Introduction to libidn

libidn is a package designed for internationalized string handling based on the Stringprep, Punycode and IDNA specifications defined by the Internet Engineering Task Force (IETF) Internationalized Domain Names (IDN) working group, used for internationalized domain names. This is useful for converting data from the system's native representation into UTF-8, transforming Unicode strings into ASCII strings, allowing applications to use certain ASCII name labels (beginning with a special prefix) to represent non-ASCII name labels, and converting entire domain names to and from the ASCII Compatible Encoding (ACE) form.

This package is known to build and work properly using an LFS 12.1 platform.

Package Information

libidn Dependencies


Emacs-29.2, GTK-Doc-1.33.2, OpenJDK-21.0.2, Valgrind-3.22.0, and Mono

Installation of libidn

Install libidn by running the following commands:

./configure --prefix=/usr --disable-static &&

To test the results, run:

pushd tests  &&
  make check &&

Now, as the root user:

make install &&

find doc -name "Makefile*" -delete            &&
rm -rf -v doc/{gdoc,idn.1,stamp-vti,man,texi} &&
mkdir -v       /usr/share/doc/libidn-1.42     &&
cp -r -v doc/* /usr/share/doc/libidn-1.42

Command Explanations

--disable-static: This switch prevents installation of static versions of the libraries.

--enable-gtk-doc: Use this parameter if GTK-Doc is installed and you wish to rebuild and install the API documentation.

--enable-java: Use this switch to enable building the Java implementation of libidn. Note that OpenJDK-21.0.2 must be installed to use this option.


Installed Program: idn
Installed Library:
Installed Directories: /usr/share/doc/libidn-1.42 and /usr/share/gtk-doc/html/libidn

Short Descriptions


is a command line interface to the internationalized domain name library

contains a generic Stringprep implementation that does Unicode 3.2 NFKC normalization, mapping and prohibition of characters, and bidirectional character handling. Profiles for Nameprep, iSCSI, SASL and XMPP are included as well as support for Punycode and ASCII Compatible Encoding (ACE) via IDNA. A mechanism to define Top-Level Domain (TLD) specific validation tables, and to compare strings against those tables, as well as default tables for some TLDs are included