Urgent Flag of TCP, Computer Networks

The Urgent Flag(URG) is set whenever the sender’s Application Layer wants to send some urgent data to the receiver. In this case, the Transport Layer does not wait for enough data to achieve maximum segment size. Now, my question is how do the routers in between recognize that the packet needs to be forwarded urgently(they do not have the transport layer)?

How did YouTube know I watched a locally stored file on my computer?

I ripped a few videos from YouTube (using y2mate) about a week ago of guitar lessons from a player named John Redbourne in case they disappear. I saved them on my local hard drive in a folder called “Redbourne Guitar” and the files are named after after the songs, like “Salisbury.mp4” etc.

Anyway, I just watched one of the videos off my hard drive, and lo and behold, when I logged into YouTube, my recommended feed was full of John Redbourne videos. I haven’t searched or done anything online related to John Redbourne since I downloaded the videos. How did YouTube know I watched it?

Using Windows 10, Firefox, and played video with default “Movies and TV” app that comes with Win 10.

Is XSS a solved computer science problem?

I have a fundamental theory question. Is looking for cross-site scripting a solved computer science problem? Or is it an open problem? Does it approximate the halting problem, injection problem or similar known CS problems?

Or is XSS not intractable but just tedious to find and fix as there are many possible sources and sinks to a scripted web page, poor programmer understanding of the vulnerability, etc or the plethora of web technologies out there that impede the solution to a sound solution? (I’m thinking about content security policy as an equivalent of NX bit in native code).

Anyone can point me to any resource (academia included) would be much appreciated.

When I try to SSH into my computer through its public IP the server’s host key fingerprint is different?

When I SSH into it through my local network, and when I actually go and check with ssh-keygen I get 1 rsa fingerprint. And when I try to SSH in though my public IP I get a different host fingerprint shown in putty. This host fingerprint does not appear to be the fingerprint of any of the host keys (or even client keys, I checked) on my server. It is totally unknown to me.

Am I the victim of an attempted man-in-the-middle attack? And if so, is there anything I can do so that I can actually SSH into my server remotely without compromising my server’s security?

Contents in computer science?

What are the contents in computer science, for I am picking it for my GCSE’s and have an interesting in programming and coding. It has been iffy trying to teach myself but I am currently learning python and wod like to move onto learn different languages used in cybersecurity and so on. Is there anything more to it that I should practice and revise on?

Not able to change computer date

I am using Ubuntu on my computer and the date is Feb 2018. If I try to change the date using date command, my PC reboots and after reboot, date is same.. I reinstalled the os but it’s the same issue. It seems a hardware issue. Does anyone know what exactly issue is or how to debug further.?