The Port Scan window allows you to scan a range of protocol ports to check for available services (listeners). This is especially useful for testing network security including firewalls by verifying that there are no unintended services available.
Enter the IP Address of the host you wish to scan along with the starting and ending port numbers in the corresponding fields and press Scan to begin scanning. If you have access to a Domain Name Server (DNS), you can type a DNS host name like "www.apple.com" (or IP address) in the name field and press Return. To lookup a name or address, type the name or address in the corresponding field and press Lookup (the small magnifying glass next to the name field). If you leave the Ending Port empty, only the Starting Port number will be scanned. You can also specify a port range in the address or name field using the form address:start-end.
A popup history menu keeps a list of Recent Targets. The content of the Name field is added to the history menu when a test to that name is invoked. The Name or Address field is added to the history menu when the Lookup button is pressed. If the menu becomes full (10 entries), the least recently used item will be replaced. To remove an item from the history menu, select that item while pressing the Option key. Notice you can type an IP address in the Name field to have it added to the history menu.
You can scan for TCP services, UDP services, or both.
The hop limit specifies the maximum range in hops (number of routers) the scan will pass through. Notice that port scanning can be used both to check the security of your own network, and to probe for weaknesses in remote networks. Some hosts or routers may interpret port scanning as a hostile attack and cut-off subsequent service. The Hop Limit helps prevent accidental scans beyond your local network. As the Hop Limit increases above 5, the scanning rate decreases to make port scanning remote sites less hostile. Setting the HopLimit to "0" or emtpy disables the limit.
TCP ports are scanned by trying to open a connection to each port and waiting 1 second to see if the connection is accepted or cancelled (Reset) by the remote peer. UDP ports are scanned by sending a UDP datagram to each port and checking for an ICMP destination unreachable response. Since detecting a UDP listener depends on not seeing an ICMP response from the target host, spurious ports may appear if the path to the remote host is unreliable. You can use the status headings in the lower left corner of the window to verify how many responses have been received.
Additional Features:
When you invoke one window from another, the corresponding data is automatically transferred.
If you have Internet Config installed, you can make IPNetMonitor a helper application for URLs of the form <portscan://192.168.0.1:1-100/tcp/udp/hoplimit=5>.
You can select the results of a Port Scan and copy them to the clipboard as plain text (for pasting into email messages). If you include the first row of the table in your selection, the table headings will also be copied as shown here.
<portscan://192.168.0.1:1-100/UDP/hopLimit=4>
Port Type Description
The first line is the URL for this scan. If you use Internet Config and have selected IPNetMonitor as the corresponding helper application, you can rerun the scan by command clicking on the first line.
Keyboard Shortcuts:
Cmd-Period Abort scan in progress
Cmd-T Ping scan destination
Cmd-R Trace Route to scan destination
Cmd-K Test Link Rate to destination
Cmd-B Transfer scan destination to Subnet Calculator
