This option, which is standard to the configure scripts of most software, determines where Nmap and its components are installed. By default, the prefix is /usr/local, meaning that nmap is installed in /usr/local/bin, the man page (nmap.1) is installed in /usr/local/man/man1, and the data files (nmap-os-db, nmap-services, nmap-service-probes, etc.) are installed under /usr/local/share/nmap. If you only wish to change the path of certain components, use the options --bindir, --datadir, and/or --mandir. An example usage of --prefix would be to install Nmap in my account as an unprivileged user. I would run ./configure --prefix=</home/fyodor>. Nmap creates subdirectories like /home/fyodor/man/man1 in the install stage if they do not already exist.

Some distributions ship with user OpenSSL libraries that allow running programs, but not the developer files needed to compile them. Without these developer packages, Nmap will not have OpenSSL support. On Debian-based systems, install the libssl-dev package. On Red Hat–based systems, install openssl-devel.

Nmap uses the Libpcap library for capturing raw IP packets. Nmap normally looks for an existing copy of Libpcap on your system and uses that if the version number and platform is appropriate. Otherwise Nmap includes its own recent copy of Libpcap (with some local modifications described in libpcap/NMAP_MODIFICATIONS in the Nmap source directory). If you wish to force Nmap to link with your own Libpcap, pass the option --with-libpcap=<directoryname> to configure. Nmap then expects the Libpcap library to be in <directoryname>/lib/libpcap.a and the include files to be in <directoryname>/include. Nmap will always use the version of Libpcap included in its tarball if you specify --with-libpcap=included.

PCRE is a Perl-compatible regular expression library available from http://www.pcre.org. Nmap normally looks for a copy on your system, and then falls back to its own copy if that fails. If your PCRE library is not in your compiler's standard search path, Nmap probably will not find it. In that case you can tell Nmap where it can be found by specifying the option --with-libpcre=<directoryname> to configure. Nmap then expects the library files to be in <directoryname>/lib and the include files to be in <directoryname>/include. In some cases, you may wish to use the PCRE libraries included with Nmap in preference to those already on your system. In that case, specify --with-libpcre=included.

Libdnet is an excellent networking library that Nmap uses for sending raw ethernet frames. The version in the Nmap tree is heavily modified (particularly the Windows code), so the default is to use that included version. If you wish to use a version already installed on your system instead, specify --with-libdnet=<directoryname>. Nmap then expects the library files to be in <directoryname>/lib and the include files to be in <directoryname>/include.

This simple option tells Nmap to look in /usr/local/lib and /usr/local/include for important library and header files. This should never be necessary, except that some people put such libraries in /usr/local without configuring their compiler to find them. If you are one of those people, use this option.

Extra options to pass to the C compiler, C++ compiler, and linker, respectively. Because parts of Nmap are written in C and others in C++, it's best to use both CFLAGS and CXXFLAGS if you're going to use one of them.

By default, make install will install all the available translations of the Nmap man page in addition to the English one. The LINGUAS environment variable can control which translations are installed. Its value should be a space-separated list of ISO language codes. For example, to install only the French and German translations, you might run LINGUAS="fr de" make install. To disable the installation of all translations, run configure with the --disable-nls option or set LINGUAS to the empty string.

Check https://nmap.org/download.html to make sure you are using the latest version of Nmap. The problem may have already been fixed.

Scroll up in the output screen and examine the error messages given when commands fail. It is often best to find the first error message, as that often causes a cascade of further errors. Read the error message carefully, as it could indicate a system problem such as low disk space or a broken compiler. Users with programming skills may be able to resolve a wider range of problems themselves. If you make code changes to fix the problem, please send a patch (created with diff -uw <oldfile> <newfile>) and any details about your problem and platform to nmap-dev as described in the section called “Bugs”. Integrating the change into the base Nmap distribution allows many other users to benefit, and prevents you from having to make the changes with each new Nmap version.

Try searching for the exact error message on Google or other search engines. You might also want to browse recent activity on the Nmap development (nmap-dev) list—archives and a search interface are available at https://seclists.org.

If none of your research leads to a solution, try sending a report to the Nmap development (nmap-dev) mailing list, as described in the section called “Bugs”.