May 15, 2010

Linux Kernel Route Cache

To understand the importance of the routing cache, it is important to keep in mind and visualize the 3 main routing hash tables in use in the kernel for routing decisions… the Route Cache (what we will be discussing), the Route Policy Database and the Route Table. It is also in this order that the network subsystem queries the tables to make a forwarding decision. To display the “Route Cache”, one could simply issue the “ip route show cache” command. ... Read more

October 30, 2008

How to reverse engineer a subnet

Alright.. Alright! everbody have their own method to reverse engineer a subnet… Here is a technic and way that works for me and might work for you. Let’s take a random private ip. IP: 192.168.1.95⁄27 And let’s try to figure out its network range. In such case, we will take the lowest subnet octect, which here is 224 (remember that a subnet bit of 27 is 255.255.255.224)… let’s therefore convert it into binary. ... Read more