Nmap vs Nessus - Which one is better?

Nessus is mainly used as an IT infrastructure vulnerability assessment tool while Nmap is an open-source and most popular port scanner tool. Both tools are used remotely and provide a list of possible vulnerabilities of the target system. This article covers both Nessus and Nmap tools, here we compare the functionalities offered by both tools. Click Here if you are interested in comparing OpenVAS vs Nessus, both are vulnerability scanner tools.

Comparison of tools based on security functionality available in Nmap and Nessus

Functionality	Nmap	Nessus
Installation	Easy	Easy
Port scanning	Available	Available
Vulnerability Scripts	Available	Available
Cost	Free	Both Free and Pro
Configuration Assessment	Very Limited	Available
Ease of Use	Medium	Easy
Customer Support	Not Available	Available
Speed	Faster	Slower than Nmap

Installation

Both Nessus and Nmap tools are easy to install and you can easily install both tools by following the official guide. Remember, you need an official id to register for Nessus Professional tool and it is available for a 7-day free trial. After the expiration of 7 days trial, you can use the community edition of the tool freely. Nmap is pre-installed on Kali Linux. A GUI version of Nmap is also available.

Nessus tool updates plugins once you start the first time by using http://127.0.0.1:8834/

Port scanning

Both tools provide port scanning security functionality and provide great details while reporting open ports of the target system. But if you talk specifically, Nmap is a tool used for only port and service scanning and Nessus has a whole list of security functionality including port scanning. Port scanning is one such functionality available in the Nessus tool.

Vulnerability scripts

In this discussion, vulnerability scripts is the term used to denote scripts available in a database of tools that help in finding known vulnerabilities automatically. Both Nmap and Nessus have vulnerability scripts and you can use them very easily against the target system. Nessus scripts are available that are called plugins that identify known vulnerabilities. Nmap also has a scripting engine and a lot of scripts available at location /usr/share/nmap/scripts. You can select scripts and run them whenever required.

Cost

Nessus tool is available in both community and professional editions. Nessus community edition is free but has very little functionality. Nessus Professional is not a much expensive tool and different subscription plans are available for around $3000 a year. Nmap is free and you can use this tool without paying a single penny.

Configuration Assessment

Nessus is popular and very effective for doing configuration assessments based on available international (e.g. Computer of Internet Security(CIS)) benchmarks. This tool is very effective in configuration assessment activity and is the number one choice for security auditors. Nmap is able to run some vulnerability scripts but it is not equivalent to the whole configuration assessment activity as performed by Nessus.

Ease of Use

Nessus comes with a nice GUI (Graphical User Interface) and new users can also run scanning for target very easily. Just need to provide target details such as the name of the scan, target IP, plugin selection for the type of scan, etc. Nessus also supports concurrency as you can run multiple scans at the same time and stop, resume scan options are also available. Nmap tool is available both in the command line and GUI. But most security researchers use this tool in the command line. Below is the command to run a Nmap basic scan:

nmap <Target-IP>

Customer Support

Nessus is owned by Tenable and has a customer support team that helps to diagnose issues related to problems. As stated earlier, Nmap is free and open-source hence no customer support is available. Although, a big community is there to resolve issues and develop new scripts to identify new vulnerabilities.

Speed

Nessus is a slow tool if you compare it with the Nmap tool. To start the Nessus scan, you need to fill in whole details such as IP address, select plugins, etc. against the target. Nmap is very fast and you will scan by just typing the Nmap with an IP address.

Conclusion

Nessus and Nmap, are both tools that are broadly used by the information security community. Nessus is a more complete tool and is used as a defacto tool by professional security auditing agencies. Nmap tool is more used to identify open ports and services to identify the specific types of vulnerabilities. Now, which one is better? If you are performing official audits and you need to submit reports to clients, Nessus is better as this tool gives clean reports for different security compliance. This tool also suggests mitigation measures that are missing in the Nmap tool. Nmap is a quick tool that provides some security misconfigurations and vulnerabilities of the target.