Gypsy Lovers

09/20/04 | by david2 [mail] | Categories: General

Stopping spam with qgreylist

09/19/04 | by david2 [mail] | Categories: General, Geek
The theory is this: most spammers use software which is intent on getting as much mail out as quickly as possible. This means that if the receiving end has a temporary error, and temporarily rejects the email, the spamming computer ignores it and moves on to the next computer, whereas normal email servers will make a second attempt.

So, this software takes advantage of that: email from unknown servers is temporarily rejected. Spammers move on, and real email servers resend.

In effect, this is raising the cost of sending an email to someone with this program running. It's not a great cost, but for now it's a cost that the spammer is not spending, and therefore can be used to block the mass of spam. I imagine that the spammers will eventually add some sort of workaround, but for now, it's a simple and very effective service.

Email purists will say that this intentionally breaks the email protocols, which is debatable: issuance of a temporary error is allowed, but presumably only when there actually IS a temporary error. So this may be best viewed as skirting the intent of the email protocols.

In any event, it works. And by that, I mean it works really well .

If you're running qmail, then this script by jon atkins is the thing.

However, if you're running Solaris, it won't work because it makes use of the Sys::Syslog module in perl, which is notoriously broken in many stock versions of Solaris. So, instead, you can use this code here which I modified to use Unix::Syslog . You'll need to install that module by either downloading it from www.cpan.org, or downloading it with the cpan module. An example of doing this would be:

unixprompt> perl -MCPAN -e install Unix::Syslog <enter>

invoking a perl module

09/18/04 | by david2 [mail] | Categories: Geek
perl -MCPAN -e shell

Turtles all the way down

09/15/04 | by david2 [mail] | Categories: General
Turtles all the way down

Stephen Hawking in A Brief History Of Time starts with the anecdote.
A well-known scientist (some say it was Bertrand Russell) once gave a
public lecture on astronomy. He described how the earth orbits around the
sun and how the sun, in turn, orbits around the centre of a vast collection
of stars called our galaxy.

At the end of the lecture, a little old lady at
the back of the room got up and said: "What you have told us is rubbish.
The world is really a flat plate supported on the back of a giant
tortoise."

The scientist gave a superior smile before replying, "What is
the tortoise standing on?"

"You're very clever, young man, very clever,"
said the old lady. "But it's turtles all the way down."

Well, it isn't turtles all the way down.

In a phrase, "A people acquire and retain well being in proportion to the knowledge they possess – and the use to which they put it."

404 error

09/01/04 | by david2 [mail] | Categories: General
From 404 error

The example of a 404 error is given as: http://www.whitehouse.gov/iraq/postwar-plan.ppt

disabling stop-a and ctrl-break on sparc

09/01/04 | by david2 [mail] | Categories: Geek
Three ways to do it:

1) Enter the following line in /etc/default/kbd (2.6 and up)
KEYBOARD_ABORT=disable

2) type the command: kbd -a disable (works for 2.6)

3) Enter the following line into /etc/system (2.4 and up)
set abort_enable = 0

and, if your hardware supports it:

4) turn your key to 'secure'. This overrides all software settings.

Jimmy Doohan says goodbye

08/31/04 | by david2 [mail] | Categories: General
Jimmy Doohan, Scotty from the original Star Trek series was at his last convention. He was recently diagnosed with Alzheimers and expects not to be attending any more.

From here

Just one indication of "Star Trek's" intersection with real life came at the convention on Saturday night, when the featured speaker at the banquet honoring Mr. Doohan was Neil Armstrong, the first human to walk on the moon.

Ending a talk full of "Star Trek" references, including a wish for a Federation starship for his next command, Mr. Armstrong addressed Mr. Doohan: "From one old engineer to another: thanks, mate."

How to transplant a Solaris disk from one platform to another

08/30/04 | by david2 [mail] | Categories: Geek
Say you've got a disk from a Sparc / Solaris machine, or a tape image of a disk, and it was originally running on one platform, and now you want to bring it up on another machine. How do you do it ?

This question gets asked (and answered) all the time in disaster recovery (DR) exercises. A classic situation will be this: a disaster occurs and computers are destroyed. The backup tapes with the images of each disk partition are at the DR site. They're taken out and now must be used to restore the necessary programs and data to a new system.

The trouble is that if the tapes were made from, say, a 3500 and now must be restored to a 450 (different hardware platforms), they won't simply run "out of the box". What steps need taking?

It's doable, and actually fairly simple at that. The strategy is to load an OS from CD onto the new system disks, and restore the rest from tape, making sure to preserve the platform-specific data. There is a specific set of directories that, if you copy them, will get you 85% of the way to having your image running on the new hardware.

So -- on a standard DR test, you would have 2 disks. The first disk would contain an OS loaded from CD. We'll call this disk 1. The 2nd disk will have the OS along with programs and data that need to be run on this hardware. So our strategy, then will be to copy the following directories from Disk 1 to Disk 2.

So here's what we do:

Mount disk2 to some convenient location, say, /mnt.
ex: If your target disk is c0t0d0s0, then :
mount /dev/dsk/c0t0d0s0 /mnt

From disk 2, remove the contents of the following directories:

(be sure to prefix each one with a "/mnt" if that's where you mounted disk2)

/dev/dsk
/dev/rdsk
/devices
/platform
/usr/platform
/kernel
/usr/kernel

You can do this by typing rm -rf /[source]/* where [source is one of the listings above.

ex: rm -rf /mnt/dev/dsk/* [enter]

Then -- copy the contents of these directories from disk1 to disk 2 using the following command :

cd [source] ; find . -depth | cpio -pvdum [target]

ex: cd /dev/dsk ; find . -depth | cpio -pvdum /mnt/dev/dsk [enter]

Complete these steps for all of the above directories.

Finally -- install your boot block in disk2:

installboot /usr/platform/`uname -i`/lib/fs/ufs/bootblk \
dev/rdsk/c0t0d0s0 [enter]

(assuming disk 2 is c0t0d0s0)

Finally, copy over your path_to_inst file:

cp /etc/path_to_inst /mnt/etc/path_to_inst

Now, halt your machine, and tell your openboot to boot from disk 2 and you'll be up in no time.

If you have fancy drivers, such as veritas, or ipfilter, you'll need to remove them and reinstall them because their drivers live in the different directories that we've replaced, and so they won't be complete.

RNC

08/29/04 | by david2 [mail] | Categories: General

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