cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
310
Views
7
Helpful
4
Replies

General TCP protocol communication question

msrohman
Level 1
Level 1

If a (PC) client sends a TCP SYN packet to a system using a destination TCP port 80..and that system is not listening on TCP port 80..does the system respond with some sort of TCP packet?

Thanks,

Mike

4 Replies 4

a.kiprawih
Level 7
Level 7

Hi,

If tcp 80 is not opened, the system will not give any respond or acknowledge the syn request.

Rgds,

AK

Hmmm....what about ICMP port unreachable??? :)

mhellman
Level 7
Level 7

You should try it yourself using tcpdump or ethereal or whatever to capture the traffic. Different operating systems may behave differently. I believe the typical behaviour is to return a TCP rst...so the answer is yes.

Looks like Windows responds with RST-ACK.

Hope that helps!

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: