NSE4 · Question #441
Which of the following statements is true regarding the TCP SYN packets that go from a client, through an implicit web proxy (transparent proxy), to a web server listening at TCP port 80? (Choose…
The correct answer is A. The source IP address matches the client IP address. D. The destination IP address matches the server IP addresses. E. The destination TCP port number is 80. In a transparent web proxy setup, the client's SYN packet retains its original source IP, and the destination IP and TCP port remain those of the intended web server.
Question
Which of the following statements is true regarding the TCP SYN packets that go from a client, through an implicit web proxy (transparent proxy), to a web server listening at TCP port 80? (Choose three.)
Options
- AThe source IP address matches the client IP address.
- BThe source IP address matches the proxy IP address.
- CThe destination IP address matches the proxy IP address.
- DThe destination IP address matches the server IP addresses.
- EThe destination TCP port number is 80.
How the community answered
(27 responses)- A74% (20)
- B19% (5)
- C7% (2)
Why each option
In a transparent web proxy setup, the client's SYN packet retains its original source IP, and the destination IP and TCP port remain those of the intended web server.
In a transparent proxy, the proxy intercepts traffic without the client being explicitly aware or configured, meaning the source IP address in the packet header remains the original client's IP.
If the source IP address matched the proxy's IP, it would indicate an explicit (non-transparent) proxy setup, where the proxy originates the connection to the web server on behalf of the client.
In a transparent proxy setup, the proxy intercepts traffic based on network routing rules, not because it is the explicit destination IP address in the client's SYN packet.
The client's intention is to communicate with the web server, so the destination IP address in the SYN packet will be that of the intended web server.
Standard HTTP web servers listen on TCP port 80, so the destination TCP port in the SYN packet will be 80.
Concept tested: Transparent web proxy operation (TCP SYN)
Source: https://docs.fortinet.com/document/fortigate/7.4.0/administration-guide/575308/explicit-web-proxy
Topics
Community Discussion
No community discussion yet for this question.