Archive for November, 2008

Layer 2 traffic filtering can be very useful when you want to drop packets closer to the source because you can do this on L2 next-hop which is the switch where the devices are connected. Based on mac-address, Layer 2 filtering can be apply using one of the two most common method: Port Security and MAC...

The official term of Cisco for Packet sniffing is  SPAN ( Switched Port Analyzer ) also called sometimes port mirroring or port monitoring and it’s purpose is to select traffic from a source and send to a destination with a network analyzer tool. You can find out there terms like RSPAN, PSPAN,...

One of the most used method for remote access today is SSH protocol. Even most on the network engineer say what is so complicated in the process of the enable , disable , reconfigure of the SSH process, my experience proved me that it can be really complicated, if you mess up stuff there. One of the...

Spoofing is a kind of network attack to compromise your network security with the intention of traffic capture which will enable an attacker to get access to confidential data. Usually a spoof attach is associated with IP spoofing, which means that the source IP of the packet which arrive to your device...

I had lately to configure compressed real-time protocols (CRTP) over a Frame-relay link. I thought that it will be good to make a tutorial about how to configure this on the Serial interfaces (with HDLC or PPP encapsulation) and on the Frame-relay interface. Another type of interface supporting this...

Some time ago a person asked me to set the HTTP traffic to 256 kbits during weekdays from 8:00 – 16:00, to limit “the fun” in the office while other are working. In theory I’m against this type of policy, because if you have a team of network engineers and they have to access...

In this tutorial I propose to show something that is not very used these days, or at least not every day, but which can be tricky if you don’t know how to approach this type of configuration. To understand this, I assume that you know the basics about PPP, FR and Multilink. I will make a short...

In a well controlled environment, false information routing should not reach your OSPF domain, as network engineer take care what to advertise and what not into OSPF. But there are cases when you have to deal with 3rd party companies somehow, and you want to be sure that nothing in injected by mistake...