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Clean up OpenSSH HTML.

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<h2 id=OpenBSD>
<a href="/">
<i>Open</i><b>SSH</b></a>
Manual Pages
</h2>
<hr>

<p>
Web manual pages are available from OpenBSD for the following commands.
These manual pages reflect the latest development release of OpenSSH.

<ul>
<li><a href="https://man.openbsd.org/ssh">ssh(1)</a>
     &mdash; The basic rlogin/rsh-like client program
<li><a href="https://man.openbsd.org/sshd">sshd(8)</a>
     &mdash; The daemon that permits you to log in
<li><a href="https://man.openbsd.org/ssh_config">ssh_config(5)</a>
     &mdash; The client configuration file
<li><a href="https://man.openbsd.org/sshd_config">sshd_config(5)</a>
     &mdash; The daemon configuration file
<li><a href="https://man.openbsd.org/ssh-agent">ssh-agent(1)</a>
     &mdash; An authentication agent that can store private keys
<li><a href="https://man.openbsd.org/ssh-add">ssh-add(1)</a>
     &mdash; Tool which adds keys to in the above agent
<li><a href="https://man.openbsd.org/sftp">sftp(1)</a>
     &mdash; FTP-like program that works over SSH1 and SSH2 protocol
<li><a href="https://man.openbsd.org/scp">scp(1)</a>
     &mdash; File copy program that acts like rcp
<li><a href="https://man.openbsd.org/ssh-keygen">ssh-keygen(1)</a>
     &mdash; Key generation tool
<li><a href="https://man.openbsd.org/sftp-server">sftp-server(8)</a>
     &mdash; SFTP server subsystem (started automatically by sshd)
<li><a href="https://man.openbsd.org/ssh-keyscan">ssh-keyscan(1)</a>
     &mdash; Utility for gathering public host keys from a number of hosts
<li><a href="https://man.openbsd.org/ssh-keysign">ssh-keysign(8)</a>
     &mdash; Helper program for host-based authentication
</ul>

<p>
The SSH2 protocol implemented in OpenSSH is
standardized by the IETF
<a href="https://www.ietf.org/html.charters/secsh-charter.html">secsh</a>
working group and is specified in several RFCs and drafts.
The overall structure of SSH2 is described in the
<a href="https://www.ietf.org/rfc/rfc4251.txt">architecture</a> RFC.
It is composed of three layered components:

<ul>
<li>
The
<a href="https://www.ietf.org/rfc/rfc4253.txt">transport layer</a>
provides algorithm negotiation and a key exchange.
The key exchange includes server authentication and
results in a cryptographically secured connection:
it provides integrity, confidentiality and optional compression.

<li>
The
<a href="https://www.ietf.org/rfc/rfc4252.txt">user authentication layer</a>
uses the established connection and relies on the services provided
by the transport layer.
It provides several mechanisms for user authentication.
These include traditional password authentication as well as public-key
or host-based authentication mechanisms.

<li> The
<a href="https://www.ietf.org/rfc/rfc4254.txt">connection layer</a>
multiplexes many different concurrent channels over the authenticated connection
and allows tunneling of login sessions and TCP-forwarding.
It provides a flow control service for these channels.
Additionally, various channel-specific options can be negotiated.
</ul>

<p>
Additional documents specify:

<ul>
<li> The
<a href="https://www.ietf.org/rfc/rfc4256.txt">interactive
authentication</a>
RFC provides support for new authentication schemes like S/Key
or TIS authentication.

<li> The SFTP file transfer protocol is specified in the
<a href="txt/draft-ietf-secsh-filexfer-02.txt">filexfer</a> draft.
OpenSSH implements a SFTP
<a href="https://man.openbsd.org/sftp">client</a> and
<a href="https://man.openbsd.org/sftp-server">server</a>.

<li> A file format for public keys is specified in the
<a href="txt/draft-ietf-secsh-publickeyfile-02.txt">publickeyfile</a> draft.
The command
<a href="https://man.openbsd.org/ssh-keygen">ssh-keygen(1)</a> can be used
to convert an OpenSSH public key to this file format.

<li> The
<a href="https://www.ietf.org/rfc/rfc4419.txt">Diffie-Hellman Group Exchange</a> allows clients to request more secure groups for the Diffie-Hellman key exchange.

<li>OpenSSH implemented a compression method "zlib@openssh.com" that delays
    starting compression until after user authentication, to eliminate the
    risk of pre-authentication attacks against the compression code. It is
    described in
    <a href="txt/draft-miller-secsh-compression-delayed-00.txt">draft-miller-secsh-compression-delayed-00.txt</a>.

<li>OpenSSH implements an additional MAC (Message Authentication Code)
    "umac-64@openssh.com", which has superior performance to the ones specified
    in RFC 4253. It is described in
    <a href="txt/draft-miller-secsh-umac-01.txt">draft-miller-secsh-umac-01.txt</a>.

<li>The authentication agent protocol used by
    <a href="https://man.openbsd.org/ssh-agent">ssh-agent</a> is documented in the
    <a href="https://cvsweb.openbsd.org/src/usr.bin/ssh/PROTOCOL.agent?rev=HEAD">PROTOCOL.agent</a> file.

<li>OpenSSH makes various other minor extensions to and divergences from the
    standard SSH protocols. These are documented in the
    <a href="https://cvsweb.openbsd.org/src/usr.bin/ssh/PROTOCOL?rev=HEAD">PROTOCOL</a> file.
</ul>