Problem: When you get I/O errors on your computers hard disk, it’s usually urgent to copy all data to a new disk. If you try to do a 1:1 copy using dd, you will see that dd stops when it reaches the first bad sector. Solution: use the following command to copy from one hard disk to second […]
1:1 Copy of Hard Disks with Errors Read More »
Problem: A F5 load balancer LTM sends lots of data to some clients. Sometimes this fills up all the available bandwidth with 1 Gbit or more. At the same time the input traffic does not raise. The traffic charts look like if F5 is attacking some clients (reversed DDoS :-) ) Discussion: After some time of staring
Problem: “dd” is a useful tool on linux. E.g. you can copy a disk image or wipe a disk, etc. But dd doesn’t show you any progress indicator, and you don’t know how long you have to wait until it has finished. Solution: send signal USR1 to the dd process and it will show you how much data
“dd” shows its progress Read More »
For SSH, HTTPS, TLS SMTP,POPS, IMAPS you need a RSA key pair. Most Linux package installers produce this pairs automatically, but if you like, you can generate them yourself. The quickest method I found is: openssl req -x509 -nodes -newkey rsa:2048 -keyout servername.key -out servername.crt -days 1024 This command asks you some questions. The most
Howto generate an SSL key and self signed cert with openssl Read More »
Problem: A shell-script running every day short after midnight doesn’t work properly once per year after daylight-saving time adjustment. e.g. an expected logfile is missing (“somefile.YYYYMMDD.log”) Discussion: The Unix date command calculates the wrong date when used with “–date yesterday” on the day after daylight-saving time adjustment. # date Mon Mar 31 00:15:03 CEST 2014 # date
Unix/Linux date command fails when calculating “yesterday” Read More »
I don’t use desktop environments on Linux. I prefer small,fast, efficient window managers. Some years ago I used olvwm (open look window manager) which was dicontinued by sun. Then I switched to wmx which I patched for my needs, but still it was missing some features. Now I use openbox which is highly configureable yet
Openbox Config File Read More »
Problem: X11 has a classical copy/paste mechanism which is: select text – press middle mouse button in the target field. And there is a second copy/paste which was adopted from Mac and Windows which is: select text – Ctrl-C – click into tagert field – Ctrl-V. I prefer the classical approch, but in some web applications
Copy’n’Paste from Xterm to Chrome Read More »
Problem: PPTP from any client to an ASR1002-X Cisco does not work. PPTP Connections starts but in PPP LCP phase the connection fails. Solution: Cisco ASR1002-X with Software IOS-XE 15.3(2)S2 has no PPTP support. You have to take a different Router! Discussion: The weird thing is, that most of the PPTP stack is still configureable and working,
Cisco ASR 1002-X and PPTP Read More »
Problem: Ping from Linux computers to Windows Server 2012 with Direct Access fails for hours (no response) although connectivity is working (eg. HTTPS) Discussion: Ping from other windows machines and Cisco machines worked, but from Linux machines ping was not answered. I tried to find the difference between those ICMP Echo Request Packets, and reduced it to
Ping to Windows Server 2012 with Direct Access fails Read More »
Problem: for some applications a mouse coursor in disturbing. E.g. video players, signage display. Solution: the tool unclutter hides the mouse coursor after a chosen idle timeout. Unclutter is part of the main debian repository. Version: Debian 7.1
Hide Mouse Coursor on X11/Xorg Read More »