SYN scan is the default and most popular scan option for good reason. It can be performed quickly, scanning thousands of ports per second on a fast network not hampered by intrusive firewalls. SYN scan is relatively unobtrusive and stealthy, since it never completes TCP connections. It also works against any compliant TCP stack rather than depending on idiosyncrasies of specific platforms as Nmap's FIN/NULL/Xmas, Maimon and idle scans do. It also allows clear, reliable differentiation between op...
This file was originally based off the IANA assigned ports list at http://www.iana.org/assignments/port-numbers, though many other ports have been added over the years. The IANA does not track trojans, worms and the like, yet discovering them is important for many Nmap users. The grammar of this file is pretty simple. There are three whitespace-separated columns. The first is the service name or abbreviation, as seen in the SERVICE column of Nmap output. The second column gives the port number and protocol, separated by a slash. That syntax is ...
Probe Response, Assigned State ; Any UDP response from target port (unusual), open ; No response received (even after retransmissions), open filtered ; ICMP port unreachable error (type 3, code 3), closed
As a novice performing automotive repair, I can struggle for hours trying to fit my rudimentary tools (hammer, duct tape, wrench, etc.) to the task at hand. When I fail miserably and tow my jalopy to a real mechanic, he invariably fishes around in a huge tool chest until pulling out the perfect gizmo which makes the job seem effortless. The art of port scanning is similar. Experts understand the dozens of scan techniques and choose the appropriate one (or combination) for a given task. Inexperie...
Probe Response, Assigned State ; TCP RST response, unfiltered ; No response received (even after retransmissions), filtered ; ICMP unreachable error (type 3, code 1, 2, 3, 9, 10, or 13), filtered
The six port states recognized by Nmap ; closed · A closed port is accessible (it receives and responds to Nmap probe packets), but there is no application listening on it. They can be helpful in showing that a host is up on an IP address (host discovery, or ping scanning), and as part of OS detection. Because closed ports are reachable, it may be worth scanning later in case some open up. Administrators may want to consider blocking such ports with a firewall. Then they would appear in the filtered state, discussed next. filtered · Nmap cann ...
Legal Notices ; Nmap Copyright and Licensing ; Creative Commons License for this Nmap Guide ; Source Code Availability and Community Contributions
Nmap does not have an option for saving scan results in HTML, however it is possible to convert XML output to HTML automatically. An Nmap XML output file usually contains a reference to an XSL stylesheet called nmap.xsl that describes how the transformation takes place. The XML processing instruction that says where the stylesheet can be found will look something like · The exact location may be different depending on the platform and how Nmap was configured. Such a stylesheet reference will work fine when viewing scan results on the same mach ...
Table of Contents ; Obtaining Nmap from the Subversion (SVN) Repository ; Linux/Unix Compilation and Installation from Source Code ; Updating Red Hat, Fedora, Mandrake, and Yellow Dog Linux with Yum ; Installing the Nmap zip binaries
One of Nmap's best-known features is remote OS detection using TCP/IP stack fingerprinting. Nmap sends a series of TCP and UDP packets to the remote host and examines practically every bit in the responses. After performing dozens of tests such as TCP ISN sampling, TCP options support and ordering, IP ID sampling, and the initial window size check, Nmap compares the results to its nmap-os-db database of more than 2,600 known OS fingerprints and prints out the OS details if there is a match. Each fingerprint includes a freeform textual descripti ...