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How can I find out the IP address of a device?

Most of the IP devices come with a factory default IP address. If available, check it out from the User Manual, which also should report the username and password to log in to the device.
Some devices have the DHCP (Dynamic Host Configuration Protocol) enabled: as soon as you connect them on the network, they try to discover a DHCP Server, and ask it to assign them with a dynamic address. If no DHCP server is available on the network, they can fall back to the factory default IP address, or they can use a ZeroConf/APIPA (Automatic Private IP Address) address belonging to the 169.254.0.0/16 subnet.
The quickest and more reliable way to find out which address the device is configured with is to use a network traffic analyzer.
Wireshark (www.wireshark.org) is a free and really powerful tool to see what is running inside your network, which can be used to discover IP addresses as well. The procedure is simple:
- download and install Wireshark, including all the required drivers (WinPCap);
- connect your PC to the same LAN where the device whose IP needs to be discovered is connected to;
- run Wireshark; if you know the MAC address of the device (usually reported on a label sticked on the unit), you can configure the following capture filter to avoid useless traffic: ether host <MAC address>;
- restart the device;
- let Wireshark to capture the traffic; as soon as the device finishes its boot procedure you should see incoming packets, with the IP address you are looking for reported on the Source Address field.
Note that 0.0.0.0 is not a valid address. It just means that the device has the DHCP enabled and it is trying to reach a DHCP server to gather a proper address. Wait for a while until the autoconfiguration procedure is finished.

Daniele Bottini

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Last revision for the ONVIF interface requires the compliant units to use the DHCP by default.
If the unit is not assigned with an address by any DHCP server, it will not take any default address, but a ZeroConf/APIPA address inside the 169.254.x.x class.
Such addresses are not fixed, they are chosen by the unit with a pseudo-random algorithm.
But there's a good new: due to the algorithm itself that uses the MAC address as "seed", the unit should select the same Zeroconf address each time it starts. It means that the discovery should be done just once.
It's worth to learn how to use Wireshark really soon...

Daniele Bottini 0 votes
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