4d3fc8b057
This release fixes a number of security bugs and has minor new features and bug fixes. Security fixes, from the release notes (https://www.openssh.com/txt/release-9.3): This release contains fixes for a security problem and a memory safety problem. The memory safety problem is not believed to be exploitable, but we report most network-reachable memory faults as security bugs. * ssh-add(1): when adding smartcard keys to ssh-agent(1) with the per-hop destination constraints (ssh-add -h ...) added in OpenSSH 8.9, a logic error prevented the constraints from being communicated to the agent. This resulted in the keys being added without constraints. The common cases of non-smartcard keys and keys without destination constraints are unaffected. This problem was reported by Luci Stanescu. * ssh(1): Portable OpenSSH provides an implementation of the getrrsetbyname(3) function if the standard library does not provide it, for use by the VerifyHostKeyDNS feature. A specifically crafted DNS response could cause this function to perform an out-of-bounds read of adjacent stack data, but this condition does not appear to be exploitable beyond denial-of- service to the ssh(1) client. The getrrsetbyname(3) replacement is only included if the system's standard library lacks this function and portable OpenSSH was not compiled with the ldns library (--with-ldns). getrrsetbyname(3) is only invoked if using VerifyHostKeyDNS to fetch SSHFP records. This problem was found by the Coverity static analyzer. Sponsored by: The FreeBSD Foundation
5.1 KiB
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. OpenSSH may be built without either of these, but the resulting binaries will have only a subset of the cryptographic algorithms normally available.
zlib is optional; without it transport compression is not supported.
FIDO security token support needs libfido2 and its dependencies and will be enabled automatically if they are found.
In addition, certain platforms and build-time options may require additional dependencies; see README.platform for details about your platform.
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. |
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.