Archive for the ‘Trial and Error’ Category

Apr
29
2017

Fix Autofs on Raspberry Pi 3

Doesn’t work, but autofs works on all other machines just fine.

http://www.linuxquestions.org/questions/linux-general-1/automount-fails-with-key-xxxx-not-found-in-map-source-s-4175514301/

“showmount” works fine.

https://www.centos.org/forums/viewtopic.php?t=45056

mentioned resolv.conf. Found a strange entry there:
domain hsd1.co.comcast.net

no other machines have that entry. How to remove?

https://askubuntu.com/questions/755297/resolveconf-u-keeps-adding-an-unwanted-search-domain-to-resolve-conf

Didn’t work.

Maybe change /etc/dhcpcd.conf to not request the domain name?

That removed the domain from resolv.conf, but autofs still fails.

Manually running sudo mount bruce:/ /mnt/bruce/ works, so it’s not NFS sucking. definitely autofs.

> mount |grep bruce
bruce:/ on /mnt/bruce type nfs4 (rw,relatime,vers=4.0,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=192.168.1.106,local_lock=none,addr=192.168.1.102)

maybe I need to uncomment the NFS4 line in /etc/auto.net? I’ve never done that anywhere else…no effect

This worked…no idea why: http://russell.ballestrini.net/autofs-net-automount-stopped-working/

I’ll try rolling back my other changes to see if they’re necessary too. Nope, only the change to /etc/auto.master

Posted in Linux, Trial and Error | Comments Off on Fix Autofs on Raspberry Pi 3

Nov
23
2016

Getting started with MQTT

At this point, I have a few IOT things on my home network. The first were a couple of EcoPlugs Wifi outlets that I use to control my gutter heaters in the winter, and the next was a custom garage door controller. For the former, I’m basically controlling them by using a replay attack (I hope to make a post about this soon)…re-sending packets that I observed the EcoPlugs app sending. For the latter, I’m using a custom http interface. Since both of these contain an ESP8266, I’d like re-program them and unify them both to use the MQTT protocol.

While browsing Hackaday, I came across their Minimal MQTT series. In this post, I’ll begin by walking through that series, noting my thoughts, then conclude by getting things set up the way I want.
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Posted in ESP8266, How To, IOT, Linux, Trial and Error | Comments Off on Getting started with MQTT

Nov
19
2016

Issues upgrading from Ubuntu 15.10 to 16.10 (via 16.04)

Canonical recently dropped official support for Ubuntu 15.10 “Wily Werewolf”, so I decided to upgrade. I also don’t like being stuck on Long-Term-Support releases, so I did 2 upgrades in sequence: 15.10 “Wily Werewolf” to 16.04 “Xenial Xerus” to 16.10 “Yakkety Yak”. In the past, I’ve just done a clean install, but the trouble with that is having to re-do all my various customizations. This time I figured I’d just try an in-place upgrade. Of course, this meant that my customizations conflicted with packages changes. I’m still not sure which method is better.

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May
12
2016

MAX7219 Seven-segment driver

img_20160914_200614010

I have a couple projects in mind where I want to use a seven-segment display (one of them where I want large digits), but I don’t want to dedicate too many pins to driving the display. Also, writing custom code to multiplex the digits seemed tedious.

I read about the MAX7219 chip, which lets you drive up to 8 digits over SPI, and it seemed to be just what I was looking for.

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Posted in How To, Trial and Error | Comments Off on MAX7219 Seven-segment driver

Apr
11
2016

Better sslh

For those that don’t know, sslh is a TCP port multiplexer. This basically means that you can serve both https and ssh traffic from the same port. It’s most useful for circumventing corporate firewalls that block TCP port 22 (i.e. ssh), but allow TCP port 443 (i.e. https) by serving both on TCP port 443.

In the default configuration, however, all connections that go through sslh look to ssh or apache as if they came from localhost. This isn’t ideal if you want to run something like denyhosts or fail2ban to block malicious ssh login attempts.

sslh does have an option to do “transparent” proxying so ssh and apache think that the connections have come from the right place. In this post, I’ll describe how I set this up on my machine.

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Posted in How To, Linux, Trial and Error | 1 Comment »