IP Addressing Structure:
IPv4 Address = 32 bit # written as dotted decimals
Always paired with a 32 bit mask
Computers evaluate &
E.G. 10101000 <- high-order that side, -> low order this side.
Network = group of hosts with identical network addresses.
Some portion of the low-order bits = host address.
From our 32 bits, the # of bits used in the host portion determines how many hosts we can have in our network.
E.G. if 200 hosts in our network. We need enough bits in the host portion to make 200+ numbers
2^7 = 128, 2^8 = 256, therefore 8 bits minimum are required to get 200+ hosts.
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Tags: vlan, cisco, switch, ip, router, wan
Communicating over the Network.
Local Area Network (LAN)
A LAN is a network confined to a relatively small space. (still like an island but a little bigger);
Lan’s are a single enterprise that is locally administered.
Problem faced with a LAN – How to share information in different geographic areas.
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Tags: wan, cisco, 802.1q, ip, switch, router
Bitmindframes cisco study guides.
This will show you the basics of the cisco IOS command line interface and the different modes.
After several lines of information on the screen you should eventually see:
Would you like to enter the initial configuration dialog? [yes/no]: n
On some routers and switchesyou may see the following message.
Would you like to terminate autoinstall? [yes/no]: y Router> or Switch>
Privilege Mode
Router> enable
If you are prompted for a password type: class or if that does not work, type cisco
Use the “?” to view the list of available commands or command options
Router> ?
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Bitmindframes cisco networking study guides
EIGRP Commands
Enabling EIGRP Routing
Router(config)# router eigrp AS number (Must be the same on all routers)
Router(config-router)# network network-address [wildcard mask]
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Security on a switch
eMac address flooding or overflow attacks
Switches learn a source MAC address from the MAC address table
If a frame enters a switch and it does not find the destination MAC address in the table, the switch acts like a hub and floods it out all ports. Mac address tables have a limited size.
MAC address flooding uses this limitation to bombard the switch with fake addresses until the table is full. The switch then enters fail-open mode and will act like a hub.
As a result, an attacker can see all of the frames passing through the switch.
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