All posts by danman

Linux, Projects

Fixing non-working WiFi on RT5350

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I have a favorite cheap chinese router based on RT5350 (running OpenWRT).

img_20160324_121441

Recently, I was wondering, why I can’t get WiFi on a few of them working. I have one piece running quite old (4xxx svn) OpenWRT where the WiFi works OK. So I tried to compile exactly the same version and install it on the non working piece. I also put the same wifi config there but nothing. It didn’t work. Continue reading Fixing non-working WiFi on RT5350 →

Linux

amavisd-new: disable e-mail filtering per destination domain

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Testing SPAM filtering from shell

echo "XJS*C4JDBQADN1.NSBN3*2IDNEN*GTUBE-STANDARD-ANTI-UBE-TEST-EMAIL*C.34X" | mail -s Spam_test danman@example.com

Disable filtering for example.com

add following lines to /etc/amavis/conf.d/50-user (don’t forget the dot before domain, it has to be there):

@bypass_spam_checks_maps = (
[".example.com"],
);

@spam_lovers_maps = (
[".example.com"],
);
Linux

Using socat for multicast receiving and proxying

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socat is a very handy networking tool. Here are some examples for multicast manipulation

Receive multicast data to stdout or file

If you save common mpeg-ts IPTV multicast this way, you can play it with any decent player, like vlc or mplayer.

SRC=239.1.2.3;SRCP=1234;IF=eth0

socat -T 3 UDP4-RECV:$SRCP,bind=$SRC,ip-add-membership=$SRC:$IF,reuseaddr -

socat -T 3 UDP4-RECV:$SRCP,bind=$SRC,ip-add-membership=$SRC:$IF,reuseaddr - > stream.ts

Create high-available multicast proxy

socat relays packets from 239.1.1.1:1234 to 239.2.1.1:1234 with multicast ttl=8.
If no packet arrives in 3 seconds (-T 3), socat exits and script runs another socat which joins another multicast 239.1.1.2:1234 and continues with relaying. You can add as many sources as you want, they will be used in a round-robin fashion. If you want to switch to next source, just kill currently running socat.

DST=239.2.1.1:1234
while true
do
 SRC=239.1.1.1;SRCP=1234;IF=eth0
 socat -T 3 UDP4-RECV:$SRCP,bind=$SRC,ip-add-membership=$SRC:$IF,reuseaddr UDP4-SENDTO:$DST,ip-multicast-ttl=8
 SRC=239.1.1.2;SRCP=1234;IF=eth0
 socat -T 3 UDP4-RECV:$SRCP,bind=$SRC,ip-add-membership=$SRC:$IF,reuseaddr UDP4-SENDTO:$DST,ip-multicast-ttl=8
 ...
done
Linux

Fixing distorted audio with Intel HDA on Ubuntu

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edit /etc/pulse/default.pa
before:

### Automatically load driver modules depending on the hardware available
.ifexists module-udev-detect.so
load-module module-udev-detect
.else
### Use the static hardware detection module (for systems that lack udev support)
load-module module-detect
.endif

after:

### Automatically load driver modules depending on the hardware available
#.ifexists module-udev-detect.so
#load-module module-udev-detect tsched=0
#.else
### Use the static hardware detection module (for systems that lack udev support)
load-module module-detect
#.endif

Restart pulseaudio or the whole system.