Presentation on Slackware package management
#35 Henry, Thursday, 07 January 2010 11:28 PM (Category: Linux)
(Tags: slackware twuug)

I gave a presentation on Slackware package management at the TWUUG meeting tonight. Everything I know about the topic, I learnt at the December TWUUG meeting, and now it's my turn to pay back. I've already described in this blog a lot of what I have learnt. I did a small HTML presentation, and I will expand on it shortly.

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Mac Mini hardware fix coming
#33 Henry, Wednesday, 06 January 2010 10:42 AM (Category: Hardware)
(Tags: macmini)

A year and a half ago, I bought a used Intel Mac Mini. I bought memory from Other World Computing to max out the memory in the Mac Mini. While installing the memory, I snapped a little wire off. There is a temperature sensor above the CPU and it connects to the motherboard. You have to disconnect this to open up the Mac Mini to get at the memory. The connector is a tiny thing, a flimsy thing, and one wire snapped off. I could have continued to run the Mac Mini, but the fan would have run non-stop and the Mac Mini would no longer be a silent computer. I put it aside.

I searched the Apple website and went round and round in loops trying to find where you could buy parts. I went to the local Apple store and when I started talking about opening the Mac Mini and breaking a wire, they backed away from me and said they don't do that sort of thing and they can't help me and I should phone Apple, as long as I have Apple Care on the Mac Mini. I don't, so I didn't bother phoning Apple.

I searched for replacement parts, but not diligently. Every now and then I would get enthusiastic and attempt to fix it myself. I even bought soldering gear late last year. Now, a year and a half later and the Mac Mini is going to waste, and it's the first week of a new year and I better do something about this. I pulled it out, got my soldering gear ready, and found that in the last year and a half, my eyes have deteriorated more. I can no longer see the damn connectors and wires. I have one of those Third Hand devices with a magnifying glass, but even that was difficult to use. After shortening the broken wire by an inch trying to remove the plastic sheath, I gave up.

I googled for the problem. It took about half an hour of refining my search terms before I found results pertaining to my situation. I found a discussion about breaking the wires which pointed to a source for a replacement - MacPro.com. I ordered the part, it cost $45 including shipping, and it's already on its way here. I hope to be able to get this Mac Mini working again very soon. I regret not finding this replacement part a year and a half ago when I broke it.

Then I found this discussion about the broken wire with a good photo of the problem and suggesting that you could get replacement parts from Apple. Now why didn't I think of that - getting the replacement part from the manufacturer. I would still like to know how you get to Apple to order parts.

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Tricky Slackware update
#32 Henry, Wednesday, 06 January 2010 10:15 AM (Category: Linux)
(Tags: slackware)

I check my Slackware installations once a week to see if there are any updates. Yesterday, there were several. The Gnu compiler had an upgrade, glibc and the kernel. There was a warning that libata had changed and finally all vestiges of calling hard disks hda, hdb, etc was gone, and all hard disks would be sda, sdb, etc. A warning was issued to change /etc/fstab and /etc/lilo.conf before hand. All but one of my servers and desktops were already over on the sda pattern, and nothing needed to be done. My home server is a little older and it still had a hda. This one gave me some grief.

I changed /etc/fstab as directed, but "forgot" to change lilo.conf and that started a problem. When I rebooted, it couldn't mount root, and the boot failed. I booted from the Slackware cdrom, and got to the command line and had access to lilo.conf but I had a problem. Booting from the original Slackware 13 cdrom had me viewing the hard disk as hda. But if I booted from the hard disk, it was seen as sda. My problem was because I had a faulty understanding of lilo. I researched for a while, corrected my understanding and fixed the problem.

I booted from the Slackware 13 cdrom and got to the command line. I mounted the hard disk:

mount /dev/hda1 /mnt

Changed down to /mnt/etc and edited lilo.conf. There are two sections affected - boot= and root=. The line

boot=hda

refers to where to install the lilo data NOW, so this had to be set to hda because that was where the hard disk was right now. The line

root=hda1

refers to where to find root after booting. After booting, this would be sda1, so the line should be

root=sda1

I changed that and saved the file, then ran lilo (requiring a little more research)

/mnt/sbin/lilo -r /mnt

Then I rebooted, and it all started correctly. I changed lilo.conf again, because now the hard disk is seen as sda, so the boot line had to change to

boot=sda

I saved it and booted again, and the problem was over. I learnt some things. Mostly, I need to follow instructions better. But because I didn't, I now have a better knowledge of lilo's behaviour and configuration. And the home server is back in operation and all is well.

Addendum: I have found another server with the same hda issue. This time I remembered to change lilo and run it. I changed the root= line, ran lilo and it rejected it with "Fatal: Illegal 'root=' specification: /dev/sdb1". I experimented with this and found the answer. I booted from the Slackware install disk, mounted the drive and edited lilo.conf. When I ran lilo again, it worked. I think the difference is this: if you are editing lilo.conf on the disk you booted from, it checks the root= line and will reject it if it is not found. If you boot from another disk, like the Slackware installation DVD or CDROM, and run lilo, it does not check the root= line. Something like that. It worked, I got my system upgraded, and I know how to get around the problem next time.

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SpamAssassin issue resolved
#31 Henry, Sunday, 03 January 2010 1:07 AM (Category: Email)
(Tags: spamassassin)

I searched online for the SpamAssassin problem I was having. I was not alone. There is a date test that looks for dates "grossly in the future" and triggers if the date is past 2010. This started being triggered on all emails once 1st January 2010 came along, and added about 3 points to the spam score. This was enough to tip a couple of emails over my threshold and turn them into false positives.

Here's the rule that was causing the problem:

FH_DATE_PAST_20XX: Date =~ /20[1-9][0-9]/

and the description is:

The date is grossly in the future.

There are two suggestions to fix the problem. First, turn the test off by adding this line to /etc/mail/spamassassin/local.cf:

score FH_DATE_PAST_20XX 0.0

Or push the problem ten years into the future by changing the file /usr/share/spamassassin/72_active.cf so that the rule is now:

Date =~ /20[2-9][0-9]/

SpamAssassin conducts a whole range of date tests, and this is just one of them. I looked through my test batch of spam and realised what it is trying to achieve. One trick that spammers use is to set the date of the spam email way in the future, so when you view your email (usually in reverse chronological order), that spam email is always jammed at the top and in your face because it's set to 2030 or 2050 or something. This test helps eliminate those gross abuses, so I can see that it is a useful test to have and I would rather not do without it.

Therefore I opted to use the second solution and still look for grossly in the future dates, which now means anything past 2020.

To make the change take effect, I restarted SpamAssassin with:

/etc/rc.d/rc.spamassassin restart

That's specific to Slackware. Other distributions will differ.

The only emails affected were ones that Anne sent from iPhoto to herself locally. They were the only false positives, and she has already worked around the problem by using a description and not just the filename.

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Time Capsule is live
#30 Henry, Saturday, 02 January 2010 11:18 PM (Category: Apple)
(Tags: wifi apple)

It was time to get the Time Capsule live.

I turned off the D-Link WAP I've been using for years. I made space for the Time Capsule, plugged it in, started the Airport Utility and was faced with options. I sighed at first, because this is usually confusing where the vendor uses terms that don't mean much. But I was surprised by Apple's approach. It was common sense, didn't introduce new jargon and led me very simply through it. The questions were easy and worked. The one thing I was worried about was DHCP. I did not want the Time Capsule to handle DHCP. I do that myself elsewhere. They asked if I wanted that, indicating they would set up the Time Capsule as a bridge. That worked. It saved its configuration several times, and then it was live.

I got my iPod Touch working with it. Easy. Got the two Tivos working with it. Easy. Got the MacBook working with it. Easy. Got the two Mac Minis working with it. Also easy. Then I ran into a problem with the Airport Express.

I use the Airport Express to hook into my stereo. I use the Remote app on my iPod Touch to control iTunes on my Mac Mini, and push the music out to the Airport Express. The system works really nicely. I had set up a nice playlist for New Years Eve and played great background music all night, and that was just a few days ago, so I knew it was working. But now the Airport Express would not connect to the Time Capsule. I eventually figured it out. I pulled the Airport Express out of the stereo, brought it into the computer room, and hooked it to the network with an Ethernet cable. Then the Airport Utility saw it, and I could reconfigure the wireless network in it. Unplugged it, took it back to the stereo and reconnected it, and it fired up and everything is working nicely.

So it's done. My wireless network has gone from 802.11g to 802.11n. I can already notice the laptop speed increase.

And I set up my MacBook to backup (Time Machine) to the Time Capsule. (Don't you just loathe all the cutesy names - Time Machine, Time Capsule, Airport Express, Airport Extreme.)

One more step towards Apple domination in the house.

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