After getting in closer-than-usual acquaintance with my mail server logs I thought I’d share a brief note I found in the Spamhaus PBL FAQ:
The first thing to know is: THE PBL IS NOT A BLACKLIST.
Oh, and since you’re already there you may want to linger a bit in this warning:
WARNING! Some post-delivery filters use “full Received line traversal” or “deep parsing”, where the filter reads all the IPs in the Received lines. Legitimate users, correctly sending good mail out through their ISP’s smarthost, will have PBL-listed IPs show up in the first (lowest) Received header where their ISP picks it up. Such mail should not be blocked! So, you should tell your filters to stop comparing IPs against PBL at the IP which hands off to your mail server! That last hand-off IP is the one which PBL is designed to check. If you cannot configure your filters that way, then do not use PBL to filter your mail. Instead, you may wish to use sbl-xbl.spamhaus.org, but even that may have unacceptable “false positive” filtering, for example when a an exploited end-user machine sends legitimate mail out through the ISP smarthost, or when the dynamic assignment changes the IP to an uninfected machine. Do not use PBL or XBL if you do not understand the issues of “deep parsing”.
So if your top-of-the-line multi-thousand-dollar antispam appliance starts blocking all my email just because there’s a dynamic IP address somewhere in the header and there’s no freaking way to turn it off please go ask for a refund. And stop bouncing my messages.
Oh and by the way the default SpamAssassin configuration in Debian assigns a 0.905 score if the last hop is in PBL.
score RCVD_IN_PBL 0 0.509 0 0.905
header RCVD_IN_PBL eval:check_rbl('zen-lastexternal', 'zen.spamhaus.org.', '127.0.0.1')
And yes, SpamAssassin does the right thing and checks only the *last* external address — I’ve seen the code:
# If name is foo-lastexternal, check only the Received header just before
# it enters our internal networks; we can trust it and it's the one that
# passed mail between networks
So once again kudos to Open Source — and Common Sense.
A few weeks ago I upgraded my wife’s iPod Touch to 2.1, and I just can’t believe that iTunes won’t let you backup your content even if it means a paid firmware upgrade. I would have used PodsBlitz to back it up, except that Apple decided that it would be a good idea to strip off the disk mode from the iPod Touch.
I decided that there was nothing to be done for the music files: I would have copy the files manually after the upgrade, hoping to replicate my wife’s original selection as closely as possible. But that iPod also has a few of my daugther’s favorite movies… I rightly believed we could have a problem there. I’ve been converting her favorite DVDs for a year, and I carelessly deleted the converted files from the PC a long time ago leaving two options: either invest a few afternoons re-converting those DVDs, or somehow get those files out of the iPod and restore them later.
After a few google searches I stumbled upon a couple of promising projects that some day may grant you unrestricted access to the media residing in your iPod Touch, but those just refused to work in my wife’s PC. A few more queries later I found DigiDNA DiskAid, a nice little utility that speaks the iPod’s obscure file transfer protocol over USB and that lets you copy files back and forth. It’s far from perfect — it wiill only show the physical filename instead of the “real”, tag-based one, and it only does alphabetical sorting, even when sorting by file size. This made hunting for those movie files kind of annoying — annoying but *possible*, which is a lot more that can be said for Apple’s tools.
After pulling my hair for a couple of days I just realized that my DSL provider is blocking all outgoing connections to port 25 with an ICMP Unreachable packet, which translates as a totally bogus “no route to host” message (An ICMP RST would be more kosher, BTW). The only explanation that comes to my mind is that Telmex has finally realized that it has become one of the largest botnet hosts in the world and decided to do something about it. This is a terrible inconvenience for me, because I run a backup MX at my home office and all the email I write while I’m at home is relayed through it. And now it believes that it has been cut out from the Internet, and is suffering from Internet withdrawal syndrome. Oh, and all attempts to use an external relay -like my primary MTA or the office’s- through port 25 fail as well, so I have had to set up an elaborate workaround *just to send email*.
*Argh!* I hate to pay up for those ignorant Windows home users.
Add to that the fact that i get 800KBps tops in a 2GBps line, and recurrent reports of arbitrary bandwidth capping and Infinitum stops looking like a good alternative for home broadband. I’ll have to look for a cost-effective alternative, but after experiencing 20MBps/20EUR in Europe I’m afraid that I’ve been spoiled for life.
In the meantime, if you were expecting a mail from me in the last five days or so, I’m sorry to say that it is either on its way or lost forever.
Anyway… Merry Christmas!
Update 20080104: AJ Gibson points out in a comment that Telmex is willing to remove the block from your account if you are willing to jump through a few hoops. Just go to http://www.telmex.com/mx/asistencia/correoelectronico/faq_puerto_25.html and follow the instructions there. I registered yesterday and today I can connect back to external SMTP servers again. As mentioned in the comments, YMMV.
The product you are in charge of maintaining has been in active use for a decade. The manual is several megabytes long, and there’s an army of programmers, consultants and technical writers that make a living off it. As you might guess, it’s not an inexpensive product.
One of the routine tasks for that product -let’s say, “create a new UCM project”- is throughtly documented for the GUI use case, but the manual makes absolutely no mention of the CLI-based procedure. You go through the whole procedure armed with the aforementioned documentation and lots and lots of patience, second-guessing the developers and the technical writers every step of the way, but getting the work done with varying amounts of effort and frustration.
Then, in a key command, you hit a wall. The program complains:
Created project "gpa3_project".
cleartool: Error: Unknown policy name "POLICY_DELIVER_NCO_SELACTS" specified.
cleartool: Error: Cannot set all the policy pvars on project "gpa3_project".
Project "gpa3_project" is now ClearQuest-enabled and
linked to ClearQuest database "COFCQ".
Now “POLICY_DELIVER_NCO_SELACTS” returns *exactly* one match in Google, and it points to the aforementioned documentation. It’s “POLICY_DELIVER_NCO_SELACTS” all over.
After a lot of frustration,
strings /opt/rational/clearcase/linux_x86/shlib/libatriasum.so|grep -i policy_|sort
shows that “POLICY_DELIVER_NCO_SELACTS” is a typo. They really meant “POLICY_DELIVER_NCO_SELACT” instead. No final “S”, you see! And this happened SOME TIME IN THE LAST TEN FREAKING YEARS.
The list of things I’d like to do to the project managers, documentors, and technical writers of this particular product suite is too graphic even for the Internet.
And most importantly — how do they get away with these levels of incompetence?