please a help about UDP packet

[s.]

hello everybody,
i need ur help, i read in networking and some security on it, i have problem when i read that, it is:
i know that UDP is unrealiable , so i think that mean it has no 3-way hand shaking,
but when i read many papers, it said that UDP can be checked (by authantic method) in the first request packet, and if it not auth. the whole traffic is discard!!!!
please how is that??
doesn't the packets reach the destination out of order? so how can we recognize the first request packet from other packets?
and how to recognize the whole flow of that request?

thank u very much for any help and reply please i indeed need it
with regards
swa

[FordGT90Concept]

Originally Posted by s.

please how is that??

It's a series of handshakes. Client sends the server an encrypted password, server responds with an encypted key. Every future packet is encrypted/decrypted using that key. If any of this handshake is lost, they must perform a new handshake.

Originally Posted by s.

doesn't the packets reach the destination out of order?

It can. If you must receive packets in order, use TCP.

Originally Posted by s.

so how can we recognize the first request packet from other packets?and how to recognize the whole flow of that request?

You have to code that into your protcol design. UDP is only intended to transfer ~1KiB of data asynchronously. If whatever you are doing requires more than one packet, how to sort the mess is up to you. Usually, the first bytes of a packet specifies a packet type.

[s.]

thank u very much for ur reply, it is helpful
so please by that

UDP is only intended to transfer ~1KiB of data asynchronously.

do u mean that udp usually send 1 packet in it's transfer?

also please, the security that i read is between the client and it's nearest router, so here please, what is the series of the handshaking that happen here?

i don't want to send using TCP only, and the packets that transfered through is of all types, but i have problem in the UDP behavior in transfering

thank u in advance
with regards
sarah

[FordGT90Concept]

Originally Posted by s.

do u mean that udp usually send 1 packet in it's transfer?

The protocol only covers the transmission of a single packet but there's nothing to stop many packets from being sent/received. TCP can accept one packet as well but it is design to receive thousands of them in a specific order (requests those that are lost).

Originally Posted by s.

also please, the security that i read is between the client and it's nearest router, so here please, what is the series of the handshaking that happen here?

There's a DHCP handshake there where they share MAC address with each other and the router assigns an IP to the machine. As far as I know, it is not secure.

[s.]

by that

There's a DHCP handshake there where they share MAC address with each other and the router assigns an IP to the machine. As far as I know, it is not secure.

u exactly go when i want
thaaaank u very much
best regards