Language Selection

English French German Italian Portuguese Spanish

Admins try another weapon against spam

Filed under

With the volume of spam showing no sign of abating any time soon, system administrators are beginning to turn to one more weapon - greylisting, a technique which some have found to be remarkably successful.

Craig Sanders, a Melbourne-based independent IT consultant and a long-time sysadmin, said greylisting worked by keeping track of how many times a particular combination of IP address, sender, and recipient had appeared.

"The first time a given combination is seen, the sender is told to 'try again later'. If they try again later (after a configurable time period, usually around five minutes) then the message is accepted. The combination is then remembered and, if seen again, is allowed in without any further delay. Since most viruses only try once for each victim address, and also send from random/forged sender addresses, greylisting is extremely effective at blocking them."

Sanders said greylisting was an important part of any anti-spam/anti-virus arsenal. "It's not the whole solution - nothing is - but it is an essential component," he said.

"I implement it on every mail server I build and currently use the postgrey greylisting program (which works with the Postfix mail server)."

He said greylisting seemed to be popular on the Postfix mailing list and on other mail expert lists, "but that's representative of the experts who are really into mail systems and how they work, rather than representative of the bulk of mail server operators."

Full Story.

More in Tux Machines

today's howtos/technical

Graphics: X.Org Foundation Board of Directors and Vulkan

  • Six Candidates Are Vying For This Year's X.Org Foundation Board
    There are six candidates running for this year's X.Org Foundation Board of Directors with four seats being open this election. Those six candidates for this year's X.Org elections include Eric Anholt (Broadcom), Robert Foss (Collabora), Bryce Harrington (Samsung), Keith Packard (HP), Laurent Pinchart (Ideas on Board), and Harry Wentland (AMD).
  • Vulkan 1.1.71 Released As The First Update To Vulkan 1.1
    The first point release to the Vulkan 1.1 release from earlier this month is now available. Vulkan 1.1 promoted a lot of functionality to core while also officially adding sub-groups and protected content support. This Vulkan 1.1.71 point release adds a new extension and fixes. This first point release to Vulkan 1.1 is officially version 1.1.71. This is because when Vulkan 1.1 was created, Khronos decided not to reset the patch number... Vulkan 1.1 was technically 1.1.70 and not 1.1.0. So now with this first update it's bumped to Vulkan 1.1.71.
  • AMDVLK Vulkan Driver Updated With Improvements For Sub-Groups & Multi-View
    The AMD developers working on their official cross-platform "AMDVLK" Vulkan driver have updated their open-source code-base for Linux users. On Friday the AMD developers pushed to the open-source repository their latest work, their first update since introducing Vulkan 1.1 support back on launch day earlier this month.

Programming: Google Opens Maps APIs, Survey, Firefox Addons and GCC

  • China's open source AI, a GitHub tool for licensing, and more news
  • Google Opens Maps APIs and World Becomes Dev Playground
    Google this week announced that it will open its Maps APIs to video game developers, which could result in far more realistic settings in augmented reality games. With access to real-time map updates and rich location data, developers will have many choices of settings for their games. The APIs will provide devs with what Google has described as a "living model of the world" to use as a foundation for game worlds. Developers will have access to more than 100 million 3D buildings, roads, landmarks and parks from more than 200 countries around the globe.
  • Developers dread Visual Basic 6, IBM Db2, SharePoint - survey
    Stack Overflow’s annual survey has revealed the tools and tech that developers love to hate: Visual Basic 6, IBM Db2 and SharePoint. According to the poll, which took in the views of more than 100,000 devs, Rust is the most loved programming language for the third year running. It is closely followed by Kotlin, which makes its debut in the survey. [...] At the other end of the spectrum is Visual Basic 6, which has been voted most dreaded programming language. Visual Basic 6 is also linked to lower pay, with Stack Overflow saying that devs using it are “paid less even given years of experience”.
  • [Firefox] March Add(on)ness: Momentum (2) vs Grammarly (3)
  • Intel SGX Enclave Support Added To GCC
    The latest feature addition to the GCC compiler this week is support for Intel's new "ENCLV". ENCLV is a new intrinsic that is part of the Intel Software Guard Extensions (SGX). The Enclave happens to be a trusted execution environment embedded into a process with isolated memory regions of Enclaves are protected areas of execution and the ENCLV instruction is needed to put application code into that special mode.

BSD: HAMMER2, Split, and ZFS

  • HAMMER2 Gets Many Fixes On The Latest DragonFlyBSD Git
    The HAMMER2 file-system has been available with install-time support since DragonFlyBSD 5.0 while the latest Git code continues to revise this next-generation FS for DragonFly. Landing overnight in DragonFlyBSD were several HAMMER and HAMMER2 improvements.
  • [Older] Exploring permutations and a mystery with BSD and GNU split filenames

    In summary, gsplit's default file naming behavior is to add a letter to the prefix and suffix of a filename whenever it reaches 26^r - 26 files (with r being the current length of the suffix), so you don't need to worry about running out of filenames (just disk space, haha).  

  • Turbocharging ZFS Data Recovery

    Besides being able to display the new debug information, zdb has another new feature that brings its capabilities on par with the kernel: the ability to set global libzpool variables.