify a client certificate. Now you see why we called it” certy”?
Support for custom SASL authentication mechanism has been added. This allows you to build authentication schemes such as OTP, OAUTHBEARER or CRAM-MD5, but also EXTERNAL to facilitate the client certificate features. The procedure is documented in our knowledge base along with two sample implementations.
If you haven’t found our knowledge base before, the KB is a place to find how-to’s. The dev team is expanding it as fast as we can, adding topics that customers have asked about.
Finally, I want to highlight the big effort we’ve done to simplify, modernize and overall improve the web administration. This is an ongoing project, and something that we’re paying a lot of attention to. We want to thank, and congratulate, the Bootstrap team for providing such a awesome framework. We managed to get the Bootstrap 4.0 release in, with just a few days of work.
We have done two new releases of Halon since last time we updated the blog with release matters. In Halon 4.1 “teamy”, released just before this summer, we introduced modules. A month later we followed up with 4.2 “classy” that added proper object orientation to the language (which works great in combination with modules). It spawned a few rewrites of our script examples (modules) to reflect this awesomeness. We initially added instance and class methods and variables (static), and in 4.3 “cody” we added the private keyword to functions and variables as well.
private $name = "Dr Who?";
$this->name = $name;
return "Hello ".$this->name";
static function ...()
We’ve created a lot of modules and script examples. Some of those, such as the PostgreSQL and MongoDB modules, rely heavily on byte packed data structures. In order to better support those, we’ve added built-in functions such as pack() and unpack(). Upcoming modules and rewrites will also benefit from the new TLSSocket() class.
Here are some new additions to our module collection:
Other notable features from the changelog includes
FreeBSD 11.1 and new quarterly packages
sha2 hash functions
Added status and NDR codes to Reject, Defer and Deliver functions
SetTLS support CA name verification
DLP engine now support file hashes of SHA2-256 and SHA2-512
Added $sourceip variable to post-delivery script to easily determine which IP address that was used to send the mail
Geek out corner
One major change that only we can see and fully appreciate is the (both automated and manual) code migration to C++11 (and forward), using the truly awesome clang-tidy tool.
On another note; while we researched pack and unpack implementations by looking at other languages’ documentation (such as PHP, Perl and Python), we found a bug in PHP, which was fixed in 7.2, and backported to 7.1.9. The overall consensus of syntax and conventions amongst languages regarding how pack and unpack should work seems to reflect and mimic Perl.
“In a language with an automatic garbage collection mechanism, it would be difficult to deterministically ensure the invocation of a destructor, and hence these languages are generally considered unsuitable for RAII [Resource Acquisition Is Initialization]” – Wikipedia on destructors
MongoDB does unlike many other databases use little endian and not big endian (network byte order) in its wire protocol. This will let you send and receive data structures in native machine endian (for most people) since both x86 and amd64 use this convention. I highly recommend reading up on the fun historic trivia about endianness.
Want more in-depth info on the new releases? Get in touch with the support team.
In certain situations it can be very helpful to be able to quickly check if a SMTP server is online and reachable, has support for TLS and that it’s working, test user authentication and measure transaction delays and throughput. All of this and more can be done quickly using the command-line. Here’s your guide!
Today’s leading spam filter technologies offer a very high degree of accuracy. In this blog I’ll describe the current state of spam classification, and propose a pretty innovative method that can significantly improve both senders’ and recipients’ satisfaction (as well as reducing the burden on administrators and support staff) by enabling senders to report false positives if they pass a CAPTCHA test. Let’s start by familiarising ourselves with the history of anti-spam.
The terminology that we normally use is
False positive, a blocked desired (legitimate) email (“ham”)
False negative, a missed spam that slipped through filters into a user’s mail box
Historically, spam filters had poor accuracy and low performance, and email was scanned after being accepted (probably as a consequence of the former). Finding themselves unable to reject email, they offered actions such as putting suspected spam in a junk folder, quarantine or by tagging the subject line.
This I believe, significantly damaged people’s trust in email as a reliable transport, simply because it makes legitimate (potentially important) email disappear.
The leading spam classification technologies today however, offers both high accuracy and performance. Many of them, including Cyren (that we use), uses fuzzy checksums (or “patterns”) to measure and classify email in a distributed, collaborative fashion. By constantly updating the hashing logic, anti-spam vendors are able to adopt as spammers evolve their tactics. By primarily looking at individual spam “outbreaks”, the false positive ratio is generally low in such systems. This is key, since people tend to be much less bothered by a few false negatives (missed spam) rather than having desired email blocked.
The high accuracy and performance also makes rejecting spam (rather than accepting it) a viable option. Rejecting spam is arguable superior to accepting and quarantining it, since the sender is informed about the email not being delivered to the recipient’s inbox. It reestablishes email as a reliable (transactionally safe) transport, while a copy of (the rejected) spam can still be retained in a quarantine of junk folder. Halon has advocated for this approach for a long time, and it’s a prerequisite for efficient feedback and reporting mechanisms like the one I’m going to describe now.
Using CAPTCHA to handle false positives
While I believe that our default approach of rejecting (giving a 500-error) spam with an informative error message (and storing a copy in a quarantine or junk folder) is superior to a traditional quarantine, there sure is room for improvement. For example, the sender needs to contact the recipient using some other mean (alternative email or phone, which they might not have), the quarantine might consume a significant amount of disk space, and the recipient might need to bother the support staff.
We’ve developed a self-service false-positive report and release project simply called sender-fp-release to address those shortcoming. As it says on its Github page, it allows senders to report false positives directly to the recipient after completing a reCAPTCHA.
In our experience, this system is a win for everybody;
The sender doesn’t need to manually contact the recipient, only verify a CAPTCHA
The recipient gets notified instantly, instead of having to browse through a junk folder
The helpdesk doesn’t need to do anything
Additionally, it saves disk space by only retaining spam for a short time (for example 1 day), unless the sender reports it. The retention time for reported email is extended (typically a week or two), giving the recipient plenty of time to release the email.
Although many customers prefer to use the Halon SMTP Platform as-is, most hosting providers want to implement end-user interfaces in order to offer a higher degree of customer self-service. Since the Halon SMTP platform is essentially a scriptable MTA (with many features such as anti-spam, signing, and much more) with an opensource ecosystem, it makes a lot of sense to maintain the end-user interface as a GitHub project. It is designed as a boiler-plate, and our aim is that the code itself should be as simple and straight-forward as possible. It currently offers features such as indexed history, text logs, queue and quarantine management, black/whitelisting, spam settings and statistics.
In the previous weeks, we’ve added translation support using gettext, with English as the default language, and an extra translation in Swedish. If you want to maintain a translation in another language; please let us know! The language is automatically detected based on the browser’s HTTP_ACCEPT_LANGUAGE.
One of Halon’s strengths is seamless integration, something that we discussed in the previous blog entry. The same goes for the end-user interface, and we’ve done numerous integrations with common hosting platforms such as WHMCS, cPanel and Odin. The cPanel plugin is branched out into its own project, and offers session transfer for both admins and users (webmail). We recently went to Barcelona for an APS2 training hosted by Odin, and we’ve published an initial version of our Service Automation plugin. It currently offers session transfer for both admins and users, and we’re looking to extend its functionality in various ways.
We hope that you and your customers will enjoy the updated end-user experience! Do not hesitate to contact us if you want more information or help setting it up.
Thanks to PHP’s flexibility, we could develop a cross-platform solution, without having to rely on a RPC multiplexer. We chose a select()ing method provided by CURL’s “multi” package, by extending the SoapClient class and implementing our own __doRequest.
// Just demonstrating that it works with multiple functions, to multiple servers
$client1 = new SoapClientAsync('some-systems-wsdl', $options);
$client2 = new SoapClientAsync('another-systems-wsdl', $options);
$result1 = $client1->someFunction($arguments);
$result2 = $client1->anotherFunction($arguments);
$result3 = $client2->anotherFunction($arguments);
We hope that our customers appreciate the speed boost that it gives their anti-spam system’s end-user web interfaces.
The Halon MTA is a flexible email operations and security platform.
It enables organisations that operate large-scale email services to offer competitive features by rapid implementation
and to lower maintenance costs through reliable deployment and reduced complexity.