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 $I4$