Artikel in Kategorie "Administration"

Interactive nftables Ruleset Editor

I wrote a simple shell tool to interactively edit the current nftables ruleset using a terminal-based text editor (respecting environment variable EDITOR and defaulting to vim). For testing purposes, it can optionally revert the changes after a timeout specified in seconds (option –timeout SECONDS, requires systemd-run).

GRE Setup for Bacula on a Mobile Client

The way Bacula works is: A backup client runs a TCP server process bacula-fd, waiting for a backup server process bacula-dir to connect and perform backup and restore jobs. There is a simple authentication mechanism, where bacula-dir presents a shared secret to bacula-fd to be granted access. Opening the bacula-fd TCP server on an exposed […]

Create or Append a debian/changelog Entry

Since i always have to look this up, everytime i need it, i write it down once, as „note to self“! NAME=“John Smith“ \ dch –create \ –package my-package \ –newversion 0.1 \ „Initial release“ And that’s it! 🙂

Generate Certificate Signing Requests (CSRs) for TLS Server Certificates

Overview In this article, a procedure is described to generate multiple certificate signing requests (CSR) for TLS servers, such as SMTP-, IMAP- or HTTP-servers, so that we can submit them to a Certificate Authority (CA). The CA will eventually perform the signature and return a public certificate to us. A Shell and the software OpenSSL […]

Methods of HTTP Caching

Preface I find the world wide web and the spectrum of methods and instruments that make it happen full of dubiousness and opportunity alike. Caching is generally known as one of the „hard problems“ of information science, and this is not different when it comes to technologies of the web. The text presented here, as […]

Comparing Distinguished LDAP Names

In a Bourne Shell script, a distinguished name (DN) for performing an LDAP-query is held in a variable: dn=“cn=Malmø,ou=County Capitals,dc=Sweden,dc=Europe“ For the purpose of demonstration, this example DN contains a non-ASCII character. Let’s write a Bourne Shell function that escapes such special characters as requested by RFC 4514 using perl’s Net::LDAP::Util: canonical_dn() { perl -s […]

So it is possible …

Update August 28th 2021: I have identified some TLDs that apparently can be used for testing purposes. I have updated the text as indicated. … to have DNS top level domains for bargains (.bargain), the bible (.bible), black friday (.blackfriday) and marketing and social networking (.buzz), but it is not possible to have a TLD […]

Determining User Access on a Linux Filesystem with „Classic Permissions“

Introduction Looking at a Linux filesystem, checking if a certain file or directory is accessible for reading, writing or executing by certain users or groups poses interesting challenges. Let the basic and seemingly simple question be: „Given a user X and a file Y, can it be determined if X has access to Y, and […]