Introduction to TLS v1.2

computer web network tls cryptography

Some notes about how TLS v1.2 (Transport Layer Security) works. The goal explain what is going on in a network traffic dump, the role of the different TLS extensions, the impact of the different cipher suites on security, etc. It includes several diagrams and many references.

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Introduction to the Diffie-Hellman key exchange

computer network cryptography tls diffie-hellman

The Diffie-Hellman (DH) key exchange (and variants thereof) is widely used in many protocols (such as TLS, SSH, IKE (IPSec), Signal, etc.) to bootstrap some symmetric key material which may then be used to secure communication channel between two parties. This introduction focuses on the different ways the DH key exchange is used in practice in several protocols (especially TLS) and the impact of these different approaches on the security. This is intended as a prelude for the upcoming next episodes about how TLS works.

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GNU/Linux host name resolution

computer network dns system

This post describes different software components involved in host name resolutions and DNS configuration on GNU/Linux systems. It consists of a diagram and some accompanying explanations. The goal is to give some pointers and references to understand how to troubleshoot host name/DNS resolution problems and configuration problems on GNU/Linux systems.

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Using dig as a LLMNR or mDNS CLI Lookup utility

computer network dns lmnr mdns

I was looking for a LLMNR commandline lookup utility. Actually, dig can do the job quite fine.

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Foo over SSH

Using SSH as a transport for your protocol

computer network ssh unix

A comparison of the different solutions for using SSH2 as a secured transport for protocols/services/applications.

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OpenSSH ProxyUseFdPass

computer network system ssh python

While looking at the OpenSSH ssh_config manpage, I found the ProxyUseFdpass configuration I did not know about. It is apparently not widely known or used.

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