As some links on my blogroll start to turn into 404 errors it's time to do some cleanup and also to bring in some fresh blood :-)

Removed:

• mezzoblue
• Dave Shea
• Pepilog
• e.loge
• EDV
• sid.rstack.org/blog
• Code Candies
• thePacketGeek
• lovfoood

Added:

• charity.wtf

Happy 2019! I have learnt a new Vim trick:
When searching for some pattern with / (eg. /mystring), often the next step is to perform a replacement command. Now instead of re-typing the whole string, you can directly enter the substitution command with an emtpy search-pattern (:%s//newstring/), Vim then automatically re-uses the previous search pattern.

(via)

The Swiss Army Knife of Hashmaps — a very nice article from Ravi Shankar explaining how Google's SwissTable concept was implemented for Rust.

The Vagrant file provided by IBM for running QRadar Community Edition on Mac OS X currently does not work properly. It fails with the following error:

Failure: repodata/repomd.xml from centos-gluster38: [Errno 256] No more mirrors to try.
http://mirror.centos.org/centos/7/storage/x86_64/gluster-3.8/repodata/repomd.xml: [Errno 14] HTTP Error 404

The problem is that gluster3.8 was moved out of this CentOS repository and now the download fails. But the gluster3.8 RPMs are also provided with the QRadar CE installation ISO file.

Based on the workaround described here, I've extended the IBM provided Vagrantfile so that the RPMs are taken from the ISO file instead of the CentOS repository. With the modified Vagrantfile the automatic provisioning script no longer fails.

The instructions for running QRadar CE with Vagrant now look like this:

1. Download the zipfile with the original Vagrantfile and the accompanying helper files from the IBM website: https://developer.ibm.com/qradar/ce/
2. Create a folder and extract the zipfile:
   

   mkdir community_edition
   unzip QRadarCE_Vagrantfile.20171003084145.zip -d community_edition/

3. Download the modified Vagrantfile and overwrite the original one:
   

   curl -o community_edition/Vagrantfile https://blog.x-way.org/stuff/Vagrantfile

4. Make sure you have the requried Vagrant plugins installed:
   

   vagrant plugin install vagrant-disksize
   vagrant plugin install vagrant-reload

5. Make sure you have the QRadar CE ISO file (downloaded from the IBM website) in the same folder as the Vagrantfile:
   

   cp QRadarCE.iso community_edition/

6. Create the auto_install file to automatically install QRadar:
   

   touch community_edition/auto_install

7. Accept the EULA by adding the corresponding setup parameter in the Vagrantfile:
   Edit the Vagrantfile and add the --accept-eula argument to /media/cdrom/setup --no-screen to automatically accept the EULA
8. Change into the folder and start the QRadar installation (takes about 1 hour):
   

   cd community_edition
   vagrant up

Ernest Cline - Armada

Added another interesting blog to the Links: benjojo.co.uk

Ben builds and writes about a lot of funny small projects:

• Storing files in DNS caches
• Encoding data in dubstep music
• Building an IPv6-to-Tor gateway
• Switching SSH port based on a time-based token

Postfix provides the reject_unknown_sender_domain check which allows to only accept incoming e-mails sent from domains which actually exist.

Unfortunately there exists this one external service which uses a non-existing subdomain to send their notification e-mails. Thus all their notifications get rejected.

The following configuration allows to keep the reject_unknown_sender_domain check in place, but to exclude a specific domain from this check.

# snippet in main.cf
smtpd_sender_restrictions = check_sender_access pcre:/etc/postfix/sender_domain_verification

# exclude regex in sender_domain_verification
!/@domain\.to\.exclude\.com$/ reject_unknown_sender_domain

Your distribution might ship Postfix support for pcre matches in a dedicated package which needs to be installed separately (in the case of Debian you need to install the postfix-pcre package).

Added the following blogs to the Links:

• Thoughts on programming
• eklitzke.org
• rachelbythebay.com

Seems like the blog/RSS thing is getting traction again: It's Time for an RSS Revival (via)

With nflog_sniffer.cpp I've just added a C++ implementation to the nflog_sniff repository.

It uses the lean (and apparently also very fast) libtins library.

The nflog-bindings from Pierre Chifflier make it trivially easy to write a passive packet sniffer which can be controlled via iptables and listens to traffic on multiple interfaces at the same time.

As a little exercise I have written a simple DNS packet sniffer, once in Perl and once in Python:

To use the sniffer, first create an iptables rule like this: iptables -I INPUT -p udp --sport 53 -j NFLOG --nflog-group 123

Then start one of the sniffer scripts and observe the extracted DNS queries :-)

For a more convenient download I've also put the scripts in a proper Github repository: nflog_sniff