First of all, we recommend that you read our other post entitled “TCP/UDP Ports“. But, what are free port scanner tools?
A port scan learns which ports on a router or firewall are open, and can use this information to find a computer system’s potential weaknesses. A port-scanner tool asks about each port, one at a time. The remote system will respond and say whether a port is open or closed. The person running the port scan would then know which ports are open. A port scanner is an application designed to probe a server or host for open ports.
Port scanner tools may be used by administrators to verify security policies of their networks and by attackers to identify network services running on a host and exploit vulnerabilities. The result of a scan on a port is usually generalized into one of three categories:
- Open or Accepted: The host sent a reply indicating that a service is listening on the port.
- Closed or denied or Not Listening: The host sent a reply indicating that connections will be denied to the port.
- Filtered, Dropped or Blocked: There was no reply from the host.
Port scans can also help detect services running on non-default ports. So, if you’re running an FTP server on port 5001 instead of port 21, the port scan would reveal this. You need to make sure that an unqualified person (actually a hacker) can’t scan your network ports because scanning ports can be the beginning of a network attack. A port scan can help an attacker find a weak point to attack and break into a computer system. Firewalls can be configured to detect port scans and block traffic from the address that’s scanning.
Source: howtogeek.com
Best Free Port Scanner Tools
The main purpose of writing this post is to get acquainted with the best free port scanner tools. Let’s look at some of them.
This free port scanner can be run through a graphic interface or from the command line but it is only available for Windows. You can launch a scan on all of the devices on your network, or change the range setting to get a scan for just a section of the network or just one device. The search setting for port numbers is also given a default value. This default limits the search to well-known ports, but you can override this setting and enter your own range of port numbers. You can also enter a list of non-consecutive port numbers.
You able to focus on just TCP or UDP activity or get both of these protocols checked. You can also add in a Ping check and DNS resolution to a search. Results can be exported to CSV, XML, or Excel format.
This tools has some advantages:
- Saving scan configurations
- Finding devices and retrieves user name, port details and connection history
- Searching on IP address, username, hostname, or MAC address to track endpoints
- Defining a DNS server of your choice
- Finding the current location of a user by performing a search on IP address, hostname, or MAC address
- Locating network ports not currently in use
- Reducing scan run times with multithreading
- View and edit IANA port name definitions
- Identifying network vulnerabilities
Source: solarwinds.com and comparitech.com
This scanner finds all the devices in a targeted scan in a matter of seconds and provides easy access to their shared resources, either through HTTP, HTTPS, and FTP, RDP or Radmin ports and even shared folders. This tool is portable.
This port scanner can only be used on Windows OS. The advantages of this tool include:
- Fast scanning of devices
- Identification of Programs
- Remote access
- Wake-On-LAN and Remote PC shutdown
Source: pcwdld.com and advanced-port-scanner.com
NMap is the acronym for Network Mapper. This free and open-source tool is useful for system administrators, DevOps, and network engineers. It supports Windows, Mac, and Linux platforms.
Features:
- Scanning and discover open ports on specific networks
- Discovering potential hosts
- Detecting the OS name and version with the network details
- Identifying the running apps and their version
- A really strong feature in Nmap is different “Port Scan Types”, such as TCP Connect, TCP SYN Scan.
Source: networkworld.com and nmap.org
Angry IP Scanner is a network scanner that can scan the local network and the Internet. It supports Windows, Mac, and Linux platforms. It is a free and open-source platform and doesn’t require any installation. At its most basic level, Angry IP Scanner will ping the target device/network to confirm that it is alive. It can also resolve hostnames, find the MAC address, and scan ports.
Features:
- Allowing to export results in any format
- Detecting web servers and customize openers
- Extensible with the help of various data fetchers
- Having command-line interface
- Uses the multi-threading approach
- Fast and simple using
- Scanning private or a public range of IP addresses and even
- NetBIOS information of a device
- Able to export the results in different formats such as TXT, CSV, XML, or IP-Port list files
Source: angryip.org
This tool is a lightweight standalone scanner which can check a hundred devices per second. It is only supported by Windows OSs. Free IP Scanner pings the IP (or range of IPs) to see who is alive. It can also translate the host-name to IP (or vice versa), find closed and open ports and get NetBIOS information.
Source: eusing.com and pcwdld.com
It provides much more built-in capabilities. Netcat is tiny but powerful. It supports Linux, FreeBSD, NetBSD, Solaris, and Mac OS. NetCat makes use of a TCP/IP connection to read or write data across network connections.
Features:
- Scanning, listening and forwarding open ports
- Outbound & Inbound connections are accessible to and from any ports
- Connecting to a remote system through any port or service
- TCP or UDP is accessible from any ports
- Creating tunnels with specific network parameters, like source port/interface, listening port/interface and the remote host
- It has advanced usage options like buffered send-mode and hexdump.
- Creating back-doors for easy access to the target
- Transfer files from the target
Source: softwaretestinghelp.com
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