Why does(n't) it work?

Getting rid of TWSI lines in conceptronic SNAS' dmesg

1 minute read Modified: 11 Aug, 2018

The problem

When I was looking at the dmesg of a Conceptronic CH3SNAS (this is similar to a DS-323), I saw the following lines filled the dmesg.

TWSI: mvTwsiStartBitSet ERROR - Start Clear bit TimeOut .
TWSI: mvTwsiStopBitSet ERROR - Stop bit TimeOut .

I’m using fun_plug on the system to be able to do more with it, but this is also the reason the lines appear in dmesg.

A little search provide me with a forum post which explains how to get rid of these messages.

tinc: Network is unreachable

1 minute read Modified: 10 Aug, 2018

The problem

When the Fedora 20 server at my parents rebooted because of a general power failure, the tinc tunnel between my parents and myself didn’t work anymore.

Troubleshooting

I enabled the debug logging by sending an INT signal to the daemon.

tincd -n ubbink -k INT

This resulted in the following log items (journalctl -f -l –unit tincd@ubbink.service):

tinc.ubbink[9707]: Got INT signal
tinc.ubbink[9707]: Temporarily setting debug level to 5.  Kill me with SIGINT again to go back to level 0.
tinc.ubbink[9707]: Trying to connect to amys (xxx.xxx.xxx.xxx port 655)
tinc.ubbink[9707]: xxx.xxx.xxx.xxx port 655: Network is unreachable
tinc.ubbink[9707]: Could not set up a meta connection to amys
tinc.ubbink[9707]: Trying to re-establish outgoing connection in 35 seconds
tinc.ubbink[9707]: Purging unreachable nodes

I couldn’t find why this was happening because when I used netcat to connect to port 655 via udp everything worked.

nc -vu xxx.xxx.xxx.xxx 655

Also a telnet to port 655 worked, but why wasn’t tinc able to make the connection?

How to make a file empty on linux

1 minute read Modified: 10 Aug, 2018

Why use :> instead of > ? During a IRC conversation somebody mentioned that using :> was a better way than using >. So to make a file named testfile empty you would use :> testfile The explaination is that :> is more portable. Some shells (such as zsh) auto-instantiate a cat in the current shell and listen for stdin when given a redirect with no command. Rather than cat /dev/null, : is much simpler.

iptables range is reversed and will never match

2 minute read Modified: 30 Jul, 2018

This blogpost was original posted on Capitar’s blog The problem When customers ask us to allow some IP addresses to their services they might give us an IP-range in the following way. 10.0.0.1-6 This means they want the following IP addresses to have access: 10.0.0.1, 10.0.0.2, 10.0.0.3, 10.0.0.4, 10.0.0.5 and 10.0.0.6. But when you use this notation with iptables it gives an warning. # iptables -A INPUT -m iprange --src-range 10.