Par défaut, ssh ne sait pas se connecter à un serveur si le client est placé derrière un proxy. Pour ajouter cette fonctionnalité, il faut :
– installer le paquet connect-proxy
apt-get install connect-proxy
– ajouter un fichier ~/.ssh/config (juste pour un compte) ou /etc/ssh/ssh_config (configuration globale) contenant les lignes suivantes :
# on n'a pas besoin de connect pour le réseau local
# il faut modifier ou ajouter des lignes Host pour décrire votre réseau local Host 192.168.0.* ProxyCommand /usr/bin/connect %h %p # toutes les autres adresses utilisent la commande connect
# il faut remplacer l'adresse IP et le port par les valeurs de votre proxy
Host *
ProxyCommand /usr/bin/connect -H 192.168.0.1:8080 %h %p
On peut alors se connecter sans problème à un hôte par la commande classique : ssh identifiant@serveur
Today I found myself reconfiguring a wireless access point I hadn’t used in a very long time. I no longer have the manual (so I could reset it to factory defaults) nor do I remember what the obscure IP address I configured it with was. Luckily I do know what network it’s setup for ( 192.168.1.x ) but I don’t want to have to try to connect to all 254 IP addresses (192.168.1.1 through 192.168.1.254) as that would take quite some time.
So what I’m going to do is use Nmap a swiss army knife for network operators and system admins. What we’re going to do is use Nmap to scan the entire network and tell us which IP addresses are active. This will allow us to drastically reduce the number of IP addresses we have to try.
There are Nmap versions for all three major OS’s *nix, OS X and Windows. I’ll be showing you the syntax for the *nix/OS X version.
nmap -sP 192.168.1.0/24
replace 192.168.1.0/24 with whatever network it is you’re trying to scan.
The /24 is the netmask of the network in CDIR notation. If you need a cheat sheet you can find one here
Once you press return (or enter) Nmap will start to work pinging each and every IP address on your network and noting which ones respond and which don’t. (Note that if your device has a firewall that discards ping requests it will appear to be down to this scan)
You’ll quickly get an output similar to the following
Starting Nmap 4.50 ( http://insecure.org ) at 2008-08-19 10:15 PDT
HOST 192.168.1.25 appears to be up.
MAC Address: 0:0F:1F:4C:0B:E6 (WW Pcba Test)
Nmap finished: 256 IP addresses (3 hosts up) scanned in 5.711 seconds
Source: NixCraft
Q. How do I detect port scan attacks by analyzing Debian Linux firewall log files and block port scans in real time? How do I detect suspicious network traffic under Linux?
A. A port scanner (such as nmap) is a piece of software designed to search a network host for open ports. Cracker can use nmap to scan your network before starting attack. You can always see scan patterns by visiting /var/log/messages. But, I recommend the automated tool called psad – the port scan attack detector under Linux which is a collection of lightweight system daemons that run on Linux machines and analyze iptables log messages to detect port scans and other suspicious traffic.
psad makes use of Netfilter log messages to detect, alert, and (optionally) block port scans and other suspect traffic. For tcp scans psad analyzes tcp flags to determine the scan type (syn, fin, xmas, etc.) and corresponding command line options that could be supplied to nmap to generate such a scan. In addition, psad makes use of many tcp, udp, and icmp signatures contained within the Snort intrusion detection system.
Install psad under Debian / Ubuntu Linux
Type the following command to install psad, enter:
$ sudo apt-get update
$ sudo apt-get install psad
Lire la suite…
Quand votre nom de domaine pointe vers un hébergement mutualisé, vous n’avez, la plupart du temps, pas le droit de modifier les VirtualHost du serveur Apache.
Virtual Hosts
Pour pallier ce manque, une redirection s’impose mais par un autre biais: l’utilisation de l’URL Rewrting. Lire la suite…
Un jour vous pouvez resté bloqué par un mot de passe perdu pour accéder à Webmin et vous auriez besoin d’un moyen de le changer.
Voici comment: pour commencer, connectez-vous à votre système en ssh.Vous devez trouver où Webmin est installé et donc le chemin que le script utilisera pour réinitialiser le mot de passe. Lire la suite…
