why not a two way handshake

[rookie1010]

Hello,

you guys might have heard this question before, i basically want to know why we cant have a two way handshake, why is a three way handshake necessary.

why does a TCP/IP handshake need to be three-way. why can't it be two-way?

e.g. client A tells server B i want to communicate with you (Sync)
Server B tells Client A ok let's talk (sn/ack)

and then client A and server B can start talking, why then the need for the three way handshake?

 

[Ste]

CHAP? What security protocal are you talking about.
Its been some time since Ive read my network+ book..
So Im rusty.

Well, the only explaination I can offer is: there is a reason it is TCP. TCP Stands for, trusted connection protocal. So maybe they just wanted to be extremely trust worthy.

 

[King X13]

what if server b doesnt want to talk to client a? thus the asking if it is ok for these machines to connect. this way it has the option to reject client a before communications begin and something hardmful can be transmitted through.

 

[rookie1010]

thanks for the reply

in that case server b says that it does not want to talk to client a and there is no communication

 

[bla!!]

The reason for the 3rd packet being sent is so that server B knows that server A received it's ok for the connection.

So Server A sends the connection request to B, B sends back to A that it wants to establish the connection, then A will send back to B that it received the connection request. A lot of times this third part of the handshake is piggy-backed onto the first packet of the actual transmission.

 

[rookie1010]

thanks for the reply

but A was always ready for the request from the begining so why send an OK?

 

[hiren]

A is ready but B doesn't know that it has send the correct request to correct server. ))) to make sure for B that it is talking to A