An IP machine Q has a path to another IP machine H via three IP routers R1, R2, and R3.
H acts as an HTTP server, and Q connects to H via HTTP and downloads a file. Session layer encryption is used, with DES as the shared key encryption protocol. Consider the following four pieces of information:
$[I1]$ The URL of the file downloaded by Q
$[I2]$ The TCP port numbers at Q and H
$[I3]$ The IP addresses of Q and H
$[I4]$ The link layer addresses of Q and H
Which of $I1$, $I2$, $I3$, and $I4$ can an intruder learn through sniffing at R2 alone?
- Only $I1$ and $I2$
- Only $I1$
- Only $I2$ and $I3$
- Only $I3$ and $I4$