IP packet format: Version Header Length Type of Service Total priority and the segment length indicator identifier number offset TTL protocol header source address and a destination address checksum option data
ICMP functions: It is a detective with the wrong feedback mechanism
ICMP package type
+ IP + ICMP header data header
ping format
ping -a: Displays the host name
ping -t: constantly ping
ping -l: changing the packet size in bytes and
ping -n: change the number of ping packets
ARP protocol
arp Address Resolution Protocol: resolve a known IP address to a MAC
arp mac address parsing process
PC1 to PC2 will send a message to check their cache table there is no mac address of PC2, if not we will send arp request (broadcasting), received checks to see if the host is your IP address, if it is your will mac address in a unicast manner to a PC1
ARP spoofing:
It is basically the same principle and ARP ARP spoofing attack, but the effect is not the same. The end result is ARP attack led to network outages, but the end result is to make the ARP spoofing traffic by itself achieve the purpose of monitoring or control.
Most network management software is achieved through ARP spoofing.
ARP attack
First clear ARP attack ARP reply is sent, but the MAC address of the ARP response to a false address, so when you want to communicate with other hosts, destination MAC address is set to lead to this false MAC address can not communicate properly.
For example: If you want to attack the host can not access the Internet, you need to send to the gateway or attack the host sends false ARP response. When the gateway receives the ARP response false update the ARP entry, and then if the gateway to the data occurs PC1, will be sent to a false MAC address of the communication fails.
Here can be illustrated, for example, Joe Smith John Doe called to give, he must first know John Doe's phone number, then he was told that John Doe's phone number is 12345678 (the number does not exist), then put Joe Smith 12345678 telephone call, so that you can not find a John Doe.