Entries posted in December 2017

I've shuffled around all the repositories which are associated with the blogspam service, such that they're all in the same place and refer to each other correctly:

• https://github.com/BlogSpam-net/

Otherwise I've done a bit of tidying up on virtual machines, and I'm just about to drop the use of qpsmtpd for handling my email. I've used the (perl-based) qpsmtpd project for many years, and documented how my system works in a "book":

• https://book.mail-scanning.com/

I'll be switching to pure exim4-based setup later today, and we'll see what that does. So far today I've received over five thousand spam emails:

  steve@ssh /spam/today $ find . -type f | wc -l
  5731

Looking more closely though over half of these rejections are "dictionary attacks", so they're not SPAM I'd see if I dropped the qpsmtpd-layer. Here's a sample log entry (for a mail that was both rejected at SMTP-time by qpsmtpd and archived to disc in case of error):

   {"from":"<[email protected]>",
    "helo":"adrian-monk-v3.ics.uci.edu",
    "reason":"Mail for juha not accepted at steve.fi",
    "filename":"1512284907.P26574M119173Q0.ssh.steve.org.uk.steve.fi",
    "subject":"Viagra Professional. Beyond compare. Buy at our shop.",
    "ip":"2a00:6d40:60:814e::1",
    "message-id":"<[email protected]>",
    "recipient":"[email protected]",
    "host":"Unknown"}

I suspect that with procmail piping to crm114, and a beefed up spam-checking configuration for exim4 I'll not see a significant difference and I'll have removed something non-standard. For what it is worth over 75% of the remaining junk which was rejected at SMTP-time has been rejected via DNS-blacklists. So again exim4 will take care of that for me.

If it turns out that I'm getting inundated with junk-mail I'll revert this, but I suspect that it'll all be fine.

Tags: blogspam, exim4, github, mail-scanning, perl, qpsmtpd | 1 comment

So back in September I was talking about building a IoT Radio, and after that I switched to talking about tracking aircraft via software-defined radio. Perhaps time for a followup.

So my initial attempt at a IoT radio was designed with RDA5807M module. Frustratingly the damn thing was too small to solder easily! Once I did get it working though I found that either the specs lied to me, or I'd misunderstood them: It wouldn't drive headphones, and performance was poor. (Though amusingly the first time I got it working I managed to tune to Helsinki's rock-station, and the first thing I heard was Rammstein's Amerika.)

I made another attempt with an Si4703-based "evaluation board". This was a board which had most of the stuff wired in, so all you had to do was connect an MCU to it, and do the necessary software dancing. There was a headphone-socket for output, and no need to fiddle with the chip itself, it was all pretty neat.

Unfortunately the evaluation board was perfect for basic use, but not at all suitable for real use. The board did successfully output audio to a pair of headphones, but unfortunately it required the use of headphones, as the cable would be treated as an antenna. As soon as I fed the output of the headphone-jack to an op-amp to drive some speakers I was beset with the kind of noise that makes old people reminisce about how music was better back in their day.

So I'm now up to round 3. I have a TEA5767-based project in the works, which should hopefully resolve my problems:

• There are explicit output and aerial connections.
• I know I'll need an amplifier.
• The hardware is easy to control via arduino/esp8266 MCUs.
  • Numerous well-documented projects exist using this chip.

The only downside I can see is that I have to use the op-amp for volume control too - the TEA5767-chip allows you to mute/unmute via software but doesn't allow you to set the volume. Probably for the best.

In unrelated news I've got some e-paper which is ESP8266/arduino controlled. I have no killer-app for it, but it's pretty great. I should write that up sometime.

Tags: esp8266, radio | No comments

I've now been living in Finland for two years, and I'm pondering a small project to translate my main website into Finnish.

Obviously if my content is solely Finnish it will become of little interest to the world - if my vanity lets me even pretend it is useful at the moment!

The traditional way to do this, with Apache, is to render pages in multiple languages and let the client(s) request their preferred version with Accept-Language:. Though it seems that many clients are terrible at this, and the whole approach is a mess. Pretending it works though we render pages such as:

index.html
index.en.html
index.fi.html

Then "magic happens", such that the right content is served. I can then do extra-things, like add links to "English" or "Finnish" in the header/footers to let users choose.

Unfortunately I have an immediate problem! I host a bunch of websites on a single machine and I don't want to allow a single site compromise to affect other sites. To do that I run each website under its own Unix user. For example I have the website "steve.fi" running as the "s-fi" user, and my blog runs as "s-blog", or "s-blogfi":

root@www ~ # psx -ef | egrep '(s-blog|s-fi)'
s-blogfi /usr/sbin/lighttpd -f /srv/blog.steve.fi/lighttpd.conf -D
s-blog   /usr/sbin/lighttpd -f /srv/blog.steve.org.uk/lighttpd.conf -D
s-fi     /usr/sbin/lighttpd -f /srv/steve.fi/lighttpd.conf -D

There you can see the Unix user, and the per-user instance of lighttpd which hosts the website. Each instance binds to a high-port on localhost, and I have a reverse proxy listening on the public IP address to route incoming connections to the appropriate back-end instance.

I used to use thttpd but switched to lighttpd to allow CGI scripts to be used - some of my sites are slightly/mostly dynamic.

Unfortunately lighttpd doesn't support multiviews without some Lua hacks which will require rewriting - as the supplied example only handles Accept rather than the language-header I want.

It seems my simplest solution is to switch from having lighttpd on the back-end to running apache2 instead, but I've not yet decided which way to jump.

Food for thought, anyway.

hyvää joulua!

Tags: apache, lighttpd, multiviews | 2 comments