NScan.org: the legend is still here ;)

This section is going to be constantly updated. Ask me more questions, and I'll add them here.

Q: Scanner locks up my connections. Is it normal?
A: If you have a Win95 or Win98 it's, er, "normal". You can avoid this by setting dynamic socket allocation. The thing is that Windows can't works at the load the scanner can. The number of socket descriptors is limited, and it results in the lockdown effect - when system can't open a new connection in another applications. Set the "dynamic socket allocation" switch in the option on. It will help. NT has no socket limits, but still be careful with a system resources.

Q: My connections seem to slow down or stop to respond, when I run NScan.
A: Sure, they will. You can't place a megabit load on the network while sitting on dial-up connection. You have to limit the speed, or you can also get an inadequate results - some open ports may be skipped. There is a limit you can set in an Options dialog.

Q: I tried to scan some ports on the server xxx.xxx.xxx.xxx. Port 80 was open, I could connect on it using Telnet or Iexplore. The scanner only reported port 25. I tried to scan only port 80, but it didn't detect it. What could be the cause?
A: That's really nice problem. The key of the problem is that that host can have a slow connection. If you'd used detailed output (absolute), you could notice that there are not only "connection refused" messages, but also "timeout" lines, that have only 2
meanings - one of the hosts is too slow (his or yours) or it's firewalled. Set detail level at least to "timeouts" and look (this is sometimes a really a powerful feature), maybe you'll find the balance. Just note that open ports will come up even if you have more than a half timeouts (don't lower the speed too much).

Q: I want to scan from to at the ports 1426,1436,1501,1644 because I'm looking for a Satellite communications. When I insert these IP's, the program not scan. Why? How I can do it?
A: I did not found such a bug in those versions that I've not already killed. But I really admire the problem...    don't scan such huge ranges, you will never scan all the Internet. It's accepted by scanner and it could work.... but for too long. Try to think yourself - your range applies to 17179869176 ports and even if you have a speedy connection, the resulting traffic and therefore time will be incredible (about 6-8 terabytes). Also please note that there is reserved, broadcast and multicast addresses, as well as loopback network (127.x.x.x). They will never be scanned correctly (only localhost, but I can't imagine, why would you need to scan localhost class A net).

Q: Scanner dramatically slows down when I scan the network. What is the problem?
A: You may have tried to scan reserved address block, invalid address class or you may get a firewalled network. In both cases scanner can't get the reply and waits until times out. Since Windows Sockets timeout constants are relatively high, as well as it automatically repeats the query several times, it's may take a long time to determine timeout. You can see it in the report while using "timeout" detail level. The examples are: D and more class networks (224.x.x.x and more) - invalid; - reserved block; UUNET networks (port 31337 is firewalled by UUNET's routers).