Can computers connected within a Network via Ethernet monitor access the information uploaded/downloaded on a different computer

Question

Suppose there are many computers connected within a Network.

Let's take 2 examples. Computer A and Computer B, connected within the same network.

Suppose, At the start of the day, say myself as an user using computer B.

I download and upload many things on the internet and my personal details through Ethernet network using computer B.

At the end of the day, can the computer A connected within the same network as computer B, can access the information that I have uploaded/downloaded to/from the internet through the Ethernet network connected as we all are in the same network?

If its not possible, who can monitor or have access to the information that I have uploaded/downloaded to/from internet within the same network?

Is it possible in WiFi network too?

Please help to clarify my doubt in simple terms with less technical jargon, as I am a Newbie.

Answer 1

Answer is No in if Both are COMPUTER A & B are LAPTOPS or Personal Devices. In case of Common Assets, there may be possibilities of retrieval of Websites accessed or username used for a specific website kind of stuff (if you have not followed safe browsing).

Also a Network Admin controlling the Firewall can monitor all your activities like websites/ Data transfer size and all.

But if you feel you have uploaded a file and someone connecting his/her LAPTOP/DESKTOP to that specific port can retrieve the file from Network- is not possible at all.

Hope, This is Helpful!!!!!!!

Answer 2

No, not normally.

1. Information about past connections isn't stored in a network. If you don't monitor it in real time, the information isn't accessible any more. Of course, information about anything can be logged on a device in a network - e.g. on a firewall or a syslog server.
2. A modern network is switched, so computer A only sees broadcasts sent from anyone or traffic addressed to A. Using obsolete repeater hubs or a wireless network, all traffic is visible to all nodes, which would enable logging of traffic on the frame level (data link layer).
3. Most actual Internet traffic today is encrypted above the transport layer. If you had access to the frame level you could see the IP packet level (network layer), and the transport-layer headers, but only unencrypted application data. You could see e.g. DNS requests and the connections (who's talking to whom) but the actual data that is transmitted would be encrypted and unintelligible.

The frame or packet levels are always visible on devices that forward those units, most prominently a (core) switch, a router, or a firewall.

For close monitoring, encryption is a serious problem, so many firewalls include features to break the encryption for analysis (SSL deep inspection using a man-in-the-middle technique) to be able to log/filter HTTPS URLs, scan the data for malware or bot traffic, implement data leak prevention (DLP), ...