Language Selection

English French German Italian Portuguese Spanish

Admins try another weapon against spam

Filed under
Security

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

KDE and GNOME

  • A Simple, Straightforward Clipboard Manager for GNOME
    Clipboard Manager extension for Gnome Shell is a no-frills clipboard manager for GNOME. It adds an indicator menu to the top panel and caches your clipboard history. There’s nothing extra; no regex searching, or cross-device, multi-sync or pan-dimensional magic. Just a simple, easy to access clipboard history. I’ve never been a particularly big clipboard fan. I typically only need to access whatever I copy as I copy it.
  • First GNOME 3.26 Development Release Out, Some Apps Ported to Meson Build System
    GNOME Project's Michael Catanzaro just informed us via an email announcement that the first unstable release of the upcoming GNOME 3.26 desktop environment is out now for public testing and early adopters. Yes, we're talking about GNOME 3.25.1, the first development in the release cycle of GNOME 3.26, which is currently scheduled to launch later this year, on September 13. Being the first unstable release and all that, GNOME 3.25.1 doesn't ship with many changes, and you can check out the CORE NEWS and APPS NEWS for details.
  • Features To Look Forward To In Next Month's KDE Plasma 5.10
    We are just one month away from seeing the next KDE Plasma 5 desktop release.
  • User Question: With Some Free Software Phone Projects Ending, What Does Plasma Mobile's Future Look Like?
    Rosy. While it is true that Plasma Mobile used to be built on the Ubuntu Phone codebase, that was superseded some time ago. The recent events at Ubuntu and other mobile communities have not modified the pace of the development (which is pretty fast) or the end goal, which is to build frameworks that will allow convergence for all kinds of front-ends and apps on all kinds of devices.

Google in Devices

  • Glow LEDs with Google Home
    For the part one, the custom commands were possible thanks to Google Actions Apis. I used API.AI for my purpose since they had good documentation. I wont go into detail explaining the form fields in Api.ai, they have done a good job with documentation and explaining part, I will just share my configurations screenshot for your quick reference and understanding. In Api.ai the conversations are broken into intents. I used one intent (Default Welcome Intent) and a followup intent (Default Welcome Intent – custom) for my application.
  • Google Assistant SDK preview brings voice agent to the Raspberry Pi
    Google has released a Python-based Google Assistant SDK that’s designed for prototyping voice agent technology on the Raspberry Pi 3. Google’s developer preview aims to bring Google Assistant voice agent applications to Linux developers. The Google Assistant SDK is initially designed for prototyping voice agent technology on the Raspberry Pi 3 using Python and Raspbian Linux, but it works with most Linux distributions. The SDK lets developers add voice control, natural language understanding, and Google AI services to a variety of devices.
  • Huawei, Google create a high-powered single board computer for Android
    The Raspberry Pi is very popular with DIY enthusiasts because of the seemingly endless possibilities of how you can design devices with it. Huawei and Google have created their own single board computer (SBC), but this will probably benefit Android developers more than DIY enthusiasts. The HiKey 960 is a very robust SBC aimed at creating an Android PC or a testing tool for Android apps.
  • Huawei’s $239 HiKey 960 wants to be a high-end alternative to Raspberry Pi
    12.5 million sales in five years – Linaro and Huawei have unveiled a high-end (read: expensive) rival.

Mobile, Tizen, and Android