web browser traffic

[lazybum550]

Hey guys,

I was wondering what the tcp/ip traffic looks like when you request a web page from a web browser.
I know that it runs on http (port 80). However while looking at some ethereal data I found that the browser sends traffic out on some random port that get redirected to port 80. Is domain name resolution the reason for that?

 

[n0cmonkey]

That's the way systems work. Ephemeral ports (above 1023) are generally used to send requests to privileged ports (0-1023). The privileged ports generally require administrator/root level access to connect to, but ephemeral ports do not. So a regular user can bind to higher ports. If browsing the web required you to use port 80 locally, only administrators/root could browse the web.

 

[nweaver]

you would see a requrest from a high level port (your local port) go to the http server on port 80, and then see a reply (iirc, been a while) on port 80 from the server, to the high level port on your machine (several, actually, as it sends all the data required)