II have a terrible time keeping this straight. This is a memory aid. I think it is correct, but it has been assembled from internet sources and not from reading the code, so this is not authoritative.
Category Archives: ubuntu
Certificates Redux
An earlier post talked about switching my server tarragon (where this blog sits) to a wildcard certificate from letsencrypt. There were two reasons why I was using a wildcard certificate. One had to do with test versions of websites that run on this server, and the need that some of those sites have for wildcards, of the form: bob.websitename.com, sally.websitename.com, etc. The other reason was that I have a lot of hosts (oregano, cinnamon, paprika, lemongrass) in addition to tarragon that “need” to have a certificate, for https, for imap, and for smtp, and when I was having to pay for them, it was cheaper to get one wildcard for wmbuck.net. Continue reading Certificates Redux
Dynamic DNS
I have used dynamic dns for around 20 years, I think. But I have always used dyndns.com which these days seems to want to call themselves dyn.com. And some years back they were bought by Oracle, the kiss of death, and now they are impossible to deal with, arrogant, unsupportive, insular – all the things I expect of Oracle.
And why have I kept using them? Because that is what the routers supported. Dyndns was there first, and the ubiquitous linksys and netgear routers usually have a feature to do automatic updates for dynamic dns, but (often) the router will only update dyndns: nobody else. And I’ve got routers installed in various people houses that are doing this.
But I recently added a new house that I support, and that person has a proprietary and ponderous comcast router, which will barely do anything useful, and has no facility to update dynamic dns.
LetsEncrypt Wildcard Certificates
Comodo is after me to renew, offering a free year. The last time I attempted to install a wildcard certificate from Lets Encrypt, shortly after they introduced the feature, I wasn’t able to figure it out. Now, 9 months later, there is a lot more information about how to do it. Before spending the money for a commercial cert, I thought I would give it a try.
I used the following on tarragon:
certbot certonly \
--server https://acme-v02.api.letsencrypt.org/directory \
--manual
-d wmbuck.net -d *.wmbuck.net \
--preferred-challenges dns
It is important that the server url by v02, because v01 servers can’t issue wildcard certs. I had to put TXT records in the DNS for them to verify, and they created the cert into the /etc/letsencrypt/live directory where all the others are.
This was trivially easy. Goodbye Comodo.
GDM fails to start
Experimenting with VMs on Ubuntu, I had the system running on a relatively small root disk. Was troubleshooting problems in the disk array, doing a lot of booting, and crashing, when suddenly the boot wouldn’t finish. Fortunately the boot wasn’t quiet and I could watch as it tried 20-30 times to start the gdm service.
I change the default to multi-user.target and got it up, and what do you know, the root filesystem is at 100%. Cleaned up some logs and crash logs and it came right up.
Interesting that it doesn’t have a way to at least alert you that is what its problem is.
Laptop backup and Lid events
I have some scripts which try to do backups on the laptop. It is a little more involved, since the laptop lid is closed most of the time, including at night. So the strategy is to have a cron job start periodically, determine if a backup had been done today and if not, attempt to do one.
Since the laptop could be in various locations, it tries to determine where it is – i.e. if it is in a known location (my house or my sister’s house, or one of my DC friends houses). If so, it can back up accordingly. This is done using SSIDs, which is adequate if not elegant.
One issue I’ve had is if the attempted backup starts right after the lid is opened, the wireless may not be ready yet, and so the backup may fail on account of no network. So I set out to try to figure out how to detect when the network is available, so the script can obtain that information. Continue reading Laptop backup and Lid events
Clamav and Amavisd
I find the whole clamav subsystem to be fragile. I think this is because it is written as a tool which stands on its own, but I’m only using it as a subsystem hung onto the side of amavisd. So there is some hand-waving and jiggery pokery with the sockets and the permissions to enable the two to communicate, which has to be done manually, and is not properly a part of either subsystem.
I have another article on setting up this subsystem here, which records some of the stuff being done. I think basically, amavisd has to know where the shared socket is, in order to send messages to clamav to check, and they have to agree on the ownership and permissions of the socket and its directory.
Once in a while that stuff gets crosswise, and since I only vaguely understood what was going on, and only did the hand-waving by rote, I got annoyed with it. I’ve grown used to being able to just have things slot in and work, without my having to actually dig in and understand them. The nerve of these people, to expect me to know what is going on in order to make it work! Irony intended. Continue reading Clamav and Amavisd
Recording last authentication
I wanted a way to be able to determine roughly how long it had been since a user had been active. I defined active to mean that the user had had to authenticate onto a system. This is so that a box on which the user had logged in has gone into screen lock, and the user has then authenticated again to the display manager.
I used the audit log of auditd to detect when a user has authenticated to a display manager. Auditd comes installed on Fedora, but I had to install it on the ubuntu boxes. Continue reading Recording last authentication
SVN Error E175002
I have been plagued by this error in subversion particularly when trying to commit from some of the boxes which I use less frequently:
svn: E175002: Unexpected HTTP status 200 ‘OK’ on ‘POST’ request to ‘/svn/!svn/me’
I have spent hours doing searches, reading posts, but have never found anyone whose issue was exactly like mine, not been able to figure it out based on other peoples issues. I resolved today to pay serious attention to figuring it out.
The solution turned out to be related to the url I used when I check something out of the svn repository. Long ago I set up a cname in dns for svn.wmbuck.net, and for a long time I used it. There is an apache config file for the servername svn.wmbuck.net, and it redirects http to https. Then at some point I began to just use https://wmbuck.net/svn/… to check things out. And that is where I went wrong, because that will work fine to do checkout, but when I try to commit from a box with that url (wmbuck.net) the http request is being routed to the default server, and the setup of the SSL session is failing.
I’m unsure exactly what is happening to cause the request to go to the default server. Perhaps the commit request does not specify SNI information.
What I do know is how to fix it. Do the checkout with https://svn.wmbuck.net/svn/
Running Apache under my username
I had some trouble on the development box with permissions and decided it would be “easy” to just have apache run under user dee, that would just make everything so much easier. Right.
Two things have come up so far, and more likely to follow. One, I had to change the ownership on /var/lib/php/session from apache to dee. Second, I had to add dee into tlsusers so the media stuff can read the certificate.
This may have been a bad idea.
1/31/18: Went back to using apache user, when I moved to Fedora 27. Fedora now uses php-fpm service, and now apache needs to open a socket to it, and it just became complicated.