I almost forgot to pass along a link to a more comprehensive detailing of postfix’s anti-uce controls…. here. Also, in the last article I briefly mentioned whitelisting. IF you intend to have several blacklists active it will pay to learn how to whitelist before you HAVE to. To do so, I simply created a text file at /etc/postfix/whitelist and int hat file you enter IP address or hostname followed by OK…. like this….
1.2.3.4 OK
goodmachine.com OK
But… of course, there’s a bit more.
Postfix has a NUMBER of tools for rejecting unwanted messages before they get in the door and waste your CPU time on deciding “hey this mail is spam”. Up until recently I’ve mostly used the relays.ordb.org check (which in the last couple months has now gone defunct.) When we started noticing problems with ordb.org’s responsiveness I planned to investigate other blacklisting options and found several. Obviously there are advantages and disadvantages to blacklisting. The first disadvantage is you have turned over control of blocking mail senders to an outside authority and you should familiarize yourself with THEIR policies for listing (and delisting) a server.
Haven’t had the chance to try this one firsthand yet, although I’ve been watching for this. You may be familiar with ies4linux which is a script that uses wine to download/install multiple versions of Internet Explorer on a linux install. (But why oh why would you do this?) For many that do web design it’s a tremendously good idea to test what a website looks like in multiple browsers because they all have their own unique …. quirks. Of course, there are other reasons…. sites that refuse to work with anything but IE. (Blue Cross/Blue Shield for instance has some web apps that will not work with anything else.)
Well… now Internet Explorer 7 is supported by ies4linux….
Anyone that’s setup software raid on a system with multiple storage adapters has probably run into this kind of issue, but I thought I’d mention it. Last weekend I built a machine to replace my server (the server was to be captured into a VM). The main system was going to be installed onto dual IDE drives, the VM partition and other data on dual 400GB SATA drives. Well, install went well after getting past some of the irq issues I mentioned in a previous writeup. md0 was /boot and so on…. (md0 residing on the dual ide drives.) When the system went to reboot though it didn’t get very far. It complained of not finding a boot image (I think that was the message – didn’t make a note.)
I thought I had written about this once before, but when I searched the site to find the solution I had come across before, I couldn’t find my post…. so, sorry if this is a duplication, but I’ve run into this on some AMD 64-bit based system boards. The most recent was based on the nvidia nforce4 chipset. Essentially in booting from either the alternative install cd or livecd for Ubuntu/kubuntu/edubuntu/xubuntu…. there is a freeze in the boot process. It goes for 30 seconds or more looking as though it’s hard frozen, but it does eventually manage to load the installer.
This last week virtualbox announced that they have released a version of their virtualization software as open source. There is a pay version as well with more features. (*read on for features available in the full version.)
While I appreciate them making the core virtualization open source and currently they are likely the most advanced open source virtualization software out there… it is a bit disappointing to see some of the really juicy features in the non-open source version. However, it should be noted that the full version is free for personal use or evaluation.
A few days ago I had reason to investigate iscsi and AoE (ata over ethernet). Both are protocols for sharing a physical drive over the network at the block level. Let me put it in context first. Traditional network file shares have been done like this…. Computer A has a large drive, it’s formatted and available to Computer A and then THAT computer shares it out to computers B-zzzzzzz. iscsi and AoE basically share the bare drive and then computer B can attach to the drive format and make use of it as it’s own. Realistically I see the greatest advantage with this is adding storage to a server.
I’ve done one or two mentions in the past of ways to recover/reset lost windows passwords and thought it was probably time for another “brain dump/web research dump” of things that I’ve run across. This is not just for lost administrator passwords, but could apply to a lost user account password as well. (I’ve found that the mileage varies on the system. NT/2000/XP/2003 are not the only variations, there seem to be variations related to certain Windows updates/etc.) I should also put a disclaimer here that this information is not so you can break into someone else’s windows installation (without their permission), at the very least that’s a privacy violation and at the worst, against the law and unethical. What this is for is a guide to someone that has accidentally locked themself out of their windows install (or in some cases where someone ELSE has locked you out of your own pc.) In other words – don’t use this to crack.
One of the tools I looked at having for my expanding kit has been a usb wireless adapter that would work with minimal install on Windows/Mac or Linux. As you can imagine…. it’s not as straightforward as just getting one that’s compatible with Windows…. well, after much searching I found the D-Link DWL-G122 802.11g Wireless USB adapter…. (Revision B it seems is the one to get…) Anyway, using a generic driver downloadable for the Mac it will work (from ralink http://www.ralinktech.com). On linux, you have choices (isn’t that the truth…) anyway, there is a native driver (from ralink for the RT2571W/RT2671 chipset) and there’s the rt2x00 driver project and it’s also possible (and fairly easy) to install the Windows driver via ndiswrapper.
I’ve noticed several times in the last week a server of mine that is using postfix has rejected messages due to a failure in the lookup at relays.ordb.org. At first, I thought this was just a false positive in the database at ordb… but this morning I finally “caught it” while it was happening and went to pull up the ordb.org web page. It took…. 30-45 seconds and then proceeding to do a search on the rejected IP took another stretch. In looking at the logs it appears that there may be blanket rejections if the ordb.org check times out.
Here’s the postfix config setting….
smtpd_client_restrictions = permit_mynetworks,reject_rbl_client relays.ordb.org