Halifax has denied this, arguing that port scans help gather evidence of malware infections on customers` systems. The scans are legal, Halifax Moore said in response to a complaint he filed last month about the matter. Eventually, the criminal court came to the same conclusion and all charges were dropped. Although Scott was eventually confirmed, he suffered six-figure bills and endured stressful years of struggle in the court system. On the bright side, after spending so much time educating his lawyers on the technical issues involved, Scott launched a successful court services firm. The relationship between port analysis and the UK`s Computer Misuse Act 1990 has always been tense. Does scanning ports without consent constitute unauthorized access under section 1 of the Computer Misuse Act or not? Some experts conclude that network analysis activities “are almost never acceptable without the explicit permission of the target network managers” (2). Others argue that “some analyses of external systems should be lawful even without explicit permission” (3). The fact that the developer of the popular network analysis tool nmap wrote more than 3,500 words weighing the various legal dilemmas raised by port analysis (4) is perhaps sufficient evidence of the ambiguity created by the Computer Misuse Act. Many of the legal issues mirror those raised by threat intelligence research. But the fact that port scanning activities still take place while security research is discouraged from doing a lot of threat research leaves a bitter taste of “one rule for them, one rule for others.” For testing purposes, you are allowed to analyze the Host-scanme.nmap.org. You may have noticed that it has already been used in several examples.
Note that this permission only includes scanning with Nmap and not testing exploits or denial of service attacks. To save bandwidth, run no more than a dozen scans per day on this host. If this free scan target service is abused, it will be removed and Nmap will report Failed to resolve given hostname/IP: scanme.nmap.org. Ok, so it`s illegal in the UK, how can I practice and learn? So I`m new to nmap. I watched a few tutorial videos and they came with warnings that some things on nmap are illegal, and be careful. That is why I would like more clarity on what to avoid. and what sanctions to expect. When used correctly, Nmap protects your network from intruders.
But if misused, Nmap (in rare cases) can result in lawsuits, fires, bans, imprisonment, or bans by your ISP. Reduce your risk by reading this legal guide before you start Nmap. For example, if I did an nmap analysis of, say, www.twitter.com, is that illegal? “At the end of the day, we can`t have it anyway,” Moore told El Reg. “It`s either legal to scan someone without consent or with their consent, but without malicious intent, or it`s illegal and Halifax has to change its delivery to only filter customers, not visitors.” British security expert Kevin Beaumont added: “I would wonder if it was really illegal if there was no malicious intent. Half of the infosec services would be illegal (Shodan, Censys, etc.). IRC networks check the connection, Xbox does, PlayStation, etc.” NmapFE, originally written by Kanchan, was the official Nmap GUI for Nmap versions 2.2 to 4.22.  For Nmap 4.50 (originally in the 4.22SOC development series), NmapFE has been replaced by Zenmap, a new official UMIT-based graphical user interface developed by Adriano Monteiro Marques. While Moulton is a good example (if not a precedent), various courts or situations could still lead to worse outcomes.
These dangerous laws are based on the intent of the author or user of the tool, which is subjective and difficult to guess. Nmap was designed to secure the internet, but I would hate to be arrested and forced to defend my intentions in front of a judge and jury, especially in a foreign country like Germany where I don`t even speak the language. These laws are unlikely to affect tools as widely used and popular as Nmap, but they do act as a deterrent to smaller tools and those that are more commonly abused by computer criminals (e.g., operating executives). The best way to think about scanning ports is the same as checking locks on different doors. It is not illegal to go to your neighbours` homes and check their doors to see if they are locked or not; Legality is only an option if you actually enter the house. Scanning works in the same way. To summarize this entire section, the question of whether port analysis is legal does not have a simple answer. I cannot say unequivocally, “Port analysis is never a crime,” as much as I would like to do. Laws differ considerably from jurisdiction to jurisdiction, and cases depend on their particular details. Even when the facts are almost identical, different judges and prosecutors do not always interpret them in the same way. I can only urge caution and repeat the above suggestions. Even if an ISP does not explicitly prohibit scanning of unauthorized ports, it could argue that an “anti-piracy” provision applies.
Of course, this does not make port analysis illegal. Many activities that are completely legal and (in the US) constitutionally protected are prohibited by ISPs. For example, the AUP cited above also prohibits users from “transmitting, storing, or posting any information or material that a reasonable person might consider offensive, offensive, indecent, pornographic, etc. embarrassing, disturbing, vulgar, hateful, racially or ethnically offensive, or otherwise inappropriate, whether such material or its dissemination is unlawful. In other words, some ISPs prohibit any behavior that might offend or upset someone. Randomizing other people`s networks has this potential. If you decide to do such controversial analyses, never do it from work, school, or any other provider who has substantial control over your well-being. Use a commercial broadband or mobile operator instead. Losing the DSL connection and changing carriers is a minor nuisance, but it`s infinitely better than being banned or fired.
Regardless of the legal status of port scanning, ISP accounts will continue to be terminated if many complaints are generated. The best way to avoid ISP abuse reports or civil/criminal charges is not to annoy the target network administrators at all. Here are some practical suggestions: It depends on the laws of your country, I think. It would make sense if nothing nmap is capable of is illegal.  An excellent article by lawyer Ethan Preston on the subject is available at grove.ufl.edu/~techlaw/vol6/issue1/preston.html. He also wrote an excellent article on the legal risks of publishing security information and exploits to www.mcandl.com/computer-security.html. Although legal cases involving port scanning (without tracking hacking attacks) are rare, they do happen. One of the most notable cases involved a man named Scott Moulton who had an ongoing consulting contract to maintain the 911 emergency system in Cherokee County, Georgia.