Category Archives: ubuntu

Switching to systemd-networkd

Since moving to IPv6 I have had two recurrent problem: one with some conflict between systemd and the kernel over the /proc/sys/net/ipv6/conf/*/accept_ra, and the second with losing the static ipv6 address assignments on some boxes. I believe the former problem to have something to do with systemd wanting to have control of the sysctl variables, such as accept_ra.

The latter problem is due to the various bits of software that want to have a say in the control of the network. In part some of this is my own fault, as I do have these various bits installed – and if they weren’t installed they could not be causing trouble.

I installed NetworkManager in some places, even when it hadn’t been installed by default, because I wanted to be able to control things with the network applet in gnome. I installed dhclient even though it wasn’t installed, because I wanted better ability to see and control the dhcpv6 leases, particularly the DUID, and network manager made that difficult (and astonishingly, in some cases simply didn’t work).

Continue reading Switching to systemd-networkd

IPv6 Re-implementation

This is a follow up to the activities in IPv6 implementation, which was published on March 2nd and revised up through March 19th, as new challenges were addressed. Since March 19th a great deal of what I wrote has been revised, as I have learned a lot more.

The main issue was that there remained a number of problems with the implementation of IPv6 in my residence.

  • The biggest was the question how to handle the delegated prefix, particularly in renumbering. Over the course of the last several months I have to note that Comcast has never changed my prefix, except early on, when I forced it to do so by changing my DUID. And I don’t think it likely that my prefix would change unless some great catastrophe befalls which results in my being down for a very extended period – like 30 days; or more likely there is some change in my service (a change in ISP, or perhaps fiber arriving in my area).
  • The first implementation required that I make patches to the code of my router. This meant that I would have to figure out how to carry those patches forward in the event of firmware updates from Ubiquiti, the maker of the Edgerouter-X that I am using.
  • The implementation was pretty fragile, with a lot of unrelated bits in different places. In particular there was a lot of hand-waving in trying to assign and maintain a separate network for the virtual machines on one of the interior boxes.
Continue reading IPv6 Re-implementation

Waiting for networks

I was revising some things in my startup scripts. I have a sort of generalized startup script in all the boxes in my constellation, which is capable of doing 8 or 10 different things that various of the boxes need to do at startup.

For example, the various gateway boxes need to open up (auto)ssh connections to my house with reverse tunnels so I can reach them. On some boxes I want them to open a vncserver so I can get a graphical environment up. On some others they may need to mount some filesystems, with smb or nfs. On some of them I want them to figure out where their router is, in case I want to open up their router in a browser. On some I need them to establish the keychain.

Continue reading Waiting for networks

IPv6 implementation

This post describes my first attempt at implementation of IPv6, a process that took place over a span of a couple of months. After this was done, and was working, a “better way” emerged, which will be the subject of an additional post. I leave this in here for the sake of documenting what I did the first time, but in the unlikely event that anyone finds this while looking on the net for information about implementing a similar arrangement, I urge you to find the other post, and read it as well. This implementation was fragile.

A few weeks back (10 Feb) my friend Mr. G and I exchanged an email in which he said of a possible project “…but this would be an opportunity to learn IPv6”, reminding me that I have for a long time wanted to learn more about IPv6. Part of the genesis of that email conversation was a recent switch by my brother-in-law to a new ISP that employed CGN, so called Carrier Grade Nat, which had disrupted arrangements I had in place for reaching my brother-in-law’s home network. Mr G. opined that the move towards CGN, and other things the ISPs were doing, raised the specter that someday, perhaps sooner than we expect, anyone desiring to do more with their network than occasionally use a browser would find ourselves having to move to ipv6.

More, I have actually wanted to use IPv6 for a long while, but had been under the impression (erroneously) that Comcast really wasn’t ready for this, that all they would give me was a 6to4 tunnel, which I barely understood anyway.

Continue reading IPv6 implementation

Rosemary Recovery 2020

There was a fail event reported on rosemary from one side of a pair of 60GB SSDs, which hold Rosemary_Data. Typical of my installations this mirror set holds the stuff the system needs beyond the os install: /home, databases, certificates, repositories, mail, samba, local bin, etc. Its a mirror set with an encrypted container, containing a btrfs filesystem. The older versions of these setups contain separate btrfs subvolumes for the different directories, newer ones have only one subvolume for that, and another for snaps. This is an old one.

Rosemary doesn’t have an extensive set of services – really only the /home and the databases. No real need for much of anything else. The local bin comes out of the repo anyway, there is no mail, no repository, no certs. However, without that volume the system won’t come up in a usable way. So lesson one learned here was when you get a fail event, attend to it. I let it go for a few days, because I knew I was going to have to pull the case out of the rack mount to get at the SSDs.

Continue reading Rosemary Recovery 2020

Stop pulseaudio startup under gdm

GDM is the display manager I’m using under Arch. I think it is the default DM in Arch, but I don’t really remember if I’ve changed it. In any case, the issue that has arisen is that when GDM is started by systemd after a reboot, it is launched with its own pulseaudio daemon. Then when I log in, as dee, I get a second pulseaudio daemon for dee (which is actually the desired one).

Most of the time this doesn’t matter, I guess. But I’m interested in enabling network sources in pulseaudio so I can (perhaps) have the boxes in the basement send their sound upstairs to oregano. Right now avahi is broadcasting two different network sound services on oregano, one from dee and one from gdm.

I want to stop pulseaudio from launching under gdm.

I thought this would be a simple matter of turning off autospawn in the client conf. The client conf is located in ~/.config/pulse (I think it used to be in ~/.pulse and was moved to be more “correct”). And ~ for gdm is /var/lib/gdm, so I tried client.conf in both .config/pulse/client.conf and .pulse/client.conf, but neither worked.

Poked around a little more and discovered that /usr/lib/systemd/user has a pulseaudio.service and pulseaudio.socket so these are actually being launched there by systemd. After a little reading I found that one could mask them by creating a local user override in ~/.config/systemd (for gdm this is /var/lib/gdm/.config/systemd), so I put in a /var/lib/gdm/.config/systemd/user/pulseaudio.socket and symlinked it to /dev/null.

And when I rebooted, sure enough I got not pulseaudio daemon for gdm.

Installing Mac OS on KVM

Background

I first tried to install Mac OS onto a VM back in 2010 or 2011 I think. I’ve come back to the task from time to time and have never been successful, but truthfully until recently all the virtual machines I’ve created on Cinnamon had been too slow to be useful anyway. Now that I have Cinnamon doing virtual machines well, I came back to the Mac – at the same time I was doing other VMs, and I didn’t keep careful track of what I did to get it up. This document is meant to record what I remember of what I did the first time, and then to do it again and keep better records.

Continue reading Installing Mac OS on KVM

Packagekit adjustments in ubuntu

When I tried to upgrade Cinnamon to Focal, I began to experience a lot of odd problems with VNC and GDM and the whole collection of machinery associated with getting a graphical environment particularly in a remote window. Cinnamon is physically downstairs in a rack in the basement, and my usual way of working is 80-90% ssh/command line and occasionally vinagre in an adjacent monitor with screens for a dozen or so places that I occasionally need to see graphically, including Cinnamon, but Vinagre usually stays pointed at Rosemary (also in the basement).

Continue reading Packagekit adjustments in ubuntu

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.

Continue reading Re-signing Openssh Certificates

Memory on the Gateway Pi

I now have 8 of these gateway boxes out there. This morning as I was checking backups on one of them, I observed that it took quite a long time to respond. I ran a top on it and was horrified to see that its memory use was 100% and so was its swap. Holy @#$%!@ Batman!

Most of the memory was being used by the lxpanel. And (hangs head in embarrassment) there were actually two lxpanels running – one for the console and one in the vnc window I launch at startup.

It seems the lxpanels leak. I don’t know how badly, but it doesn’t matter. These boxes are meant to run forever so even a tiny leak is eventually fatal.

Well this was simple. I will seldom, if ever, need to get into a graphical environment remotely, and if I do I can always start vnc from the command line. So I took out the startvnc from the startup script. And I have even LESS need for a graphical console since there is not even a monitor on these things. So I set the default systemd target to multi-user.target.

Did this on all the gateways that are running on pi-zeros. Those few running on bigger ubuntu boxes I didn’t really have the problem anyway.

After rebooting them they come up with no lxpanels. I’ll watch the memory use, but I think this will fix the problem.