Category Archives: linux

Linux: query remote ntp (and show time difference)

Sometimes you just want to query a remote ntp server (and maybe see the difference between the two clocks). In this case you can use the tool sntp. From the sntp man page: The default is to write the estimated …

Read more »

Howto: Disable persistent Network Interface Names (Debian Stretch)

How to disable persistent network interface names in Debian 9 (Stretch) edit /etc/default/grub and change the following line GRUB_CMDLINE_LINUX=”net.ifnames=0 biosdevname=0″ afterwards run “update-grub“

Quickly create a (swap)file on linux

The traditional way for creating a linux swapfile would be using dd to create an empty file e.g. A faster way is to use “fallocate” e.g. 1) http://www.cyberciti.biz/faq/ubuntu-linux-create-add-swap-file/ Don’t forget the usually procedure for swapfiles: References   [ + ] 1. ↑ …

Read more »

Moving to KVM

Since our beloved OpenVZ virutalisation technology is not moving in a direction we are comfortable with, we are currently evaluation several virtualisation technologies. One the the possible options is KVM. This is not a full tutorial about KVM, there are …

Read more »

Running “backticks” commands on remote servers

Sometimes it’s necessary to run a complex command on a remote server witch also includes some “backticks”. Usually these commands are interpreted by the local shell so you need to use a little trick to force execution on the remote …

Read more »

Update for the Checklist on “mailout” servers

This is an update to the checklist to create a prefect mailout server: Original Checklist Setup DMARC DNS Record to receive mail delivery reports https://www.unlocktheinbox.com/dmarcwizard/ btw: I Just started adding all those settings to my own domain too. Google DKIM …

Read more »

Cloudflare and Haproxy Lodbalancer

We are currently trying out the cloudflare service to protect one of our company service. In front of this service we are using haproxy as SSL endpoint and loadbalancer. Cloudflare adds a number of custom headers1)http://www.linuxorz.com/2014/10/cloudflare-haproxy-get-real-ip/: In order to extract …

Read more »

Java SSL Certificate Verification Error

If you come across the situation, that your java programs are not able to connect to ssl encrypted services, it might be most likely that the java cacerts keystore is empty or not uptodate. This might also be due to …

Read more »

Hardening SSL

Update: 2014/01/17: Again a few weeks have past without finishing the article. So I’m going to publish it anyway even it it is unfinished work yet. I also disabled OCSP Stapling again. I’m using StartSSL and I’ve had some issues …

Read more »