Analysis Of IPsec

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entered into the protocol registry under the numbers 50 and 51. If you or your ISP already implemented basic rules of packet filtration on your gateway routers, then you need to add these two protocols to the list of allowed protocols. Because of the field “protocol type” of the header of IP-packet will now be identical with IPSec envelope, now the original type of transport protocol fits into the “protocol type” field inside of IPSec header.
IPSec protocol can be used in transport as well as tunnel mode. In the first case IPSec header is placed between network (IP) and transport (TCP or UDP) headers of the “normal” IP-packet. Transport mode is made for use on the end systems. Functioning in this mode will reflect in all applications in the systems and in most cases there will be a need for a reprogramming of the existing applications.
Tunnel mode IPSec requires regular IP-packets to be put inside of the IPSec envelope, and that envelope is placed inside of other...