If you want to play with HDMI signals or just emulate a connected display for whatever reason, you need to fool your videocard to think something is really connected.
Continue reading Emulating HDMI connectionAll posts by danman
Enable system site packages in virtualenv
I started using virtualenv for all python apps I run (because I hate to make mess with pip in system site-packages). Later I’ve found out that some dependencies can not be installed via pip but are included in standard system packages installed via apt or yum. To use these imports inside your venv, you need to specify parameter –system-site-packages when creating your venv. If you only find out that you really need them later, you can enable them by deleting following file:
your_venv_dir/lib/pythonXXX/no-global-site-packages.txt
Happy pythoning!
Source: https://virtualenv.pypa.io/en/latest/userguide/#the-system-site-packages-option
My unbiased experience with JLCPCB
I needed to fabricate some PCBs. I’ve seen some youtubers to advertise and recommend this service so I decided to give it a try. My order was done without using any affiliation link or discount code so there was no way for them to know who I am. I needed to create a microSD breakout board and luckily I found a similar OSHw project and only made some modifications: https://github.com/danielkucera/MicroSD_Sniffer . I prepared my board in Eagle and generated gerber files. Continue reading My unbiased experience with JLCPCB
Automatic letsencrypt wildcard cert renewal with nsupdate
I’m using a wildcard cert from letsencrypt. Currently there is only one way how to verify that you hold the domain you are requesting cert for: creating TXT record in that domain. You can do it by hand when asked by certbot but you don’t want to do this each 90 days. If you are running your own DNS servers with PowerDNS like me there’s an elegant solution: RFC2136. This allows you to update your zones without writing config files and restarting anything.
Continue reading Automatic letsencrypt wildcard cert renewal with nsupdate
My git cheatsheet
Show git log as tree
$ git log --oneline --graph --decorate --all | * 0255f78c (HEAD -> qmtech, my/qmtech) added support for qm_xc6slx16_sdram board | * dae037cf (my/spisingle, spisingle) added spi 1-bit mode, code from litex |/ * 1325aff6 (origin/master, origin/HEAD, master) correctly use result of Record.connect in Converter (#81)
Rebasing
git rebase --onto <where-to> <where-from> <what>
$ git rebase --onto master spisingle qmtech First, rewinding head to replay your work on top of it... Applying: added support for qm_xc6slx16_sdram board $ git log --oneline --graph --decorate --all * 37d2eff0 (HEAD -> qmtech) added support for qm_xc6slx16_sdram board | * 0255f78c (my/qmtech) added support for qm_xc6slx16_sdram board | * dae037cf (my/spisingle, spisingle) added spi 1-bit mode, code from litex |/ * 1325aff6 (origin/master, origin/HEAD, master) correctly use result of Record.connect in Converter (#81)
Push changed branch
$ git push my qmtech -f Counting objects: 7, done. Delta compression using up to 12 threads. Compressing objects: 100% (7/7), done. Writing objects: 100% (7/7), 1.86 KiB | 1.86 MiB/s, done. Total 7 (delta 5), reused 0 (delta 0) remote: Resolving deltas: 100% (5/5), completed with 5 local objects. To https://github.com/danielkucera/misoc.git + 0255f78c...37d2eff0 qmtech -> qmtech (forced update) $ git log --oneline --graph --decorate --all * 37d2eff0 (HEAD -> qmtech, my/qmtech) added support for qm_xc6slx16_sdram board | * dae037cf (my/spisingle, spisingle) added spi 1-bit mode, code from litex |/ * 1325aff6 (origin/master, origin/HEAD, master) correctly use result of Record.connect in Converter (#81)
Set default github username
$ git config --global credential.https://github.com.username danielkucera
Squash commits
git rebase -i <after-this-commit>
replace “pick” on the second and subsequent commits with “squash” or “fixup”
Ignore line endings
git config --global core.autocrlf true
E-mail to SMS
If you are dealing with network monitoring, you might consider using SMSes because they are completely independent. On the other hand, many monitoring systems don’t support HTTP calls (which is the usual way for sending them) but most of them support sending e-mails. Here I want to describe how to configure your server to receive e-mails and transform them to SMSes. Continue reading E-mail to SMS
FL2000 as signal generator
First we need to generate some samples: Continue reading FL2000 as signal generator
FM transmission test with FL2000
My USB 3.0 to VGA adapter arrived a few days ago so I tested the FM transmission example. Continue reading FM transmission test with FL2000
Smart energy meter
In my current flat the central heating runs on natural gas and I wanted to have a nice chart showing its consumption. The gas meter is directly in the hallway so everyone can see it. Because of this, I cannot simply bring in AC power and attach some exposed wires, otherwise my neighbors would probably call anti-terrorist group. The measuring device has to be small, look professional and have low power consumption so it can run on batteries. In next lines I’ll describe how I have achieved this.
Getting root access on ZyXEL VMG1312-B30B
Nothing special, just use undocumented command sh and you are there (I found it out by a mistake):
danman@silverhorse:~$ nmap 10.0.0.138 Starting Nmap 7.60 ( https://nmap.org ) at 2018-03-26 22:54 CEST Nmap scan report for 10.0.0.138 Host is up (0.013s latency). Not shown: 996 closed ports PORT STATE SERVICE 21/tcp open ftp 22/tcp open ssh 23/tcp open telnet 80/tcp open http Nmap done: 1 IP address (1 host up) scanned in 3.14 seconds danman@silverhorse:~$ telnet 10.0.0.138 Trying 10.0.0.138... Connected to 10.0.0.138. Escape character is '^]'. ZyXEL VDSL Router Login: admin Password: admin > help ? help logout exit quit reboot adsl xdslctl xtm brctl cat loglevel logdest virtualserver ddns df dumpcfg dumpmdm meminfo psp kill dumpsysinfo dnsproxy syslog echo ifconfig ping ps pwd sntp snmp sysinfo tftp wlctl arp defaultgateway dhcpserver dhcpcondserv dns lan lanhosts passwd ppp restoredefault route save swversion uptime cfgupdate swupdate exitOnIdle wan rip igmp wlan telnetd natp sysstate sipalgctl celld autoexec fileShare igmp btt ledctl > sh shell Password: admin ~ # ls bin etc linuxrc proc tmp vmlinux.lz data firmware mnt sbin usr webs dev lib opt sys var