11. Prerequisites 2---------------- 3 4A C compiler. Any C89 or better compiler should work. Where supported, 5configure will attempt to enable the compiler's run-time integrity checking 6options. Some notes about specific compilers: 7 - clang: -ftrapv and -sanitize=integer require the compiler-rt runtime 8 (CC=clang LDFLAGS=--rtlib=compiler-rt ./configure) 9 10To support Privilege Separation (which is now required) you will need 11to create the user, group and directory used by sshd for privilege 12separation. See README.privsep for details. 13 14 15The remaining items are optional. 16 17A working installation of zlib: 18Zlib 1.1.4 or 1.2.1.2 or greater (earlier 1.2.x versions have problems): 19http://www.gzip.org/zlib/ 20 21libcrypto from either of LibreSSL or OpenSSL. Building without libcrypto 22is supported but severely restricts the available ciphers and algorithms. 23 - LibreSSL (https://www.libressl.org/) 24 - OpenSSL (https://www.openssl.org) with any of the following versions: 25 - 1.0.x >= 1.0.1 or 1.1.0 >= 1.1.0g or any 1.1.1 26 27Note that due to a bug in EVP_CipherInit OpenSSL 1.1 versions prior to 281.1.0g can't be used. 29 30LibreSSL/OpenSSL should be compiled as a position-independent library 31(i.e. -fPIC, eg by configuring OpenSSL as "./config [options] -fPIC" 32or LibreSSL as "CFLAGS=-fPIC ./configure") otherwise OpenSSH will not 33be able to link with it. If you must use a non-position-independent 34libcrypto, then you may need to configure OpenSSH --without-pie. 35 36If you build either from source, running the OpenSSL self-test ("make 37tests") or the LibreSSL equivalent ("make check") and ensuring that all 38tests pass is strongly recommended. 39 40NB. If you operating system supports /dev/random, you should configure 41libcrypto (LibreSSL/OpenSSL) to use it. OpenSSH relies on libcrypto's 42direct support of /dev/random, or failing that, either prngd or egd. 43 44PRNGD: 45 46If your system lacks kernel-based random collection, the use of Lutz 47Jaenicke's PRNGd is recommended. It requires that libcrypto be configured 48to support it. 49 50http://prngd.sourceforge.net/ 51 52EGD: 53 54The Entropy Gathering Daemon (EGD) supports the same interface as prngd. 55It also supported only if libcrypto is configured to support it. 56 57http://egd.sourceforge.net/ 58 59PAM: 60 61OpenSSH can utilise Pluggable Authentication Modules (PAM) if your 62system supports it. PAM is standard most Linux distributions, Solaris, 63HP-UX 11, AIX >= 5.2, FreeBSD, NetBSD and Mac OS X. 64 65Information about the various PAM implementations are available: 66 67Solaris PAM: http://www.sun.com/software/solaris/pam/ 68Linux PAM: http://www.kernel.org/pub/linux/libs/pam/ 69OpenPAM: http://www.openpam.org/ 70 71If you wish to build the GNOME passphrase requester, you will need the GNOME 72libraries and headers. 73 74GNOME: 75http://www.gnome.org/ 76 77Alternatively, Jim Knoble <jmknoble@pobox.com> has written an excellent X11 78passphrase requester. This is maintained separately at: 79 80http://www.jmknoble.net/software/x11-ssh-askpass/ 81 82LibEdit: 83 84sftp supports command-line editing via NetBSD's libedit. If your platform 85has it available natively you can use that, alternatively you might try 86these multi-platform ports: 87 88http://www.thrysoee.dk/editline/ 89http://sourceforge.net/projects/libedit/ 90 91LDNS: 92 93LDNS is a DNS BSD-licensed resolver library which supports DNSSEC. 94 95http://nlnetlabs.nl/projects/ldns/ 96 97Autoconf: 98 99If you modify configure.ac or configure doesn't exist (eg if you checked 100the code out of git yourself) then you will need autoconf-2.69 to rebuild 101the automatically generated files by running "autoreconf". Earlier 102versions may also work but this is not guaranteed. 103 104http://www.gnu.org/software/autoconf/ 105 106Basic Security Module (BSM): 107 108Native BSM support is known to exist in Solaris from at least 2.5.1, 109FreeBSD 6.1 and OS X. Alternatively, you may use the OpenBSM 110implementation (http://www.openbsm.org). 111 112makedepend: 113 114https://www.x.org/archive/individual/util/ 115 116If you are making significant changes to the code you may need to rebuild 117the dependency (.depend) file using "make depend", which requires the 118"makedepend" tool from the X11 distribution. 119 120libfido2: 121 122libfido2 allows the use of hardware security keys over USB. libfido2 123in turn depends on libcbor. 124 125https://github.com/Yubico/libfido2 126https://github.com/pjk/libcbor 127 128 1292. Building / Installation 130-------------------------- 131 132To install OpenSSH with default options: 133 134./configure 135make 136make install 137 138This will install the OpenSSH binaries in /usr/local/bin, configuration files 139in /usr/local/etc, the server in /usr/local/sbin, etc. To specify a different 140installation prefix, use the --prefix option to configure: 141 142./configure --prefix=/opt 143make 144make install 145 146Will install OpenSSH in /opt/{bin,etc,lib,sbin}. You can also override 147specific paths, for example: 148 149./configure --prefix=/opt --sysconfdir=/etc/ssh 150make 151make install 152 153This will install the binaries in /opt/{bin,lib,sbin}, but will place the 154configuration files in /etc/ssh. 155 156If you are using PAM, you may need to manually install a PAM control 157file as "/etc/pam.d/sshd" (or wherever your system prefers to keep 158them). Note that the service name used to start PAM is __progname, 159which is the basename of the path of your sshd (e.g., the service name 160for /usr/sbin/osshd will be osshd). If you have renamed your sshd 161executable, your PAM configuration may need to be modified. 162 163A generic PAM configuration is included as "contrib/sshd.pam.generic", 164you may need to edit it before using it on your system. If you are 165using a recent version of Red Hat Linux, the config file in 166contrib/redhat/sshd.pam should be more useful. Failure to install a 167valid PAM file may result in an inability to use password 168authentication. On HP-UX 11 and Solaris, the standard /etc/pam.conf 169configuration will work with sshd (sshd will match the other service 170name). 171 172There are a few other options to the configure script: 173 174--with-audit=[module] enable additional auditing via the specified module. 175Currently, drivers for "debug" (additional info via syslog) and "bsm" 176(Sun's Basic Security Module) are supported. 177 178--with-pam enables PAM support. If PAM support is compiled in, it must 179also be enabled in sshd_config (refer to the UsePAM directive). 180 181--with-prngd-socket=/some/file allows you to enable EGD or PRNGD 182support and to specify a PRNGd socket. Use this if your Unix lacks 183/dev/random. 184 185--with-prngd-port=portnum allows you to enable EGD or PRNGD support 186and to specify a EGD localhost TCP port. Use this if your Unix lacks 187/dev/random. 188 189--with-lastlog=FILE will specify the location of the lastlog file. 190./configure searches a few locations for lastlog, but may not find 191it if lastlog is installed in a different place. 192 193--without-lastlog will disable lastlog support entirely. 194 195--with-osfsia, --without-osfsia will enable or disable OSF1's Security 196Integration Architecture. The default for OSF1 machines is enable. 197 198--with-md5-passwords will enable the use of MD5 passwords. Enable this 199if your operating system uses MD5 passwords and the system crypt() does 200not support them directly (see the crypt(3/3c) man page). If enabled, the 201resulting binary will support both MD5 and traditional crypt passwords. 202 203--with-utmpx enables utmpx support. utmpx support is automatic for 204some platforms. 205 206--without-shadow disables shadow password support. 207 208--with-ipaddr-display forces the use of a numeric IP address in the 209$DISPLAY environment variable. Some broken systems need this. 210 211--with-default-path=PATH allows you to specify a default $PATH for sessions 212started by sshd. This replaces the standard path entirely. 213 214--with-pid-dir=PATH specifies the directory in which the sshd.pid file is 215created. 216 217--with-xauth=PATH specifies the location of the xauth binary 218 219--with-ssl-dir=DIR allows you to specify where your Libre/OpenSSL 220libraries are installed. 221 222--with-ssl-engine enables Libre/OpenSSL's (hardware) ENGINE support 223 224--with-4in6 Check for IPv4 in IPv6 mapped addresses and convert them to 225real (AF_INET) IPv4 addresses. Works around some quirks on Linux. 226 227If you need to pass special options to the compiler or linker, you 228can specify these as environment variables before running ./configure. 229For example: 230 231CC="/usr/foo/cc" CFLAGS="-O" LDFLAGS="-s" LIBS="-lrubbish" ./configure 232 2333. Configuration 234---------------- 235 236The runtime configuration files are installed by in ${prefix}/etc or 237whatever you specified as your --sysconfdir (/usr/local/etc by default). 238 239The default configuration should be instantly usable, though you should 240review it to ensure that it matches your security requirements. 241 242To generate a host key, run "make host-key". Alternately you can do so 243manually using the following commands: 244 245 ssh-keygen -t [type] -f /etc/ssh/ssh_host_key -N "" 246 247for each of the types you wish to generate (rsa, dsa or ecdsa) or 248 249 ssh-keygen -A 250 251to generate keys for all supported types. 252 253Replacing /etc/ssh with the correct path to the configuration directory. 254(${prefix}/etc or whatever you specified with --sysconfdir during 255configuration). 256 257If you have configured OpenSSH with EGD support, ensure that EGD is 258running and has collected some Entropy. 259 260For more information on configuration, please refer to the manual pages 261for sshd, ssh and ssh-agent. 262 2634. (Optional) Send survey 264------------------------- 265 266$ make survey 267[check the contents of the file "survey" to ensure there's no information 268that you consider sensitive] 269$ make send-survey 270 271This will send configuration information for the currently configured 272host to a survey address. This will help determine which configurations 273are actually in use, and what valid combinations of configure options 274exist. The raw data is available only to the OpenSSH developers, however 275summary data may be published. 276 2775. Problems? 278------------ 279 280If you experience problems compiling, installing or running OpenSSH, 281please refer to the "reporting bugs" section of the webpage at 282https://www.openssh.com/ 283