mirror of
https://github.com/PowerShell/openssh-portable.git
synced 2025-07-28 16:24:39 +02:00
ce943912df
Have ssh-add accept a list of "destination constraints" that allow restricting where keys may be used in conjunction with a ssh-agent/ssh that supports session ID/hostkey binding. Constraints are specified as either "[user@]host-pattern" or "host-pattern>[user@]host-pattern". The first form permits a key to be used to authenticate as the specified user to the specified host. The second form permits a key that has previously been permitted for use at a host to be available via a forwarded agent to an additional host. For example, constraining a key with "user1@host_a" and "host_a>host_b". Would permit authentication as "user1" at "host_a", and allow the key to be available on an agent forwarded to "host_a" only for authentication to "host_b". The key would not be visible on agent forwarded to other hosts or usable for authentication there. Internally, destination constraints use host keys to identify hosts. The host patterns are used to obtain lists of host keys for that destination that are communicated to the agent. The user/hostkeys are encoded using a new restrict-destination-v00@openssh.com key constraint. host keys are looked up in the default client user/system known_hosts files. It is possible to override this set on the command-line. feedback Jann Horn & markus@ ok markus@ OpenBSD-Commit-ID: 6b52cd2b637f3d29ef543f0ce532a2bce6d86af5
Portable OpenSSH
OpenSSH is a complete implementation of the SSH protocol (version 2) for secure remote login, command execution and file transfer. It includes a client ssh and server sshd, file transfer utilities scp and sftp as well as tools for key generation (ssh-keygen), run-time key storage (ssh-agent) and a number of supporting programs.
This is a port of OpenBSD's OpenSSH to most Unix-like operating systems, including Linux, OS X and Cygwin. Portable OpenSSH polyfills OpenBSD APIs that are not available elsewhere, adds sshd sandboxing for more operating systems and includes support for OS-native authentication and auditing (e.g. using PAM).
Documentation
The official documentation for OpenSSH are the man pages for each tool:
Stable Releases
Stable release tarballs are available from a number of download mirrors. We recommend the use of a stable release for most users. Please read the release notes for details of recent changes and potential incompatibilities.
Building Portable OpenSSH
Dependencies
Portable OpenSSH is built using autoconf and make. It requires a working C compiler, standard library and headers.
libcrypto from either LibreSSL or OpenSSL may also be used, but OpenSSH may be built without it supporting a subset of crypto algorithms.
zlib is optional; without it transport compression is not supported.
FIDO security token support needs libfido2 and its dependencies. Also, certain platforms and build-time options may require additional dependencies; see README.platform for details.
Building a release
Releases include a pre-built copy of the configure script and may be built using:
tar zxvf openssh-X.YpZ.tar.gz
cd openssh
./configure # [options]
make && make tests
See the Build-time Customisation section below for configure options. If you plan on installing OpenSSH to your system, then you will usually want to specify destination paths.
Building from git
If building from git, you'll need autoconf installed to build the configure script. The following commands will check out and build portable OpenSSH from git:
git clone https://github.com/openssh/openssh-portable # or https://anongit.mindrot.org/openssh.git
cd openssh-portable
autoreconf
./configure
make && make tests
Build-time Customisation
There are many build-time customisation options available. All Autoconf destination path flags (e.g. --prefix) are supported (and are usually required if you want to install OpenSSH).
For a full list of available flags, run configure --help but a few of the more frequently-used ones are described below. Some of these flags will require additional libraries and/or headers be installed.
| Flag | Meaning |
|---|---|
--with-pam |
Enable PAM support. OpenPAM, Linux PAM and Solaris PAM are supported. |
--with-libedit |
Enable libedit support for sftp. |
--with-kerberos5 |
Enable Kerberos/GSSAPI support. Both Heimdal and MIT Kerberos implementations are supported. |
--with-selinux |
Enable SELinux support. |
--with-security-key-builtin |
Include built-in support for U2F/FIDO2 security keys. This requires libfido2 be installed. |
Development
Portable OpenSSH development is discussed on the openssh-unix-dev mailing list (archive mirror). Bugs and feature requests are tracked on our Bugzilla.
Reporting bugs
Non-security bugs may be reported to the developers via Bugzilla or via the mailing list above. Security bugs should be reported to openssh@openssh.com.