Nunix

Recently, I had to forge UDP packets in order to resolve a challenge, but unfortunately, I faced a lack of documentation on RAW_SOCKET with the usage of UDP. So there is my feedback on how to forge correct UDP packets, with links to documentation I used.

To begin with, let me introduce what is a RAW_SOCKET, and what we can do with it. A RAW_SOCKET is a type of socket that allows you to bypass the operating system encapsulation. You are responsible to fill all headers of the different protocols used during the communication. Thus, you have to fill IP Header, and UDP header on our example. Furthermore, you have to comply with the different RFCs by computing yourself all checksums to keep packet's integrity while transmitting data in the wild.

A RAW_SOCKET requires root credentials, as forging a packet is really sensitive and allows one to do IP Spoofing on local network (ISP's protection are pretty efficient :)). You can also use them to do application spoofing in order to send application-specific data, or whatever you want.

Create the socket

Attachments:

client.c	[UDP Client with SOCK_DGRAM]	0 Kb
rawudp.c	[UDP Client, with SOCK_RAW and custom IP and UDP hdr]	5 Kb
server.c	[UDP Server, listenning on port 9930]	0 Kb

Lire la suite... Commentaire (1)

C'est dans un élan de paranoïa aigüe que je me suis penché sur la question du cryptage de fichier.

Après quelques rapides recherches j'ai appris que l'on ne dit pas " crypter " mais " chiffrer" ( http://fr.wikipedia.org/wiki/Chiffrement ) et surtout on trouve une multitude soft qui peuvent résoudre notre problème.

EasyCrypt et encfs marche très bien, mais j'ai une petit préférence pour OpenSSL.

Le cryptage/décryptage ce fait en ligne de commande avec une syntaxe très simple. De plus c'est rapide et multiplateforme.
Une multitude de solutions sont possibles, une des plus simples est la suivante:

chiffrer un fichier:

openssl  aes-256-ecb -in ficher_a_crypter -out fichier_crypte 

déchiffrer un fichier:

openssl  aes-256-ecb -d -in fichier_crypte -out fichier_decrypte 

Les plus curieux d'entre vous peuvent se pencher sur le TP de l'Université Paris Descartes pour découvrir plus de fonctionnalité de OpenSSL. www.mi.parisdescartes.fr/~osalem/enseignement/SSIC/TPopenssl1.pdf

Et voila, amusez vous bien,....

Jabref, a powerful tool to manage bibliography, has a special feature that let the user search bibtex entries online, and import them within your bibliography.

A problem occurs when you run JabRef behind a proxy (corporate or not), because no options is available to configure it.

Hopefully, JabRef is provided as a jar so we have the ability to modify proxy properties used by java.

Just run the following command :

 java -Dhttp.proxyHost="proxy" -Dhttp.proxyPort="8080" -jar "/where/is/the/jar/JabRef-2.6b2.jar"

 That's it, you can search for whatever you want on ACM portal, IEEE, etc. in few clicks. 

 For information,

• java properties for proxy (https, ftp, sock, etc.) : http://java.sun.com/javase/6/docs/technotes/guides/net/proxies.html
• Sorry for screenshot with vista skin, but as my corporate's laptop is using it, I need to work with it :D But this tip is cross platform.

Just a note to remember substitution :

:%s/\ {http\(.*\)},/\ {\\url{http\1}},/

Goal was, in a bibtex file, to make an anchor with each url, using \url{} command.

For example, 

 @MISC{ademe,
  title = {http://www.ademe.fr},
  note = {L'Agence de l'environnement et de la ma\^itrise de l'\'energie},
}

became

 @MISC{ademe,
  title = {\url{http://www.ademe.fr}},
  note = {L'Agence de l'environnement et de la ma\^itrise de l'\'energie},
}