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diff --git a/doc/installation.adoc b/doc/installation.adoc new file mode 100644 index 0000000..eea9088 --- /dev/null +++ b/doc/installation.adoc @@ -0,0 +1,217 @@ +// This file is part of chrony +// +// Copyright (C) Richard P. Curnow 1997-2003 +// Copyright (C) Miroslav Lichvar 2009-2016 +// +// This program is free software; you can redistribute it and/or modify +// it under the terms of version 2 of the GNU General Public License as +// published by the Free Software Foundation. +// +// This program is distributed in the hope that it will be useful, but +// WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +// General Public License for more details. +// +// You should have received a copy of the GNU General Public License along +// with this program; if not, write to the Free Software Foundation, Inc., +// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + += Installation + +The software is distributed as source code which has to be compiled. The source +code is supplied in the form of a gzipped tar file, which unpacks to a +subdirectory identifying the name and version of the program. + +After unpacking the source code, change directory into it, and type + +---- +./configure +---- + +This is a shell script that automatically determines the system type. There is +an optional parameter `--prefix`, which indicates the directory tree where the +software should be installed. For example, + +---- +./configure --prefix=/opt/free +---- + +will install the `chronyd` daemon into `/opt/free/sbin` and the `chronyc` +control program into `/opt/free/bin`. The default value for the prefix is +`/usr/local`. + +The `configure` script assumes you want to use `gcc` as your compiler. If you +want to use a different compiler, you can configure this way: + +---- +CC=cc ./configure --prefix=/opt/free +---- + +for Bourne-family shells, or + +---- +setenv CC cc +setenv CFLAGS -O +./configure --prefix=/opt/free +---- + +for C-family shells. + +If the software cannot (yet) be built on your system, an error message will be +shown. Otherwise, `Makefile` will be generated. + +On Linux, if development files for the libcap library are available, `chronyd` +will be built with support for dropping root privileges. On other systems no +extra library is needed. The default user which `chronyd` should run as can be +specified with the `--with-user` option of the `configure` script. + +If development files for the POSIX threads library are available, `chronyd` +will be built with support for asynchronous resolving of hostnames specified in +the `server`, `peer`, and `pool` directives. This allows `chronyd` operating as +a server to respond to client requests when resolving a hostname. If you don't +want to enable the support, specify the `--disable-asyncdns` flag to +`configure`. + +If development files for the https://www.lysator.liu.se/~nisse/nettle/[Nettle], +https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS[NSS], or +http://www.libtom.net/LibTomCrypt/[libtomcrypt] library are available, +`chronyd` will be built with support for other cryptographic hash functions +than MD5, which can be used for NTP authentication with a symmetric key. If you +don't want to enable the support, specify the `--disable-sechash` flag to +`configure`. + +If development files for the editline or readline library are available, +`chronyc` will be built with line editing support. If you don't want this, +specify the `--disable-readline` flag to `configure`. + +If a `timepps.h` header is available (e.g. from the +http://linuxpps.org[LinuxPPS project]), `chronyd` will be built with PPS API +reference clock driver. If the header is installed in a location that isn't +normally searched by the compiler, you can add it to the searched locations by +setting the `CPPFLAGS` variable to `-I/path/to/timepps`. + +The `--help` option can be specified to `configure` to print all options +supported by the script. + +Now type + +---- +make +---- + +to build the programs. + +If you want to build the manual in HTML, type + +---- +make docs +---- + +Once the programs have been successfully compiled, they need to be installed in +their target locations. This step normally needs to be performed by the +superuser, and requires the following command to be entered. + +---- +make install +---- + +This will install the binaries and man pages. + +To install the HTML version of the manual, enter the command + +---- +make install-docs +---- + +Now that the software is successfully installed, the next step is to set up a +configuration file. The default location of the file is _/etc/chrony.conf_. +Several examples of configuration with comments are included in the examples +directory. Suppose you want to use public NTP servers from the pool.ntp.org +project as your time reference. A minimal useful configuration file could be + +---- +pool pool.ntp.org iburst +makestep 1.0 3 +rtcsync +---- + +Then, `chronyd` can be run. For security reasons, it's recommended to create an +unprivileged user for `chronyd` and specify it with the `-u` command-line +option or the `user` directive in the configuration file, or set the default +user with the `--with-user` configure option before building. + +== Support for system call filtering + +`chronyd` can be built with support for the Linux secure computing (seccomp) +facility. This requires development files for the +https://github.com/seccomp/libseccomp[libseccomp] library and the +`--enable-scfilter` option specified to `configure`. The `-F` option of +`chronyd` will enable a system call filter, which should significantly reduce +the kernel attack surface and possibly prevent kernel exploits from `chronyd` +if it is compromised. + +== Support for line editing libraries + +`chronyc` can be built with support for line editing, this allows you to use +the cursor keys to replay and edit old commands. Two libraries are supported +which provide such functionality, editline and GNU readline. + +Please note that readline since version 6.0 is licensed under GPLv3+ which is +incompatible with chrony's license GPLv2. You should use editline instead if +you don't want to use older readline versions. + +The `configure` script will automatically enable the line editing support if +one of the supported libraries is available. If they are both available, the +editline library will be used. + +If you don't want to use it (in which case `chronyc` will use a minimal command +line interface), invoke `configure` like this: + +---- +./configure --disable-readline other-options... +---- + +If you have editline, readline or ncurses installed in locations that aren't +normally searched by the compiler and linker, you need to use extra options: + +`--with-readline-includes=directory_name`:: + This defines the name of the directory above the one where `readline.h` is. + `readline.h` is assumed to be in `editline` or `readline` subdirectory of the + named directory. + +`--with-readline-library=directory_name`:: + This defines the directory containing the `libedit.a` or `libedit.so` file, + or `libreadline.a` or `libreadline.so` file. + +`--with-ncurses-library=directory_name`:: + This defines the directory containing the `libncurses.a` or `libncurses.so` + file. + +== Extra options for package builders + +The `configure` and `make` procedures have some extra options that may be +useful if you are building a distribution package for `chrony`. + +The `--mandir=DIR` option to `configure` specifies an installation directory +for the man pages. This overrides the `man` subdirectory of the argument to the +`--prefix` option. + +---- +./configure --prefix=/usr --mandir=/usr/share/man +---- + +to set both options together. + +The final option is the `DESTDIR` option to the `make` command. For example, +you could use the commands + +---- +./configure --prefix=/usr --mandir=/usr/share/man +make all docs +make install DESTDIR=./tmp +cd tmp +tar cvf - . | gzip -9 > chrony.tar.gz +---- + +to build a package. When untarred within the root directory, this will install +the files to the intended final locations. |