Scanner FAQ

Frequently Asked Questions

Additional support resources

To find additional questions and answers, and/or to ask your own questions, see the Scanner Support Forum.

Answers

The program does not open on Server 2003 x64, what should I do?

It may be necessary to run the legacy version of NetworkActiv Port Scanner 4.0 for it to load correctly on Windows Server 2003 x64.

What is a subnet scanner (also known as an IP scanner)?

A subnet Scanner is a utility used to find computers at a given IP subnet with a given port open.

For example: To find computers with port 139 open somewhere from IP 1.1.1.0 to 1.1.1.255 one may:

  1. Enter 1.1.1.0 as the IP.
  2. Enter 139 as the Port.
  3. Choose the last little check box below the IP box.
  4. Choose the correct Speed of scan (above fast only recommended for LAN scans).
  5. Choose Scan IPs from the Options button (located directly to the right of the IP box).

Note: There are 4 small check boxes below the subnet IP box, these are to choose the scanning range, the first is to scan entire 4 sections of the IP address, the second is to scan the last 3 sections, and so on...

Common uses of a subnet Scanner are:

  1. To find FTP servers, (port 21).
  2. To find HTTP servers, (port 80).
  3. To find Windows(c) file shares, (port 445).
  4. To find Telnet servers, (port 23).

What is a port scanner?

A Port Scanner is a utility used to find Open ports on an IP address (host), ports that are open on a system represent services, servers, and sometimes internet applications (possibly trojans), therefore a port scanner can inform you of such services, servers, etc. running on a local or remote system. Port scanning may assist you in the detection of trojans and other unwanted servers/applications, and is a great security tool.

For example: To find out if this computer is running a FTP server, one may follow these steps:

  1. Enter localhost as the Address.
  2. Choose TCP from the drop down scan type menu, (located to the right of the port scan Options button).
  3. Choose the correct Speed (MAX speed for scanning local system).
  4. Choose Start scan from the Options button, and if port 21 comes up then this computer is running a FTP server.

Common uses of a Port Scanner are:

  1. To check ones computer for trojans and servers.
  2. To check a remote system for trojans and servers.
  3. To test the security of a remote system.
  4. To test the security of a firewall on a remote system.

Why does the Port Scanner not find any ports?

Possible reasons:

  1. The IP address is invalid.
  2. The Timeout is set too low.
  3. The IP address being scanned has no ports listening.
  4. You are trying to access an external IP address, But are not connected to the internet/network that the remote IP address is on.
  5. The Speed is set too high.
  6. A firewall running on the local and/or remote system did not permit one or more of the packets out and/or in to and/or from one of the systems.
  7. The computer being scanned has a max packet(s) per second response, you are exceeding th
  8. Some form of network error or packet regulation occurred by one or more of the routers between the local and remote system.

Why does the subnet Scanner not find any IPs?

Possible reasons:

  1. The IP address range does not contain any valid IPs.
  2. The Timeout is set too low.
  3. The IPs being scanned are not listening on the port entered.
  4. You are trying to access an external IP range, But are not connected to the internet/network that the remote IP range is on.
  5. The Speed is set too high.
  6. A firewall running on the local and/or remote system did not permit one or more of the packets out and/or in to and/or from one of the systems.
  7. The computer being scanned has a max packet(s) per second response, you are exceeding this, and therefore did not return every packet.
  8. Some form of network error or packet regulation occurred by one or more of the routers between the local and remote system.

What is the difference between UDP and TCP?

UDP (User Datagram Protocol) is a protocol based on connectionless comunication. UDP is ideal for things like Video Streams and Multi-Player Gaming, where a few lost packets are not a big deal, and where speed is very importent.

TCP (Transmission Control Protocol) is a protocol based on a connection between two computers. It is used for normal internet applications such as web servers, FTP servers, etc.

What are the Timeouts for?

For TCP the timeout is to set how long the program waits for a reply on each port, if no reply within that time frame then the program declares that port to be closed.

For UDP the timeout is to set how long the program waits for a reply on each port, if no reply within that time frame then the program declares that port to be open.

Why does the UDP port scanner find ports that are NOT open?

Possible reasons:

  1. The UDP timeout is set too low.
  2. The RD(Relative Delay) is set too low.
  3. The Speed is set too high.
  4. The packet(s) did not make it there and/or back due to network error.
  5. There is a firewall running that did not permit all the packets out and/or in.
  6. The computer being scanned has a max packet(s) per second response, and therefore did not return all the packet(s).

What exactly does the Speed setting determine?

The Speed setting determines the maximum number of ports per second to attemp.

If the Speed is set too high for TCP then the scanner may use too much resources, and may miss some or all ports that are open.

If the speed is set too high for UDP then the scanner will find ports that are not really open.

Why when I save the lists can I NOT find the file?

Possible reasons:

  1. You saved the file with the wrong file extension.
  2. The disk you saved to did not have enough disk space, or is write protected.
  3. You did not save the file to a location you know.

Why are there two places to enter an IP and a port?

On the left side of the application, there is a start and stop port field, also, there is an IP/address field. These fields are for the port scanners and other host based operations such as ping.

On the right side of the application, there is an IP address field along with a port field. These are strictly for the subnet scanners and ping scanner.

How do I ensure top performance?

The keys to ensuring high performance are:

  1. Make sure there are no firewalls or packet sniffers running.
  2. Do not run high processor usage software at the same time.
  3. Windows(c) 2000 or higher is recommended.
  4. For TCP port scans, make sure the Max Threads (located in the Shared settings box) is not set too high, for Windows(c) 98/ME this setting should be around 75, for Windows(c) 2000/XP this setting should be around 500.

What are the Read timeouts for?

The Read timeouts are to set how long the program waits for data reply after connecting to a port.

What are the Multi-Packet ( MP ) settings for?

For port scanning this setting determines how many extra packets to send uppon finding a possible open UDP port.

For subnet scanning this setting determines how many extra packets to send uppon finding a valid computer (UDP w/port only).

The purpose of this setting is to lower the chance of finding UDP ports to be open when they really are closed.

What is Ping scanning?

Ping scanning is a scanning technique used to find IP's (hosts) that are currently up (connected) on a given IP subnet.

How do I paste an IP or domain name into the subnet IP box?

Paste the address/IP into the port scanning address box, then simply click the small arrow directly to the right of the port scan address box.

What is UDP ping mode for?

UDP ping mode vs standard (ICMP ping mode) mode: The difference is simply that UDP ping mode sends UDP packets to port zero on the host being scanned (port zero can never be listening, and will therefor reply), and standard ping mode sends standard ICMP echo request packets to the host being scanned.

What are the current known bugs/issues?

NetworkActiv Scanner 4.0 current known bugs/issues:

There are currently no known bugs or issues.

NetworkActiv Scanner V3.0 current known bugs/issues:

  1. If the port range specified for a port scan consists of more than 65536 ports it may cause the program to malfunction or crash.
  2. If a port scan is started by pressing enter while in a field of the port scanner side (left), and changes have been made to the port range, the changes will not be reflected unless the port scan Options button is pressed or the program is re-started.
  3. If ping is started and the ping dialog is closed by pressing the Esc button, the ping will continue until the program is closed.
  4. On the ping dialog, if the time-out is set too low and a ping is performed, a list item will be added to the list to indicate the lost ping and a list item will be added for the received ping, resulting in two items per timed-out ping.
  5. Many times when the program has just started the first ping will time-out.
  6. Trace-route does not work correctly on Windows(c) 98/ME.
  7. TTL setting on the Ping dialog does not work on Windows(c) 98/ME.

Note: These bugs have been fixed in the next release (Use button in About of program to occasionally check for newer versions).

In the case that you find a bug and/or issue in NetworkActiv Scanner that is not mentioned above please send us an email explaining the situation, your operating system, and the version of NetworkActiv Scanner you are using.

Why does the protocol scan find protocols that are invalid?

Possible reasons:

  1. The TCP time-out is set too low.
  2. Speed is set too high.

Why does the SYN scan stop after a moment of scanning?

When the SYN wait for reply check option is checked the scanner will not send more than the Max Stray packets without having received them back, if packets are lost during the scan this option will cause the SYN scan system to slow down and stop sending packets.

If this problem occurs it is recomended to uncheck the SYN wait for reply option and scan again.

What is Only scan known ports for?

When checked, the scanner will only scan ports that are in the port range specified and are in the internal port list (a list of common ports). Basically, if you were to enter from port 1 to 65535 for the range, the scanner would check all known ports. This type of scan will be faster because time is not wasted on the checking of un-common ports.