Category Archives: arch linux

Re-signing Openssh Certificates

Seldom do I get to write a post where I am offering information which might not actually be out there in a lot of places. I could not find this information on the web, and had to figure it out myself, by reading the code, and doing experiments.

I talked in the last post about the need to re-issue all the openssh certificates, in order to update the hash algorithm used for the signatures. My way of maintaining the certificates, in my repository, would make it easy for the signing box to get all the existing certificates, but not (directly) the public keys that are inside those certificates.

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SSH Certificate signing

I’ve encountered a problem migrating from Fedora to Arch which ends up being about ssh and openssh certificates. I look back and discover that I never posted anything about my movement toward openssh certificates. Curious because I wrote a lengthy document about it (because of my leaky brain – not because I am any kind of authority on it).

I will probably go back and write a post about it, and back date it. But now a problem has arisen. Rather than explain, let the boys at openssh speak for themselves, in the release notes for openssh 8.2:

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Percona Toolkit

This is to help me remember how to get percona toolkit, so that I can get the grants information out of the mysql database – the database in mysql which keeps tracks of users, databases, and (in particular) grants, i.e. permissions.

I originally dug this up for use when I was migrating tarragon. But now I am working on migrating oregano from fedora to arch, and I will have to transfer the databases. I have finally learned (I admit I am slow) that one cannot expect to be able to move the database directory even from one release to another, let alone from one distribution to another. The only way to do this properly is to dump the databases, reinstall mariadb/mysql in the new place, and set it up, and then reimport the dumped databases.

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Moving Oregano to arch

It is by no means certain that I will succeed with this effort, but I’m spending some time trying to get Oregano up on Arch.

The first step was just to get Arch booted up on oregano. My previous installation on a laptop didn’t involve an encrypted root, didn’t have raid arrays, didn’t have separate filesystems for things like /home and /var, didn’t run a web server, etc., so the first challenge is to get the system up with all that stuff.

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Forcing Monitor resolution

Cinnamon and Rosemary are now both happily rack-mounted in the basement (where it is cool, and where their many disk drives and fans can make as much racket as they wish).

Mostly I control them from the office with ssh and or vnc, but once in a while I need to actually be down there. My neighbor gave me a monitor, I have plenty of mice and keyboards, so I hooked up a KVM switch on the two of them so I didn’t have to keep getting behind the rack to move the monitor.

But alas, neither of them picked up the resolution of the monitor, I suppose (not sure) that with the KVM in the middle, they can’t really read the EDID and such stuff from the monitor. And since it is an “unknown” monitor, the display panel only shows 1024×768, 800×600 etc. The monitor itself helpfully tells me that it wants to be 1440×900 @60Hz.

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Setting up Arch on UEFI laptop

A good friend had mentioned to me that he used Arch linux in one of his recent installs. I’ve never tried it. I have this old HP laptop that a different friend gave me, when he replaced it. It isn’t that old! I decided to try installing Arch on it.

I had a bunch of issues, and ultimately today I resolved to reinstall the thing again, and record my experience. One of the issues – as usual a self-inflicted wound – is that this is a UEFI capable laptop, but the disk that is in it is MBR partitioned, not GUID partitioned. It probably would have been smarter to just partition the disk with a GUID table. But I didn’t. Below is the description of what I did.

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mdadm consistency checks

On ubuntu it seems there is an automatic mdadm array check provided in /etc/cron.d/mdadm, automatically installed with mdadm. This invokes a utility /usr/share/mdadm/checkarray and the cron is set to run this on the first Sunday of every month at 12:57am. And it is set to do this check on all arrays at one time.

This is horrible! So with 5 arrays, totalling 25TB, when this sucker fires up it quickly saturates the i/o capacity of cinnamon, slows to a crawl and settles in to run forever.

I’ve commented that out, and added my own /etc/cron.d/dee_mdadm which doesn’t do all the goofy shenanigans to try to ensure the thing runs on a Sunday (WHY?! Because the guy who wrote it doesn’t work on Sunday?). Instead, my version simply runs on the first of the month, at 12:57am, and on each month it starts the consistency check on a different array. I have 5 arrays, so 3 are checked twice a year, and 2 are checked thrice. Checking just one at a time means there is a good chance it will be done before morning, at least for the small arrays.

I don’t really think the whole consistency check idea is doing me much good, but at least this doesn’t unaccountably bring the system to its knees on the first Sunday of every month.

Update: December, 2021. I haven’t paid much attention to this, and today I found it happening again. I change the arrays around as needed, and hadn’t thought to go recheck what I had done, nor to ensure that the default didn’t reappear on an update, which it did.

For future reference, manually stopping a check:

echo idle > /sys/block/mdx/md/sync_action

or echo check to start manually.