Missing IP addresses and host names in trial version
2 posts · Closed
David Guest
When I scanned with the trial version of Port Mapper, it didn't list IPs or host names for most of the 10 entries that the trial displays. MAC address, VLAN and Speed are listed fine. Is there a setting I didn't set correctly?
Ann SoftPerfect
Normally switches don't report any IP-level information. The Port Mapper only gets a list of switch ports from the switch, along with information about MAC addresses connected to each port. There is no IP address information in the list, and there is no direct way to convert a MAC address to an IP address.
To resolve MACs to IPs and then to host names, the Port Mapper does one of the following:
- If network scanning is enabled in the settings on the Discovery tab, it will scan the entire local subnet and create a lookup table of IP addresses associated with each MAC address. This can only be done in the local subnet, because the ARP protocol used for IP-to-MAC resolution is not forwarded by routers between subnets.
- If your router supports SNMP, its details can be entered in the Port Mapper, which will then query the router about known IP-to-MAC mappings.
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