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@@ -0,0 +1,285 @@ +1. Prerequisites +---------------- + +A C compiler. Any C89 or better compiler that supports variadic macros +should work. Where supported, configure will attempt to enable the +compiler's run-time integrity checking options. Some notes about +specific compilers: + - clang: -ftrapv and -sanitize=integer require the compiler-rt runtime + (CC=clang LDFLAGS=--rtlib=compiler-rt ./configure) + +To support Privilege Separation (which is now required) you will need +to create the user, group and directory used by sshd for privilege +separation. See README.privsep for details. + + +The remaining items are optional. + +A working installation of zlib: +Zlib 1.1.4 or 1.2.1.2 or greater (earlier 1.2.x versions have problems): +https://zlib.net/ + +libcrypto from either of LibreSSL or OpenSSL. Building without libcrypto +is supported but severely restricts the available ciphers and algorithms. + - LibreSSL (https://www.libressl.org/) + - OpenSSL (https://www.openssl.org) with any of the following versions: + - 1.0.x >= 1.0.1 or 1.1.0 >= 1.1.0g or any 1.1.1 + +Note that due to a bug in EVP_CipherInit OpenSSL 1.1 versions prior to +1.1.0g can't be used. + +LibreSSL/OpenSSL should be compiled as a position-independent library +(i.e. -fPIC, eg by configuring OpenSSL as "./config [options] -fPIC" +or LibreSSL as "CFLAGS=-fPIC ./configure") otherwise OpenSSH will not +be able to link with it. If you must use a non-position-independent +libcrypto, then you may need to configure OpenSSH --without-pie. + +If you build either from source, running the OpenSSL self-test ("make +tests") or the LibreSSL equivalent ("make check") and ensuring that all +tests pass is strongly recommended. + +NB. If you operating system supports /dev/random, you should configure +libcrypto (LibreSSL/OpenSSL) to use it. OpenSSH relies on libcrypto's +direct support of /dev/random, or failing that, either prngd or egd. + +PRNGD: + +If your system lacks kernel-based random collection, the use of Lutz +Jaenicke's PRNGd is recommended. It requires that libcrypto be configured +to support it. + +http://prngd.sourceforge.net/ + +EGD: + +The Entropy Gathering Daemon (EGD) supports the same interface as prngd. +It also supported only if libcrypto is configured to support it. + +http://egd.sourceforge.net/ + +PAM: + +OpenSSH can utilise Pluggable Authentication Modules (PAM) if your +system supports it. PAM is standard most Linux distributions, Solaris, +HP-UX 11, AIX >= 5.2, FreeBSD, NetBSD and Mac OS X. + +Information about the various PAM implementations are available: + +Solaris PAM: http://www.sun.com/software/solaris/pam/ +Linux PAM: http://www.kernel.org/pub/linux/libs/pam/ +OpenPAM: http://www.openpam.org/ + +If you wish to build the GNOME passphrase requester, you will need the GNOME +libraries and headers. + +GNOME: +http://www.gnome.org/ + +Alternatively, Jim Knoble <jmknoble@pobox.com> has written an excellent X11 +passphrase requester. This is maintained separately at: + +http://www.jmknoble.net/software/x11-ssh-askpass/ + +LibEdit: + +sftp supports command-line editing via NetBSD's libedit. If your platform +has it available natively you can use that, alternatively you might try +these multi-platform ports: + +http://www.thrysoee.dk/editline/ +http://sourceforge.net/projects/libedit/ + +LDNS: + +LDNS is a DNS BSD-licensed resolver library which supports DNSSEC. + +http://nlnetlabs.nl/projects/ldns/ + +Autoconf: + +If you modify configure.ac or configure doesn't exist (eg if you checked +the code out of git yourself) then you will need autoconf-2.69 and +automake-1.16.1 to rebuild the automatically generated files by running +"autoreconf". Earlier versions may also work but this is not guaranteed. + +http://www.gnu.org/software/autoconf/ +http://www.gnu.org/software/automake/ + +Basic Security Module (BSM): + +Native BSM support is known to exist in Solaris from at least 2.5.1, +FreeBSD 6.1 and OS X. Alternatively, you may use the OpenBSM +implementation (http://www.openbsm.org). + +makedepend: + +https://www.x.org/archive/individual/util/ + +If you are making significant changes to the code you may need to rebuild +the dependency (.depend) file using "make depend", which requires the +"makedepend" tool from the X11 distribution. + +libfido2: + +libfido2 allows the use of hardware security keys over USB. libfido2 +in turn depends on libcbor. libfido2 >= 1.5.0 is strongly recommended. +Limited functionality is possible with earlier libfido2 versions. + +https://github.com/Yubico/libfido2 +https://github.com/pjk/libcbor + + +2. Building / Installation +-------------------------- + +To install OpenSSH with default options: + +./configure +make +make install + +This will install the OpenSSH binaries in /usr/local/bin, configuration files +in /usr/local/etc, the server in /usr/local/sbin, etc. To specify a different +installation prefix, use the --prefix option to configure: + +./configure --prefix=/opt +make +make install + +Will install OpenSSH in /opt/{bin,etc,lib,sbin}. You can also override +specific paths, for example: + +./configure --prefix=/opt --sysconfdir=/etc/ssh +make +make install + +This will install the binaries in /opt/{bin,lib,sbin}, but will place the +configuration files in /etc/ssh. + +If you are using PAM, you may need to manually install a PAM control +file as "/etc/pam.d/sshd" (or wherever your system prefers to keep +them). Note that the service name used to start PAM is __progname, +which is the basename of the path of your sshd (e.g., the service name +for /usr/sbin/osshd will be osshd). If you have renamed your sshd +executable, your PAM configuration may need to be modified. + +A generic PAM configuration is included as "contrib/sshd.pam.generic", +you may need to edit it before using it on your system. If you are +using a recent version of Red Hat Linux, the config file in +contrib/redhat/sshd.pam should be more useful. Failure to install a +valid PAM file may result in an inability to use password +authentication. On HP-UX 11 and Solaris, the standard /etc/pam.conf +configuration will work with sshd (sshd will match the other service +name). + +There are a few other options to the configure script: + +--with-audit=[module] enable additional auditing via the specified module. +Currently, drivers for "debug" (additional info via syslog) and "bsm" +(Sun's Basic Security Module) are supported. + +--with-pam enables PAM support. If PAM support is compiled in, it must +also be enabled in sshd_config (refer to the UsePAM directive). + +--with-prngd-socket=/some/file allows you to enable EGD or PRNGD +support and to specify a PRNGd socket. Use this if your Unix lacks +/dev/random. + +--with-prngd-port=portnum allows you to enable EGD or PRNGD support +and to specify a EGD localhost TCP port. Use this if your Unix lacks +/dev/random. + +--with-lastlog=FILE will specify the location of the lastlog file. +./configure searches a few locations for lastlog, but may not find +it if lastlog is installed in a different place. + +--without-lastlog will disable lastlog support entirely. + +--with-osfsia, --without-osfsia will enable or disable OSF1's Security +Integration Architecture. The default for OSF1 machines is enable. + +--with-utmpx enables utmpx support. utmpx support is automatic for +some platforms. + +--without-shadow disables shadow password support. + +--with-ipaddr-display forces the use of a numeric IP address in the +$DISPLAY environment variable. Some broken systems need this. + +--with-default-path=PATH allows you to specify a default $PATH for sessions +started by sshd. This replaces the standard path entirely. + +--with-pid-dir=PATH specifies the directory in which the sshd.pid file is +created. + +--with-xauth=PATH specifies the location of the xauth binary + +--with-ssl-dir=DIR allows you to specify where your Libre/OpenSSL +libraries are installed. + +--with-ssl-engine enables Libre/OpenSSL's (hardware) ENGINE support + +--without-openssl builds without using OpenSSL. Only a subset of ciphers +and algorithms are supported in this configuration. + +--without-zlib builds without zlib. This disables the Compression option. + +--with-4in6 Check for IPv4 in IPv6 mapped addresses and convert them to +real (AF_INET) IPv4 addresses. Works around some quirks on Linux. + +If you need to pass special options to the compiler or linker, you +can specify these as environment variables before running ./configure. +For example: + +CC="/usr/foo/cc" CFLAGS="-O" LDFLAGS="-s" LIBS="-lrubbish" ./configure + +3. Configuration +---------------- + +The runtime configuration files are installed by in ${prefix}/etc or +whatever you specified as your --sysconfdir (/usr/local/etc by default). + +The default configuration should be instantly usable, though you should +review it to ensure that it matches your security requirements. + +To generate a host key, run "make host-key". Alternately you can do so +manually using the following commands: + + ssh-keygen -t [type] -f /etc/ssh/ssh_host_key -N "" + +for each of the types you wish to generate (rsa, dsa or ecdsa) or + + ssh-keygen -A + +to generate keys for all supported types. + +Replacing /etc/ssh with the correct path to the configuration directory. +(${prefix}/etc or whatever you specified with --sysconfdir during +configuration). + +If you have configured OpenSSH with EGD/prngd support, ensure that EGD or +prngd is running and has collected some entropy first. + +For more information on configuration, please refer to the manual pages +for sshd, ssh and ssh-agent. + +4. (Optional) Send survey +------------------------- + +$ make survey +[check the contents of the file "survey" to ensure there's no information +that you consider sensitive] +$ make send-survey + +This will send configuration information for the currently configured +host to a survey address. This will help determine which configurations +are actually in use, and what valid combinations of configure options +exist. The raw data is available only to the OpenSSH developers, however +summary data may be published. + +5. Problems? +------------ + +If you experience problems compiling, installing or running OpenSSH, +please refer to the "reporting bugs" section of the webpage at +https://www.openssh.com/ |