In computer networking a port is a software construct serving as a communications endpoint in a computer's host OS.

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Why is system32/ntoskrnl.exe blocking port 80? [closed]

Today I've tried to start the Visual Studio Developer IIS as usual on Port 80, but this time it has quit with an error that port 80 is already in use. With netstat I've found out, that an application ...
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Unexplained downloading

I was just watching as my bandwidth monitor spiked downloading a file. I checked my current netstat and I didn't recognize one of the IPs so I started capturing the data with Wireshark. The ...
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How does OS detection work in practice?

I was wondering how OS detection really works on Nmap. I know it is about to send different tcp probes to see how the target machine responds to them. But what kind of probes would distinguish a ...
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Which of these ports are safe to leave open, which are not?

I just ran nMap against my IP address and got the following result: PORT STATE SERVICE 21/tcp open ftp 22/tcp open ssh 23/tcp open telnet 80/tcp open http 443/tcp open https ...
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Router Ports open

What ports on my home router should be open, say if I'm only using it for browsing the internet. Right now these four are open, 23/tcp open telnet 53/tcp open domain 80/tcp open http ...
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Closed Port security

I have what I think is a security IT question (I'm more of a programmer myself). Assuming I am running a dedicated machine (say a PC) for a single program, meaning that the only port visible and open ...
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How do hackers take advantage of open ports as a vector for an attack?

It is widespread knowledge, and therefore a common practice, to close open ports on any machines connected to the internet. If for example, a typical program uses port xyz as it's communication ...
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Detected Port Scanning Attack in ESET Smart Security

I receive a number of notifications from ESET Smart Security about Port Scanning attack. But I'm behind a router. But as far as I know, computers behind a router is not accessible from others (Please ...
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Is opening both TCP/UDP less secured than just TCP or UDP when needed and why?

If application needs opened port X UDP, or X TCP combination. Is there any potential risk by opening both UDP/TCP as I usually am not sure which one the application uses?
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How to listen to all ports (UDP and TCP) or make them all appear open (linux)

I got an external Debian server. The problem is that my university campus doesn't allow connections to go outside when the port is different than TCP port 22, 80, 443, or UDP port 123. I tested them ...
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What configuration will allow another computer in the internet to probe my computer's ports?

I've just tested my computer with Gibson's port scan test: The test results stated that my system is "uncommon". It also said that my computer deliberately chose not to return. But I did not do any ...