Scanning for IP address lets you have better control over your network. With 1-2 commands, you can quickly map out the devices in your network and the IP addresses that they are using. But to understand how to scan a network, first, you need to understand how are IP addresses assigned.
Follow these four simple steps to scan your network for IP addresses in use:
- Open a Command Prompt window.
- On Windows or macOS type ipconfig or on Linux type ifconfig. Press return. Note down the subnet mask, the default gateway, and your own computer’s IPv4 address.
- Enter the command arp -a to get a list of all other IP addresses active on your network.
- Enter the command ping <IP_address> giving any of the addresses returned by ARP in order to test the response times to that node – don’t include the angle brackets that are shown in that example.
DHCP (Assigning IPs Dynamically)
An automated process in networking, called DHCP (Dynamic Host Configuration Protocol), assigns IP dynamic addresses to hosts as soon as they enter the network. In a home or small network, the DHCP server is usually a part of the router. When you come into the network, the router will look for an available IP address in its pool and assign it to you, so that your device can communicate with others without any conflict.
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Dynamic allocation of IP addresses is a great advantage for both end-users and network admins. But sometimes you would need to have some control in order to manage and troubleshoot your network more efficiently.
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If you are here for free tools and trials, here is our list of the four best tools for discovering IP addresses on a network:
- SolarWinds Engineer’s Toolset Ping Sweep – EDITOR’S CHOICE This utility scans a network and records every IP address that is in use. The Engineer’s Toolset also includes subnetting tools for DHCP management and the Open Port Scanner. Runs on Windows Server. Get a 14-day free trial.
- ManageEngine OpUtils – FREE TRIAL A suite of network address monitoring tools that covers IP addresses, MAC addresses, and port numbers with a cut-down free version also available. Installs on Windows Server and Linux.
- Angry IP Scanner A free network scanner that identifies all connected devices and lists their IP addresses plus connection response speeds. Available for Windows, macOS, Linux.
- MyLAN Viewer A network scanner that identifies all connected devices and lists their IP addresses and MAC addresses. Runs on Windows.
What will you learn in this Tutorial
In this tutorial, you will learn the basic networking skills on how to scan a network for IP addresses. We will scan a network with native OS commands, find which addresses were assigned dynamically, which statically, and test their connectivity.
In the end, we will compare some free IPAM tools aka IP address scanning tools that can give you additional information. To improve your IP addressing insights, even more, we will show you some tools that allow you to track IP addresses and even manage them.
Simple IP Scanning
Operating Systems, like Windows and Linux, come with their own native simple networking set of tools. Commands such as “ipconfig”, “arp -a”, or “ping” allow simple scanning and troubleshooting.
The simplest way to get a quick list of IP addresses and their devices connected to your network is with those OS native commands found in the command line. With a list of the assigned IP address and their devices, you can easily find the devices that are causing the most problems.
- ipconfig This command displays all network settings assigned to one or all adapters in the computer. You can find information such as your own IP, subnet, and Gateway. For Linux and MacOS is “ifconfig”.
- arp -a When you issue the “arp -a”, you’ll get IP-address-to-mac conversion and the allocation type (whether dynamic or static) of all devices in your network.
- PingIt helps determine connectivity between two hosts and find the IP address of a hostname.
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Reading The Output
Finding your own network adapter configuration
In the following screenshot, you’ll see the output from the ipconfig command. On a Windows, the ipconfig command can be entered through the Command line.
Go to Run > type cmd > type ipconfig
- This Windows computer has 5 network adapters, but the last one (Wireless LAN adapter Wi-Fi) is the only one connected to a network. The rest are disconnected.
- In this network, the router (or Default Gateway) is playing the role of the DHCP server. It is assigning the IP address dynamically and giving access to the Internet.
- You are reading two of the most important IP addresses for your device; Your own device’s IP (IPv4 and IPv6) and your Gateway. The Subnet Mask is also very important, it shows that you are on the same subnet as the gateway.
Now you know your subnet, which in this case is 192.168.1.0/24 (using the CIDR range). Now you need to find the rest of the IP address in your network.
Scanning your Network
The job of the ARP protocol is to map IPs to MAC addresses. It provides a method for hosts on a LAN to communicate without knowing any address and create a cache of information. When a new computer enters the LAN, it receives an IP and updates its ARP cache with the Gateway information. This ARP cache can be found using the “arp-a” command.
- Use the command line to enter the “arp -a” command.
- This computer has been connected for some time into the LAN, so its ARP cache is very precise and complete. The first IP address shown in the display is the Gateway (the same we found through the ipconfig command).
- The output shows the IP, the MAC addresses, and their assignation type. The addresses displayed here were dynamically assigned by the DHCP server in the LAN. All of these IPs are devices connected to the LAN (192.168.1.0/24). The other static addresses are reserved for Multicasting.
- With the MAC information, you can know the vendor. Try searching for vendor prefixes or use an automatic online tool such as MACvendors.
Testing Connectivity
Finally, with some information, you can test connectivity. In the following test, we tried an extended ping with “ping -t” to the gateway. With this, you can learn some simple insights about delay and latency.
From the list generated by the ARP command, you could ping all the live hosts. Or you can go beyond and ping the entire subnet to find hosts not found by the ARP (but that would be too much manual work…). Later, we’ll discuss how to automatically ping entire subnets at once.
Enhancing IP Scanning
Although having a list of devices and their allocated IP address will give you good insights, the information will not be enough when your network scales. Manual IP scanning in multiple subnets and BYOD (Bring-Your-Own-Device) scenarios is nearly impossible. As the network scales, problems will scale too.
Larger networks demand more results, flexibility, and easy-to-read set of commands.
An IP Address Scanner tool helps you with larger demands. These tools are able to map the entire local network, finds live hosts, and to provide the results of the “arp-a” in a clearer format. Other IP Scanners do not depend on ARP but they operate using repeated ping tests. A Ping Sweep tool lets you ping entire subnets and find live hosts just with one button.
Some other IP Scanners go the extra mile and give more information such as Port number, DNS, DHCP, etc. All of this data is also presented in the most visual and easy-to-read format. They also allow users to save all results and present them in detailed reports.
The best IP Address discovery tools
Our methodology for selecting a third-party tool to scan for IP addresses
We reviewed the market for IP address discovery tools and analyzed options based on the following criteria:
- A service that can be run on demand, on a schedule, or continuously
- Scans of the entire network or the option to limit searches to an address range
- DNS resolution
- Mapping from MAC addresses to IP addresses
- A system that can also provide availability and response time tests
- A free trial that provides a no-cost opportunity to assess the package or a free tool
- Value for money from a system that is offered at a fair price or a free tool that is worth installing
With these selection criteria in mind, we identified a number of network scanners that will discover IP addresses and identify the devices to which they have been allocated by mapping to MAC addresses.
1. SolarWinds Engineer’s Toolset Ping Sweep – FREE TRIAL
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Tested on: Windows & Windows Server
SolarWinds Engineer’s Toolset Ping Sweep is one of more than 60 network management systems in the Engineer’s Toolset. The package provides systems for monitoring networks but it is mainly a bundle of network troubleshooting tools.
Key Features:
- Discover network devices
- Record IP addresses in use
- Scan a range of addresses
- View hostnames
- Get response times
Why do we recommend it?
The Ping Sweep tool is part of the SolarWinds Engineer’s Toolset. This package provides a single dashboard for many tools, so you don’t have to go looking around your desktop to find this or any of the other utilities when you need them. The package is for Windows Server but you can also install it on a Windows PC.
The GUI interface includes a field where the user can enter a range of IP addresses to scan. The field can also take a non-sequential list, and if that list is long, you can write it into a text file and put the path and file name in the IP address range field instead of the actual addresses.
The interface makes the output easy to read and it shows a line for each address in the given range or list. You can select a setting that will restrict the output to only show those addresses that responded. The record for a discovered IP address shows the response time of the Ping test to that node and the utility will also check in the local DNS file to show the hostname for the discovered device.
As well as viewing the results in the Engineer’s Toolset dashboard, you can store results to a text file or a CSV for further analysis. The system doesn’t provide the option to run continuously, so you would use this tool for on-demand address testing. The Engineer’s Toolset also includes facilities for managing DNS and DHCP servers and there are a number of subnetting utilities in the package.
After discovering all devices with the Ping Sweep tool, network managers can switch to the Open Port Scanner to examine which ports are open on each device or run through a list of devices to see all results in one list.
Who is it recommended for?
This is a useful package for network troubleshooting on a large or mid-sized network or for network monitoring on a small network. The Engineer’s Toolset also provides utilities to examine DNS and DHCP servers and it provides other OIP address management utilities. You can also use facilities in the package to check on the ports on each endpoint on your network.
The Engineer’s Toolset is a single package for all 60 utilities, including the Ping Sweep tool. The software package runs on Windows Server or Windows. You can examine the package by accessing a 14-day free trial.
ManageEngine OpUtils combines an IP address manager, a switch port mapper for MAC address discovery, and a port scanner to identify open TCP and UDP ports on all devices. This combination delivers all address-related functions that you will need in order to fully manage your network.
Key Features:
- IP address manager
- Subnet planner
- Identifies abandoned addresses
Why do we recommend it?
We recommend ManageEngine OpUtils for its efficient network management capabilities. OpUtils offers an IP address manager as part of its utility suite, so you can discover all connected devices, and their associated IP addresses, and then manage them from a single console.
The IP address manager is, in itself, a suite of utilities. This group of services includes an IP address scanner. This will discover all of the devices connected to your network and list the IP addresses allocated to them. The IPAM is able to produce IP address reconciliation reports that will enable you to update your native DHCP server in case it fails to notice expired address leases.
The IP address tracker service in the bundle can produce a hierarchical view of your network, enabling you to identify subnets and the allocation of addresses to each. DHCP management tools in the pack let you manage subnet address pools. The switch port mapper identifies each device by MAC address and switch port number. The port scanner in OpUtils lets you see which TCP and UDP ports on each device are open.
OpUtils is available for Windows Server and for Linux.
Who is it recommended for?
ManageEngine OpUtils is recommended for various-sized networks, from SMBs to large enterprises. The solution is designed for any network admin or IT professional within those networks, looking for a complete IP address management solution.
OpUtils is available in a Free version, which includes a port scanner and Ping utilities. Contact the ManageEngine sales team for a quote on the paid version. The paid version of OpUtils can be downloaded as a 30-day free trial.
ManageEngine OUtils Download a 30-day FREE Trial
3. Angry IP Scanner
Angry IP Scanner is one of the most popular scanners on the web, with over 29 million downloads. It is open-source, free, and available for Windows, MacOS, and Linux. It can let you scan your local network or the Internet-facing IP addresses.
Key Features:
- On-demand Ping sweeps
- Tabulated results
- Save to file
Why do we recommend it?
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Angry IP Scanner is recommended for being one of the most used and relied-on open-source tools. If IP address scanning is all you need, Angry IP Scanner is easy to use and quite efficient in scanning both local and Internet-facing IP addresses.
This tool is not only capable of scanning IP addresses but also ports. When you define an IP address range, you can also specify a number of the port, and see if a device in your network is using a specific service (defined by the port). Angry IP Scanner also lets you save all the scan results into multiple formats, such as TXT, XML, CVS, etc.
When you scan, you’ll know what hosts are alive, their response time, hostname, MAC address, etc. If you want even more information, you can extend results by developing Java plugins.
Who is it recommended for?
Angry IP Scanner is recommended for one-off scans of smaller networks. It works very well in uncomplicated situations and small networks where network admins require a fast and simple way to scan networks. Angry IP Scanner does not scale well on larger networks.
Price: Open Source and 100% free.
Download: Get Angry IP from its official site.
IP Address Tracker Tools
Having a map of IP addresses, MAC addresses, used ports, etc, is great for networking inventorying and may help with some troubleshooting cases. But a list can not control and display real-time results.
An IP address Tracker is a good upgrade to our set of tools and commands described so far. It does allow scanning multiple subnets and displaying results, but it also allows you to keep track of one or more IP addresses.
An IP Address Tracker will notice when an IP address is released. This can be either because the device lost connectivity or it changed IP address. It will help you minimize IP addressing conflicts (when two devices are trying to take the same IP) and reduce DNS errors.
MyLAN Viewer
MyLAN Viewer is a NetBIOS and IP address scanner for Windows systems. Just like the IP Scanners shown above, this tool will scan a network and show devices in an easy-to-read format.
Key Features:
- Continuous scans
- Alerts for IP address profile changes
- Device details
Why do we recommend it?
MyLAN Viewer is recommended for its dedicated IP scanning capabilities. It provides advanced IP scanning, including continuous scans, schedules, and alerts for IP address profile changes. Also, if you are looking for a comprehensive network data collection (aside from IP addresses), MyLAN Viewer is a great option.
But MyLANViewer goes beyond, and not only shows computer name, IP, and MAC, but also NIC, OS version, logged users, shared folders, and much more.
This tool is able to track specific IP addresses and show notifications when their state change. With it, you can also keep track of network security by showing port information and detecting rogue DHCP servers. MyLAN Viewer tracks all devices in the subnet including hidden, and displays alerts when new devices enter the network, and others go.
This tool can also display the following metrics as well:
- Display Whois data.
- Perform traceroute.
- Manage “Remote Shutdown and Wake On LAN (WOL)”.
- Monitor wireless networks.
Who is it recommended for?
MyLAN Viewer is recommended for network admins working with Windows-based networks and who need detailed information about connected devices. It does not scale well on large networks, thus it is better to use MyLAN Viewer on smaller networks.
Price: Free, but only available for Windows systems.
Download: Get MyLAN Viewer from its official site.
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IP Address Management (IPAM)
Basic IP Address Scanning should be enough to manage small networks. But when networks scale they depend on multiple subnets and detailed management requirements.
Sometimes large-scale networks have standalone DHCP and DNS Servers in order to assign addresses to multiple subnets. But IP conflicts occur and it is really challenging to manage them manually. An IP Address Management or “IPAM” is a piece of software able to actively control DHCP and DNS. It also gives you the ability to manage multiple subnets.
IP address scanning FAQs
How do I find a network name from an IP address?
To get the network name of a host from an IP address you need to query the DNS server. Open a Command Prompt window and enter nslookup <IP_address> putting in the IP address you have instead of <IP_address>.
How do I identify an unknown device on my network?
To see all of the devices connected to your network, type arp -a in a Command Prompt window. This will show you the allocated IP addresses and the MAC addresses of all connected devices. To get the hostname of each IP address you see in the list, use nslookup <IP_address> putting in the IP address you have instead of <IP_address>.
How can I tell what device is at an IP address?
To get deeper information on devices connected to your network rather than just an IP address or MAC address, use a network monitor that scans for details with SNMP – the SolarWinds Network Performance Monitor is one example.
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