dmcrypt cheat sheet

Cheat sheet of some dm-crypt commands and configs that I seem to use somewhat frequently.

SSH Proxy: Server and Client Side of Using an SSH User Without Shell as Proxy Server

Imagine you want one of your machines to become a proxy - for external users to be able to access local resources or the internet as if they were on that machine. You could run a dedicated proxy server for that - but if the machine provides SSH and you want an easy solution, you can use SSH as well - without risking any shell-related issues.

Git security: enabe fsckobjects in ~/.gitconfig:

In order to prevent possible tampering with code in git repositories you work with (e.g. malicious manipulation of objects during clone, fetch, push...), check if these lines exist in your ~/.gitconfig and add them, if they don't.

Cracking RC4 messages that use weak RC4 reinitialization for each message part

This post deals with a short excerpt of a security and hacking related exercise at the University of Applied Sciences Upper Austria, Campus Hagenberg: we obtain the plaintext from an intercepted RC4 encoded message, from which we know that it uses an easy to crack re-initialization of the RC4 cipher for each message part.

Around the Firewall: ssh proxy and ssh port forwarding

If you happen to a) be behind a firewall which does not allow you to reach a certain destination on the web, or b) be outside in the web and cannot access a certain destination inside a network, the openssh implementation may help you: from the machine you're sitting at ("local machine") you just need …