Entries posted in February 2017

The past few days I've been doing more arduino-work. In between dying of sleep-exhaustion.

One thing that always annoyed me was that I had to hard-code my WiFi credentials in my projects, with code like this:

//
// Connect to the SCOTLAND network
//
WiFi.mode(WIFI_STA);
WiFi.hostname("tram-clock");
WiFi.begin("SCOTLAND", "highlander1");

//
// Attempt to connect - TODO: Timeout on failure
//
while (WiFi.status() != WL_CONNECTED)
    delay(500);

//
// Now we're connected show the local IP address.
//
lcd.print("WiFi connected  ");
lcd.print(WiFi.localIP());

Whilst looking at another project I found a great solution though. There is a library called WiFiManager which behaves perfectly:

• If you've stored connection details it will connect to the local WiFI network using those, automatically.
• If you've not saved previous connection details it will instead configure the device to work as an Access Point
  • You can then connect to that access point and see a list of local WiFi networks.
  • Choose the appropriate one from the list, enter your password, and these details are saved for the future.
  • The device will then reset, join the network via your saved choices and acquire an IP via DHCP as you'd expect.

The code for this is beautifully simple:

//
// Connect to WiFI with saved credentials, if any.
//
// Otherwise work as an access-point, named TRAM-TIMES, and
// let the user fill out their details.
//
WiFiManager wifiManager;
wifiManager.autoConnect("TRAM-TIMES");

This means my current project, which continues to revolve around tram-times, is so very much more user-friendly. It is a product you could package and take to a friends house, not a project you have to recompile to tweak.

For that reason, user-niceness, I reworked the on-board HTTP status-page to use bootstrap, be themed, and look nicer. Other than being housed in a horrid case the project actually looks like a product. Not one I'd buy, but neither one I'm ashamed of sharing.

Tags: arduino, esp8266 | No comments

Recently Vincent Bernat wrote about writing his own simple terminal, using vte. That was a fun read, as the sample code built really easily and was functional.

At the end of his post he said :

evilvte is quite customizable and can be lightweight. Consider it as a first alternative. Honestly, I don’t remember why I didn’t pick it.

That set me off looking at evilvte, and it was one of those rare projects which seems to be pretty stable, and also hasn't changed in any recent release of Debian GNU/Linux:

• lenny had 0.4.3-1.
• etch had nothing.
• squeeze had 0.4.6-1.
• wheezy has release 0.5.1-1.
• jessie has release 0.5.1-1.
• stretch has release 0.5.1-1.
• sid has release 0.5.1-1.

I wonder if it would be possible to easily generate a list of packages which have the same revision in multiple distributions? Anyway I had a look at the source, and unfortunately spotted that it didn't entirely handle clicking on hyperlinks terribly well. Clicking on a link would pretty much run:

 firefox '%s'

That meant there was an obvious security problem.

It is a great terminal though, and it just goes to show how short, simple, and readable such things can be. I enjoyed looking at the source, and furthermore enjoyed using it. Unfortunately due to a dependency issue it looks like this package will be removed from stretch.

Tags: security, vte | 2 comments

I've been tweaking my blog a little over the past few days, getting ready for a new release of the chronicle blog compiler (github).

During the course of that I rewrote all the posts to have 100% lower-case file-paths. Redirection-pages have been auto-generated for each page which was previously mixed-case, but unfortunately that will have meant that the RSS feed updated unnecessarily:

• If it used to contain:
  • https://example.com/Some_Page.html
• It would have been updated to contain
  • https://example.com/some_page.html

That triggered a lot of spamming, as the URLs would have shown up as being new/unread/distinct.

Tags: chronicle, meta | 3 comments

Like many people I use a password-manage to record logins to websites. I previously used a tool called pwsafe, but these days I switched to using pass.

Although I don't like the fact the meta-data is exposed the tool is very useful, and its integration with git is both simple and reliable.

Reading about the security issue that recently affected cloudflare made me consider rotating some passwords. Using git I figured I could look at the last update-time of my passwords. Indeed that was pretty simple:

git ls-tree -r --name-only HEAD | while read filename; do
  echo "$(git log -1 --format="%ad" -- $filename) $filename"
done

Of course that's not quite enough because we want it sorted, and to do that using the seconds-since-epoch is neater. All together I wrote this:

#!/bin/sh
#
# Show password age - should be useful for rotation - we first of all
# format the timestamp of every *.gpg file, as both unix+relative time,
# then we sort, and finally we output that sorted data - but we skip
# the first field which is the unix-epoch time.
#
( git ls-tree -r --name-only HEAD | grep '\.gpg$' | while read filename; do \
      echo "$(git log -1 --format="%at %ar" -- $filename) $filename" ; done ) \
        | sort | awk '{for (i=2; i<NF; i++) printf $i " "; print $NF}'

Not the cleanest script I've ever hacked together, but the output is nice:

 steve@ssh ~ $ cd ~/Repos/personal/pass/
 steve@ssh ~/Repos/personal/pass $ ./password-age | head -n 5
 1 year, 10 months ago GPG/root@localhost.gpg
 1 year, 10 months ago GPG/steve@steve.org.uk.OLD.gpg
 1 year, 10 months ago GPG/steve@steve.org.uk.NEW.gpg
 1 year, 10 months ago Git/git.steve.org.uk/root.gpg
 1 year, 10 months ago Git/git.steve.org.uk/skx.gpg

Now I need to pick the sites that are more than a year old and rotate credentials. Or delete accounts, as appropriate.

Tags: git, passwords | 4 comments