.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
-.\" $OpenBSD: ssh_config.5,v 1.153 2011/08/02 01:22:11 djm Exp $
-.Dd $Mdocdate: August 2 2011 $
+.\" $OpenBSD: ssh_config.5,v 1.242 2017/02/27 14:30:33 jmc Exp $
+.Dd $Mdocdate: February 27 2017 $
.Dt SSH_CONFIG 5
.Os
.Sh NAME
For each parameter, the first obtained value
will be used.
The configuration files contain sections separated by
-.Dq Host
+.Cm Host
specifications, and that section is only applied for hosts that
match one of the patterns given in the specification.
-The matched host name is the one given on the command line.
+The matched host name is usually the one given on the command line
+(see the
+.Cm CanonicalizeHostname
+option for exceptions).
.Pp
Since the first obtained value for each parameter is used, more
host-specific declarations should be given near the beginning of the
file, and general defaults at the end.
.Pp
-The configuration file has the following format:
-.Pp
-Empty lines and lines starting with
+The file contains keyword-argument pairs, one per line.
+Lines starting with
.Ql #
-are comments.
-Otherwise a line is of the format
-.Dq keyword arguments .
+and empty lines are interpreted as comments.
+Arguments may optionally be enclosed in double quotes
+.Pq \&"
+in order to represent arguments containing spaces.
Configuration options may be separated by whitespace or
optional whitespace and exactly one
.Ql = ;
.Nm sftp
.Fl o
option.
-Arguments may optionally be enclosed in double quotes
-.Pq \&"
-in order to represent arguments containing spaces.
.Pp
The possible
keywords and their meanings are as follows (note that
.It Cm Host
Restricts the following declarations (up to the next
.Cm Host
+or
+.Cm Match
keyword) to be only for those hosts that match one of the patterns
given after the keyword.
If more than one pattern is provided, they should be separated by whitespace.
.Ql *
as a pattern can be used to provide global
defaults for all hosts.
-The host is the
+The host is usually the
.Ar hostname
-argument given on the command line (i.e. the name is not converted to
-a canonicalized host name before matching).
+argument given on the command line
+(see the
+.Cm CanonicalizeHostname
+keyword for exceptions).
.Pp
A pattern entry may be negated by prefixing it with an exclamation mark
.Pq Sq !\& .
See
.Sx PATTERNS
for more information on patterns.
+.It Cm Match
+Restricts the following declarations (up to the next
+.Cm Host
+or
+.Cm Match
+keyword) to be used only when the conditions following the
+.Cm Match
+keyword are satisfied.
+Match conditions are specified using one or more criteria
+or the single token
+.Cm all
+which always matches.
+The available criteria keywords are:
+.Cm canonical ,
+.Cm exec ,
+.Cm host ,
+.Cm originalhost ,
+.Cm user ,
+and
+.Cm localuser .
+The
+.Cm all
+criteria must appear alone or immediately after
+.Cm canonical .
+Other criteria may be combined arbitrarily.
+All criteria but
+.Cm all
+and
+.Cm canonical
+require an argument.
+Criteria may be negated by prepending an exclamation mark
+.Pq Sq !\& .
+.Pp
+The
+.Cm canonical
+keyword matches only when the configuration file is being re-parsed
+after hostname canonicalization (see the
+.Cm CanonicalizeHostname
+option.)
+This may be useful to specify conditions that work with canonical host
+names only.
+The
+.Cm exec
+keyword executes the specified command under the user's shell.
+If the command returns a zero exit status then the condition is considered true.
+Commands containing whitespace characters must be quoted.
+Arguments to
+.Cm exec
+accept the tokens described in the
+.Sx TOKENS
+section.
+.Pp
+The other keywords' criteria must be single entries or comma-separated
+lists and may use the wildcard and negation operators described in the
+.Sx PATTERNS
+section.
+The criteria for the
+.Cm host
+keyword are matched against the target hostname, after any substitution
+by the
+.Cm Hostname
+or
+.Cm CanonicalizeHostname
+options.
+The
+.Cm originalhost
+keyword matches against the hostname as it was specified on the command-line.
+The
+.Cm user
+keyword matches against the target username on the remote host.
+The
+.Cm localuser
+keyword matches against the name of the local user running
+.Xr ssh 1
+(this keyword may be useful in system-wide
+.Nm
+files).
+.It Cm AddKeysToAgent
+Specifies whether keys should be automatically added to a running
+.Xr ssh-agent 1 .
+If this option is set to
+.Cm yes
+and a key is loaded from a file, the key and its passphrase are added to
+the agent with the default lifetime, as if by
+.Xr ssh-add 1 .
+If this option is set to
+.Cm ask ,
+.Xr ssh 1
+will require confirmation using the
+.Ev SSH_ASKPASS
+program before adding a key (see
+.Xr ssh-add 1
+for details).
+If this option is set to
+.Cm confirm ,
+each use of the key must be confirmed, as if the
+.Fl c
+option was specified to
+.Xr ssh-add 1 .
+If this option is set to
+.Cm no ,
+no keys are added to the agent.
+The argument must be
+.Cm yes ,
+.Cm confirm ,
+.Cm ask ,
+or
+.Cm no
+(the default).
.It Cm AddressFamily
Specifies which address family to use when connecting.
Valid arguments are
-.Dq any ,
-.Dq inet
+.Cm any
+(the default),
+.Cm inet
(use IPv4 only), or
-.Dq inet6
+.Cm inet6
(use IPv6 only).
.It Cm BatchMode
If set to
-.Dq yes ,
+.Cm yes ,
passphrase/password querying will be disabled.
This option is useful in scripts and other batch jobs where no user
is present to supply the password.
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
.It Cm BindAddress
Use the specified address on the local machine as the source address of
the connection.
Note that this option does not work if
.Cm UsePrivilegedPort
is set to
-.Dq yes .
+.Cm yes .
+.It Cm CanonicalDomains
+When
+.Cm CanonicalizeHostname
+is enabled, this option specifies the list of domain suffixes in which to
+search for the specified destination host.
+.It Cm CanonicalizeFallbackLocal
+Specifies whether to fail with an error when hostname canonicalization fails.
+The default,
+.Cm yes ,
+will attempt to look up the unqualified hostname using the system resolver's
+search rules.
+A value of
+.Cm no
+will cause
+.Xr ssh 1
+to fail instantly if
+.Cm CanonicalizeHostname
+is enabled and the target hostname cannot be found in any of the domains
+specified by
+.Cm CanonicalDomains .
+.It Cm CanonicalizeHostname
+Controls whether explicit hostname canonicalization is performed.
+The default,
+.Cm no ,
+is not to perform any name rewriting and let the system resolver handle all
+hostname lookups.
+If set to
+.Cm yes
+then, for connections that do not use a
+.Cm ProxyCommand ,
+.Xr ssh 1
+will attempt to canonicalize the hostname specified on the command line
+using the
+.Cm CanonicalDomains
+suffixes and
+.Cm CanonicalizePermittedCNAMEs
+rules.
+If
+.Cm CanonicalizeHostname
+is set to
+.Cm always ,
+then canonicalization is applied to proxied connections too.
+.Pp
+If this option is enabled, then the configuration files are processed
+again using the new target name to pick up any new configuration in matching
+.Cm Host
+and
+.Cm Match
+stanzas.
+.It Cm CanonicalizeMaxDots
+Specifies the maximum number of dot characters in a hostname before
+canonicalization is disabled.
+The default, 1,
+allows a single dot (i.e. hostname.subdomain).
+.It Cm CanonicalizePermittedCNAMEs
+Specifies rules to determine whether CNAMEs should be followed when
+canonicalizing hostnames.
+The rules consist of one or more arguments of
+.Ar source_domain_list : Ns Ar target_domain_list ,
+where
+.Ar source_domain_list
+is a pattern-list of domains that may follow CNAMEs in canonicalization,
+and
+.Ar target_domain_list
+is a pattern-list of domains that they may resolve to.
+.Pp
+For example,
+.Qq *.a.example.com:*.b.example.com,*.c.example.com
+will allow hostnames matching
+.Qq *.a.example.com
+to be canonicalized to names in the
+.Qq *.b.example.com
+or
+.Qq *.c.example.com
+domains.
+.It Cm CertificateFile
+Specifies a file from which the user's certificate is read.
+A corresponding private key must be provided separately in order
+to use this certificate either
+from an
+.Cm IdentityFile
+directive or
+.Fl i
+flag to
+.Xr ssh 1 ,
+via
+.Xr ssh-agent 1 ,
+or via a
+.Cm PKCS11Provider .
+.Pp
+Arguments to
+.Cm CertificateFile
+may use the tilde syntax to refer to a user's home directory
+or the tokens described in the
+.Sx TOKENS
+section.
+.Pp
+It is possible to have multiple certificate files specified in
+configuration files; these certificates will be tried in sequence.
+Multiple
+.Cm CertificateFile
+directives will add to the list of certificates used for
+authentication.
.It Cm ChallengeResponseAuthentication
Specifies whether to use challenge-response authentication.
The argument to this keyword must be
-.Dq yes
+.Cm yes
+(the default)
or
-.Dq no .
-The default is
-.Dq yes .
+.Cm no .
.It Cm CheckHostIP
-If this flag is set to
-.Dq yes ,
+If set to
+.Cm yes
+(the default),
.Xr ssh 1
will additionally check the host IP address in the
.Pa known_hosts
file.
-This allows ssh to detect if a host key changed due to DNS spoofing.
+This allows it to detect if a host key changed due to DNS spoofing
+and will add addresses of destination hosts to
+.Pa ~/.ssh/known_hosts
+in the process, regardless of the setting of
+.Cm StrictHostKeyChecking .
If the option is set to
-.Dq no ,
+.Cm no ,
the check will not be executed.
-The default is
-.Dq yes .
.It Cm Cipher
Specifies the cipher to use for encrypting the session
in protocol version 1.
Currently,
-.Dq blowfish ,
-.Dq 3des ,
+.Cm blowfish ,
+.Cm 3des
+(the default),
and
-.Dq des
-are supported.
-.Ar des
+.Cm des
+are supported,
+though
+.Cm des
is only supported in the
.Xr ssh 1
-client for interoperability with legacy protocol 1 implementations
-that do not support the
-.Ar 3des
-cipher.
-Its use is strongly discouraged due to cryptographic weaknesses.
-The default is
-.Dq 3des .
+client for interoperability with legacy protocol 1 implementations;
+its use is strongly discouraged due to cryptographic weaknesses.
.It Cm Ciphers
Specifies the ciphers allowed for protocol version 2
in order of preference.
Multiple ciphers must be comma-separated.
-The supported ciphers are
-.Dq 3des-cbc ,
-.Dq aes128-cbc ,
-.Dq aes192-cbc ,
-.Dq aes256-cbc ,
-.Dq aes128-ctr ,
-.Dq aes192-ctr ,
-.Dq aes256-ctr ,
-.Dq arcfour128 ,
-.Dq arcfour256 ,
-.Dq arcfour ,
-.Dq blowfish-cbc ,
-and
-.Dq cast128-cbc .
+If the specified value begins with a
+.Sq +
+character, then the specified ciphers will be appended to the default set
+instead of replacing them.
+If the specified value begins with a
+.Sq -
+character, then the specified ciphers (including wildcards) will be removed
+from the default set instead of replacing them.
+.Pp
+The supported ciphers are:
+.Bd -literal -offset indent
+3des-cbc
+aes128-cbc
+aes192-cbc
+aes256-cbc
+aes128-ctr
+aes192-ctr
+aes256-ctr
+aes128-gcm@openssh.com
+aes256-gcm@openssh.com
+arcfour
+arcfour128
+arcfour256
+blowfish-cbc
+cast128-cbc
+chacha20-poly1305@openssh.com
+.Ed
+.Pp
The default is:
-.Bd -literal -offset 3n
-aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
-aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
-aes256-cbc,arcfour
+.Bd -literal -offset indent
+chacha20-poly1305@openssh.com,
+aes128-ctr,aes192-ctr,aes256-ctr,
+aes128-gcm@openssh.com,aes256-gcm@openssh.com,
+aes128-cbc,aes192-cbc,aes256-cbc
.Ed
+.Pp
+The list of available ciphers may also be obtained using
+.Qq ssh -Q cipher .
.It Cm ClearAllForwardings
Specifies that all local, remote, and dynamic port forwardings
specified in the configuration files or on the command line be
and
.Xr sftp 1 .
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
.It Cm Compression
Specifies whether to use compression.
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
.It Cm CompressionLevel
Specifies the compression level to use if compression is enabled.
The argument must be an integer from 1 (fast) to 9 (slow, best).
.It Cm ControlMaster
Enables the sharing of multiple sessions over a single network connection.
When set to
-.Dq yes ,
+.Cm yes ,
.Xr ssh 1
will listen for connections on a control socket specified using the
.Cm ControlPath
with
.Cm ControlMaster
set to
-.Dq no
+.Cm no
(the default).
These sessions will try to reuse the master instance's network connection
rather than initiating new ones, but will fall back to connecting normally
if the control socket does not exist, or is not listening.
.Pp
Setting this to
-.Dq ask
-will cause ssh
-to listen for control connections, but require confirmation using the
-.Ev SSH_ASKPASS
-program before they are accepted (see
-.Xr ssh-add 1
-for details).
+.Cm ask
+will cause
+.Xr ssh 1
+to listen for control connections, but require confirmation using
+.Xr ssh-askpass 1 .
If the
.Cm ControlPath
cannot be opened,
-ssh will continue without connecting to a master instance.
+.Xr ssh 1
+will continue without connecting to a master instance.
.Pp
X11 and
.Xr ssh-agent 1
master connection but fall back to creating a new one if one does not already
exist.
These options are:
-.Dq auto
+.Cm auto
and
-.Dq autoask .
+.Cm autoask .
The latter requires confirmation like the
-.Dq ask
+.Cm ask
option.
.It Cm ControlPath
Specify the path to the control socket used for connection sharing as described
in the
.Cm ControlMaster
section above or the string
-.Dq none
+.Cm none
to disable connection sharing.
-In the path,
-.Ql %L
-will be substituted by the first component of the local host name,
-.Ql %l
-will be substituted by the local host name (including any domain name),
-.Ql %h
-will be substituted by the target host name,
-.Ql %n
-will be substituted by the original target host name
-specified on the command line,
-.Ql %p
-the port,
-.Ql %r
-by the remote login username, and
-.Ql %u
-by the username of the user running
-.Xr ssh 1 .
+Arguments to
+.Cm ControlPath
+may use the tilde syntax to refer to a user's home directory
+or the tokens described in the
+.Sx TOKENS
+section.
It is recommended that any
.Cm ControlPath
used for opportunistic connection sharing include
-at least %h, %p, and %r.
+at least %h, %p, and %r (or alternatively %C) and be placed in a directory
+that is not writable by other users.
This ensures that shared connections are uniquely identified.
.It Cm ControlPersist
When used in conjunction with
in the background (waiting for future client connections)
after the initial client connection has been closed.
If set to
-.Dq no ,
+.Cm no ,
then the master connection will not be placed into the background,
and will close as soon as the initial client connection is closed.
If set to
-.Dq yes ,
+.Cm yes
+or 0,
then the master connection will remain in the background indefinitely
(until killed or closed via a mechanism such as the
-.Xr ssh 1
-.Dq Fl O No exit
-option).
+.Qq ssh -O exit ) .
If set to a time in seconds, or a time in any of the formats documented in
.Xr sshd_config 5 ,
then the backgrounded master connection will automatically terminate
The
.Ar bind_address
of
-.Dq localhost
+.Cm localhost
indicates that the listening port be bound for local use only, while an
empty address or
.Sq *
Only the superuser can forward privileged ports.
.It Cm EnableSSHKeysign
Setting this option to
-.Dq yes
+.Cm yes
in the global client configuration file
.Pa /etc/ssh/ssh_config
enables the use of the helper program
during
.Cm HostbasedAuthentication .
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
This option should be placed in the non-hostspecific section.
See
.Xr ssh-keysign 8
The argument should be a single character,
.Ql ^
followed by a letter, or
-.Dq none
+.Cm none
to disable the escape
character entirely (making the connection transparent for binary
data).
Specifies whether
.Xr ssh 1
should terminate the connection if it cannot set up all requested
-dynamic, tunnel, local, and remote port forwardings.
+dynamic, tunnel, local, and remote port forwardings, (e.g.\&
+if either end is unable to bind and listen on a specified port).
+Note that
+.Cm ExitOnForwardFailure
+does not apply to connections made over port forwardings and will not,
+for example, cause
+.Xr ssh 1
+to exit if TCP connections to the ultimate forwarding destination fail.
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
+.It Cm FingerprintHash
+Specifies the hash algorithm used when displaying key fingerprints.
+Valid options are:
+.Cm md5
+and
+.Cm sha256
+(the default).
.It Cm ForwardAgent
Specifies whether the connection to the authentication agent (if any)
will be forwarded to the remote machine.
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
.Pp
Agent forwarding should be enabled with caution.
Users with the ability to bypass file permissions on the remote host
.Ev DISPLAY
set.
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
.Pp
X11 forwarding should be enabled with caution.
Users with the ability to bypass file permissions on the remote host
elapsed.
.It Cm ForwardX11Trusted
If this option is set to
-.Dq yes ,
+.Cm yes ,
remote X11 clients will have full access to the original X11 display.
.Pp
If this option is set to
-.Dq no ,
+.Cm no
+(the default),
remote X11 clients will be considered untrusted and prevented
from stealing or tampering with data belonging to trusted X11
clients.
token used for the session will be set to expire after 20 minutes.
Remote clients will be refused access after this time.
.Pp
-The default is
-.Dq no .
-.Pp
See the X11 SECURITY extension specification for full details on
the restrictions imposed on untrusted clients.
.It Cm GatewayPorts
should bind local port forwardings to the wildcard address,
thus allowing remote hosts to connect to forwarded ports.
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
.It Cm GlobalKnownHostsFile
Specifies one or more files to use for the global
host key database, separated by whitespace.
.It Cm GSSAPIAuthentication
Specifies whether user authentication based on GSSAPI is allowed.
The default is
-.Dq no .
-Note that this option applies to protocol version 2 only.
+.Cm no .
.It Cm GSSAPIDelegateCredentials
Forward (delegate) credentials to the server.
The default is
-.Dq no .
-Note that this option applies to protocol version 2 only.
+.Cm no .
.It Cm HashKnownHosts
Indicates that
.Xr ssh 1
but they do not reveal identifying information should the file's contents
be disclosed.
The default is
-.Dq no .
+.Cm no .
Note that existing names and addresses in known hosts files
will not be converted automatically,
but may be manually hashed using
Specifies whether to try rhosts based authentication with public key
authentication.
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
-This option applies to protocol version 2 only and
-is similar to
-.Cm RhostsRSAAuthentication .
+.Cm no
+(the default).
+.It Cm HostbasedKeyTypes
+Specifies the key types that will be used for hostbased authentication
+as a comma-separated pattern list.
+Alternately if the specified value begins with a
+.Sq +
+character, then the specified key types will be appended to the default set
+instead of replacing them.
+If the specified value begins with a
+.Sq -
+character, then the specified key types (including wildcards) will be removed
+from the default set instead of replacing them.
+The default for this option is:
+.Bd -literal -offset 3n
+ecdsa-sha2-nistp256-cert-v01@openssh.com,
+ecdsa-sha2-nistp384-cert-v01@openssh.com,
+ecdsa-sha2-nistp521-cert-v01@openssh.com,
+ssh-ed25519-cert-v01@openssh.com,
+ssh-rsa-cert-v01@openssh.com,
+ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
+ssh-ed25519,ssh-rsa
+.Ed
+.Pp
+The
+.Fl Q
+option of
+.Xr ssh 1
+may be used to list supported key types.
.It Cm HostKeyAlgorithms
-Specifies the protocol version 2 host key algorithms
+Specifies the host key algorithms
that the client wants to use in order of preference.
+Alternately if the specified value begins with a
+.Sq +
+character, then the specified key types will be appended to the default set
+instead of replacing them.
+If the specified value begins with a
+.Sq -
+character, then the specified key types (including wildcards) will be removed
+from the default set instead of replacing them.
The default for this option is:
.Bd -literal -offset 3n
ecdsa-sha2-nistp256-cert-v01@openssh.com,
ecdsa-sha2-nistp384-cert-v01@openssh.com,
ecdsa-sha2-nistp521-cert-v01@openssh.com,
-ssh-rsa-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com,
-ssh-rsa-cert-v00@openssh.com,ssh-dss-cert-v00@openssh.com,
+ssh-ed25519-cert-v01@openssh.com,
+ssh-rsa-cert-v01@openssh.com,
ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
-ssh-rsa,ssh-dss
+ssh-ed25519,ssh-rsa
.Ed
.Pp
If hostkeys are known for the destination host then this default is modified
to prefer their algorithms.
+.Pp
+The list of available key types may also be obtained using
+.Qq ssh -Q key .
.It Cm HostKeyAlias
Specifies an alias that should be used instead of the
real host name when looking up or saving the host key
.It Cm HostName
Specifies the real host name to log into.
This can be used to specify nicknames or abbreviations for hosts.
-If the hostname contains the character sequence
-.Ql %h ,
-then this will be replaced with the host name specified on the command line
-(this is useful for manipulating unqualified names).
-The default is the name given on the command line.
+Arguments to
+.Cm HostName
+accept the tokens described in the
+.Sx TOKENS
+section.
Numeric IP addresses are also permitted (both on the command line and in
.Cm HostName
specifications).
+The default is the name given on the command line.
.It Cm IdentitiesOnly
Specifies that
.Xr ssh 1
-should only use the authentication identity files configured in the
+should only use the authentication identity and certificate files explicitly
+configured in the
.Nm
-files,
+files
+or passed on the
+.Xr ssh 1
+command-line,
even if
.Xr ssh-agent 1
+or a
+.Cm PKCS11Provider
offers more identities.
The argument to this keyword must be
-.Dq yes
+.Cm yes
or
-.Dq no .
+.Cm no
+(the default).
This option is intended for situations where ssh-agent
offers many different identities.
-The default is
-.Dq no .
+.It Cm IdentityAgent
+Specifies the
+.Ux Ns -domain
+socket used to communicate with the authentication agent.
+.Pp
+This option overrides the
+.Ev SSH_AUTH_SOCK
+environment variable and can be used to select a specific agent.
+Setting the socket name to
+.Cm none
+disables the use of an authentication agent.
+If the string
+.Qq SSH_AUTH_SOCK
+is specified, the location of the socket will be read from the
+.Ev SSH_AUTH_SOCK
+environment variable.
+.Pp
+Arguments to
+.Cm IdentityAgent
+may use the tilde syntax to refer to a user's home directory
+or the tokens described in the
+.Sx TOKENS
+section.
.It Cm IdentityFile
-Specifies a file from which the user's DSA, ECDSA or DSA authentication
+Specifies a file from which the user's DSA, ECDSA, Ed25519 or RSA authentication
identity is read.
The default is
.Pa ~/.ssh/identity
for protocol version 1, and
.Pa ~/.ssh/id_dsa ,
-.Pa ~/.ssh/id_ecdsa
+.Pa ~/.ssh/id_ecdsa ,
+.Pa ~/.ssh/id_ed25519
and
.Pa ~/.ssh/id_rsa
for protocol version 2.
Additionally, any identities represented by the authentication agent
-will be used for authentication.
+will be used for authentication unless
+.Cm IdentitiesOnly
+is set.
+If no certificates have been explicitly specified by
+.Cm CertificateFile ,
.Xr ssh 1
will try to load certificate information from the filename obtained by
appending
to the path of a specified
.Cm IdentityFile .
.Pp
-The file name may use the tilde
-syntax to refer to a user's home directory or one of the following
-escape characters:
-.Ql %d
-(local user's home directory),
-.Ql %u
-(local user name),
-.Ql %l
-(local host name),
-.Ql %h
-(remote host name) or
-.Ql %r
-(remote user name).
+Arguments to
+.Cm IdentityFile
+may use the tilde syntax to refer to a user's home directory
+or the tokens described in the
+.Sx TOKENS
+section.
.Pp
It is possible to have
multiple identity files specified in configuration files; all these
.Cm IdentityFile
directives will add to the list of identities tried (this behaviour
differs from that of other configuration directives).
+.Pp
+.Cm IdentityFile
+may be used in conjunction with
+.Cm IdentitiesOnly
+to select which identities in an agent are offered during authentication.
+.Cm IdentityFile
+may also be used in conjunction with
+.Cm CertificateFile
+in order to provide any certificate also needed for authentication with
+the identity.
+.It Cm IgnoreUnknown
+Specifies a pattern-list of unknown options to be ignored if they are
+encountered in configuration parsing.
+This may be used to suppress errors if
+.Nm
+contains options that are unrecognised by
+.Xr ssh 1 .
+It is recommended that
+.Cm IgnoreUnknown
+be listed early in the configuration file as it will not be applied
+to unknown options that appear before it.
+.It Cm Include
+Include the specified configuration file(s).
+Multiple pathnames may be specified and each pathname may contain
+.Xr glob 3
+wildcards and, for user configurations, shell-like
+.Sq ~
+references to user home directories.
+Files without absolute paths are assumed to be in
+.Pa ~/.ssh
+if included in a user configuration file or
+.Pa /etc/ssh
+if included from the system configuration file.
+.Cm Include
+directive may appear inside a
+.Cm Match
+or
+.Cm Host
+block
+to perform conditional inclusion.
.It Cm IPQoS
Specifies the IPv4 type-of-service or DSCP class for connections.
Accepted values are
-.Dq af11 ,
-.Dq af12 ,
-.Dq af13 ,
-.Dq af14 ,
-.Dq af22 ,
-.Dq af23 ,
-.Dq af31 ,
-.Dq af32 ,
-.Dq af33 ,
-.Dq af41 ,
-.Dq af42 ,
-.Dq af43 ,
-.Dq cs0 ,
-.Dq cs1 ,
-.Dq cs2 ,
-.Dq cs3 ,
-.Dq cs4 ,
-.Dq cs5 ,
-.Dq cs6 ,
-.Dq cs7 ,
-.Dq ef ,
-.Dq lowdelay ,
-.Dq throughput ,
-.Dq reliability ,
+.Cm af11 ,
+.Cm af12 ,
+.Cm af13 ,
+.Cm af21 ,
+.Cm af22 ,
+.Cm af23 ,
+.Cm af31 ,
+.Cm af32 ,
+.Cm af33 ,
+.Cm af41 ,
+.Cm af42 ,
+.Cm af43 ,
+.Cm cs0 ,
+.Cm cs1 ,
+.Cm cs2 ,
+.Cm cs3 ,
+.Cm cs4 ,
+.Cm cs5 ,
+.Cm cs6 ,
+.Cm cs7 ,
+.Cm ef ,
+.Cm lowdelay ,
+.Cm throughput ,
+.Cm reliability ,
or a numeric value.
This option may take one or two arguments, separated by whitespace.
If one argument is specified, it is used as the packet class unconditionally.
If two values are specified, the first is automatically selected for
interactive sessions and the second for non-interactive sessions.
The default is
-.Dq lowdelay
+.Cm lowdelay
for interactive sessions and
-.Dq throughput
+.Cm throughput
for non-interactive sessions.
.It Cm KbdInteractiveAuthentication
Specifies whether to use keyboard-interactive authentication.
The argument to this keyword must be
-.Dq yes
+.Cm yes
+(the default)
or
-.Dq no .
-The default is
-.Dq yes .
+.Cm no .
.It Cm KbdInteractiveDevices
Specifies the list of methods to use in keyboard-interactive authentication.
Multiple method names must be comma-separated.
The methods available vary depending on what the server supports.
For an OpenSSH server,
it may be zero or more of:
-.Dq bsdauth ,
-.Dq pam ,
+.Cm bsdauth ,
+.Cm pam ,
and
-.Dq skey .
+.Cm skey .
.It Cm KexAlgorithms
Specifies the available KEX (Key Exchange) algorithms.
Multiple algorithms must be comma-separated.
+Alternately if the specified value begins with a
+.Sq +
+character, then the specified methods will be appended to the default set
+instead of replacing them.
+If the specified value begins with a
+.Sq -
+character, then the specified methods (including wildcards) will be removed
+from the default set instead of replacing them.
The default is:
.Bd -literal -offset indent
+curve25519-sha256,curve25519-sha256@libssh.org,
ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,
diffie-hellman-group-exchange-sha256,
diffie-hellman-group-exchange-sha1,
-diffie-hellman-group14-sha1,
-diffie-hellman-group1-sha1
+diffie-hellman-group14-sha1
.Ed
+.Pp
+The list of available key exchange algorithms may also be obtained using
+.Qq ssh -Q kex .
.It Cm LocalCommand
Specifies a command to execute on the local machine after successfully
connecting to the server.
The command string extends to the end of the line, and is executed with
the user's shell.
-The following escape character substitutions will be performed:
-.Ql %d
-(local user's home directory),
-.Ql %h
-(remote host name),
-.Ql %l
-(local host name),
-.Ql %n
-(host name as provided on the command line),
-.Ql %p
-(remote port),
-.Ql %r
-(remote user name) or
-.Ql %u
-(local user name).
+Arguments to
+.Cm LocalCommand
+accept the tokens described in the
+.Sx TOKENS
+section.
.Pp
The command is run synchronously and does not have access to the
session of the
The
.Ar bind_address
of
-.Dq localhost
+.Cm localhost
indicates that the listening port be bound for local use only, while an
empty address or
.Sq *
.It Cm MACs
Specifies the MAC (message authentication code) algorithms
in order of preference.
-The MAC algorithm is used in protocol version 2
-for data integrity protection.
+The MAC algorithm is used for data integrity protection.
Multiple algorithms must be comma-separated.
+If the specified value begins with a
+.Sq +
+character, then the specified algorithms will be appended to the default set
+instead of replacing them.
+If the specified value begins with a
+.Sq -
+character, then the specified algorithms (including wildcards) will be removed
+from the default set instead of replacing them.
+.Pp
+The algorithms that contain
+.Qq -etm
+calculate the MAC after encryption (encrypt-then-mac).
+These are considered safer and their use recommended.
+.Pp
The default is:
.Bd -literal -offset indent
-hmac-md5,hmac-sha1,umac-64@openssh.com,
-hmac-ripemd160,hmac-sha1-96,hmac-md5-96,
-hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,
-hmac-sha2-512-96
+umac-64-etm@openssh.com,umac-128-etm@openssh.com,
+hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,
+hmac-sha1-etm@openssh.com,
+umac-64@openssh.com,umac-128@openssh.com,
+hmac-sha2-256,hmac-sha2-512,hmac-sha1
.Ed
+.Pp
+The list of available MAC algorithms may also be obtained using
+.Qq ssh -Q mac .
.It Cm NoHostAuthenticationForLocalhost
This option can be used if the home directory is shared across machines.
In this case localhost will refer to a different machine on each of
the machines and the user will get many warnings about changed host keys.
However, this option disables host authentication for localhost.
The argument to this keyword must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is to check the host key for localhost.
+.Cm no
+(the default).
.It Cm NumberOfPasswordPrompts
Specifies the number of password prompts before giving up.
The argument to this keyword must be an integer.
.It Cm PasswordAuthentication
Specifies whether to use password authentication.
The argument to this keyword must be
-.Dq yes
+.Cm yes
+(the default)
or
-.Dq no .
-The default is
-.Dq yes .
+.Cm no .
.It Cm PermitLocalCommand
Allow local command execution via the
.Ic LocalCommand
escape sequence in
.Xr ssh 1 .
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
.It Cm PKCS11Provider
Specifies which PKCS#11 provider to use.
The argument to this keyword is the PKCS#11 shared library
Specifies the port number to connect on the remote host.
The default is 22.
.It Cm PreferredAuthentications
-Specifies the order in which the client should try protocol 2
-authentication methods.
+Specifies the order in which the client should try authentication methods.
This allows a client to prefer one method (e.g.\&
.Cm keyboard-interactive )
over another method (e.g.\&
Specifies the protocol versions
.Xr ssh 1
should support in order of preference.
-The possible values are
-.Sq 1
-and
-.Sq 2 .
+The possible values are 1 and 2.
Multiple versions must be comma-separated.
When this option is set to
-.Dq 2,1
+.Cm 2,1
.Nm ssh
will try version 2 and fall back to version 1
if version 2 is not available.
-The default is
-.Sq 2 .
+The default is version 2.
+Protocol 1 suffers from a number of cryptographic weaknesses and should
+not be used.
+It is only offered to support legacy devices.
.It Cm ProxyCommand
Specifies the command to use to connect to the server.
The command
-string extends to the end of the line, and is executed with
-the user's shell.
-In the command string, any occurrence of
-.Ql %h
-will be substituted by the host name to
-connect,
-.Ql %p
-by the port, and
-.Ql %r
-by the remote user name.
+string extends to the end of the line, and is executed
+using the user's shell
+.Ql exec
+directive to avoid a lingering shell process.
+.Pp
+Arguments to
+.Cm ProxyCommand
+accept the tokens described in the
+.Sx TOKENS
+section.
The command can be basically anything,
and should read from its standard input and write to its standard output.
It should eventually connect an
HostName of the host being connected (defaulting to the name typed by
the user).
Setting the command to
-.Dq none
+.Cm none
disables this option entirely.
Note that
.Cm CheckHostIP
.Bd -literal -offset 3n
ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p
.Ed
+.It Cm ProxyJump
+Specifies one or more jump proxies as
+.Xo
+.Sm off
+.Op Ar user No @
+.Ar host
+.Op : Ns Ar port
+.Sm on
+.Xc .
+Multiple proxies may be separated by comma characters and will be visited
+sequentially.
+Setting this option will cause
+.Xr ssh 1
+to connect to the target host by first making a
+.Xr ssh 1
+connection to the specified
+.Cm ProxyJump
+host and then establishing a
+TCP forwarding to the ultimate target from there.
+.Pp
+Note that this option will compete with the
+.Cm ProxyCommand
+option - whichever is specified first will prevent later instances of the
+other from taking effect.
+.It Cm ProxyUseFdpass
+Specifies that
+.Cm ProxyCommand
+will pass a connected file descriptor back to
+.Xr ssh 1
+instead of continuing to execute and pass data.
+The default is
+.Cm no .
+.It Cm PubkeyAcceptedKeyTypes
+Specifies the key types that will be used for public key authentication
+as a comma-separated pattern list.
+Alternately if the specified value begins with a
+.Sq +
+character, then the key types after it will be appended to the default
+instead of replacing it.
+If the specified value begins with a
+.Sq -
+character, then the specified key types (including wildcards) will be removed
+from the default set instead of replacing them.
+The default for this option is:
+.Bd -literal -offset 3n
+ecdsa-sha2-nistp256-cert-v01@openssh.com,
+ecdsa-sha2-nistp384-cert-v01@openssh.com,
+ecdsa-sha2-nistp521-cert-v01@openssh.com,
+ssh-ed25519-cert-v01@openssh.com,
+ssh-rsa-cert-v01@openssh.com,
+ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
+ssh-ed25519,ssh-rsa
+.Ed
+.Pp
+The list of available key types may also be obtained using
+.Qq ssh -Q key .
.It Cm PubkeyAuthentication
Specifies whether to try public key authentication.
The argument to this keyword must be
-.Dq yes
+.Cm yes
+(the default)
or
-.Dq no .
-The default is
-.Dq yes .
-This option applies to protocol version 2 only.
+.Cm no .
.It Cm RekeyLimit
Specifies the maximum amount of data that may be transmitted before the
-session key is renegotiated.
-The argument is the number of bytes, with an optional suffix of
+session key is renegotiated, optionally followed a maximum amount of
+time that may pass before the session key is renegotiated.
+The first argument is specified in bytes and may have a suffix of
.Sq K ,
.Sq M ,
or
and
.Sq 4G ,
depending on the cipher.
-This option applies to protocol version 2 only.
+The optional second value is specified in seconds and may use any of the
+units documented in the
+.Sx TIME FORMATS
+section of
+.Xr sshd_config 5 .
+The default value for
+.Cm RekeyLimit
+is
+.Cm default none ,
+which means that rekeying is performed after the cipher's default amount
+of data has been sent or received and no time based rekeying is done.
.It Cm RemoteForward
Specifies that a TCP port on the remote machine be forwarded over
the secure channel to the specified host and port from the local machine.
.Pp
If the
.Ar port
-argument is
-.Ql 0 ,
+argument is 0,
the listen port will be dynamically allocated on the server and reported
to the client at run time.
.Pp
.It Cm RequestTTY
Specifies whether to request a pseudo-tty for the session.
The argument may be one of:
-.Dq no
+.Cm no
(never request a TTY),
-.Dq yes
+.Cm yes
(always request a TTY when standard input is a TTY),
-.Dq force
+.Cm force
(always request a TTY) or
-.Dq auto
+.Cm auto
(request a TTY when opening a login session).
This option mirrors the
.Fl t
.Fl T
flags for
.Xr ssh 1 .
+.It Cm RevokedHostKeys
+Specifies revoked host public keys.
+Keys listed in this file will be refused for host authentication.
+Note that if this file does not exist or is not readable,
+then host authentication will be refused for all hosts.
+Keys may be specified as a text file, listing one public key per line, or as
+an OpenSSH Key Revocation List (KRL) as generated by
+.Xr ssh-keygen 1 .
+For more information on KRLs, see the KEY REVOCATION LISTS section in
+.Xr ssh-keygen 1 .
.It Cm RhostsRSAAuthentication
Specifies whether to try rhosts based authentication with RSA host
authentication.
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
This option applies to protocol version 1 only and requires
.Xr ssh 1
to be setuid root.
.It Cm RSAAuthentication
Specifies whether to try RSA authentication.
The argument to this keyword must be
-.Dq yes
+.Cm yes
+(the default)
or
-.Dq no .
+.Cm no .
RSA authentication will only be
attempted if the identity file exists, or an authentication agent is
running.
-The default is
-.Dq yes .
Note that this option applies to protocol version 1 only.
.It Cm SendEnv
Specifies what variables from the local
.Xr environ 7
should be sent to the server.
-Note that environment passing is only supported for protocol 2.
The server must also support it, and the server must be configured to
accept these environment variables.
+Note that the
+.Ev TERM
+environment variable is always sent whenever a
+pseudo-terminal is requested as it is required by the protocol.
Refer to
.Cm AcceptEnv
in
.Cm ServerAliveCountMax
is left at the default, if the server becomes unresponsive,
ssh will disconnect after approximately 45 seconds.
-This option applies to protocol version 2 only.
.It Cm ServerAliveInterval
Sets a timeout interval in seconds after which if no data has been received
from the server,
channel to request a response from the server.
The default
is 0, indicating that these messages will not be sent to the server.
-This option applies to protocol version 2 only.
+.It Cm StreamLocalBindMask
+Sets the octal file creation mode mask
+.Pq umask
+used when creating a Unix-domain socket file for local or remote
+port forwarding.
+This option is only used for port forwarding to a Unix-domain socket file.
+.Pp
+The default value is 0177, which creates a Unix-domain socket file that is
+readable and writable only by the owner.
+Note that not all operating systems honor the file mode on Unix-domain
+socket files.
+.It Cm StreamLocalBindUnlink
+Specifies whether to remove an existing Unix-domain socket file for local
+or remote port forwarding before creating a new one.
+If the socket file already exists and
+.Cm StreamLocalBindUnlink
+is not enabled,
+.Nm ssh
+will be unable to forward the port to the Unix-domain socket file.
+This option is only used for port forwarding to a Unix-domain socket file.
+.Pp
+The argument must be
+.Cm yes
+or
+.Cm no
+(the default).
.It Cm StrictHostKeyChecking
If this flag is set to
-.Dq yes ,
+.Cm yes ,
.Xr ssh 1
will never automatically add host keys to the
.Pa ~/.ssh/known_hosts
This option forces the user to manually
add all new hosts.
If this flag is set to
-.Dq no ,
+.Cm no ,
ssh will automatically add new host keys to the
user known hosts files.
If this flag is set to
-.Dq ask ,
+.Cm ask
+(the default),
new host keys
will be added to the user known host files only after the user
has confirmed that is what they really want to do, and
ssh will refuse to connect to hosts whose host key has changed.
The host keys of
known hosts will be verified automatically in all cases.
-The argument must be
-.Dq yes ,
-.Dq no ,
-or
-.Dq ask .
-The default is
-.Dq ask .
.It Cm TCPKeepAlive
Specifies whether the system should send TCP keepalive messages to the
other side.
find it annoying.
.Pp
The default is
-.Dq yes
+.Cm yes
(to send TCP keepalive messages), and the client will notice
if the network goes down or the remote host dies.
This is important in scripts, and many users want it too.
.Pp
To disable TCP keepalive messages, the value should be set to
-.Dq no .
+.Cm no .
.It Cm Tunnel
Request
.Xr tun 4
device forwarding between the client and the server.
The argument must be
-.Dq yes ,
-.Dq point-to-point
+.Cm yes ,
+.Cm point-to-point
(layer 3),
-.Dq ethernet
+.Cm ethernet
(layer 2),
or
-.Dq no .
+.Cm no
+(the default).
Specifying
-.Dq yes
+.Cm yes
requests the default tunnel mode, which is
-.Dq point-to-point .
-The default is
-.Dq no .
+.Cm point-to-point .
.It Cm TunnelDevice
Specifies the
.Xr tun 4
.Ar local_tun Op : Ar remote_tun .
.Sm on
The devices may be specified by numerical ID or the keyword
-.Dq any ,
+.Cm any ,
which uses the next available tunnel device.
If
.Ar remote_tun
is not specified, it defaults to
-.Dq any .
+.Cm any .
The default is
-.Dq any:any .
+.Cm any:any .
+.It Cm UpdateHostKeys
+Specifies whether
+.Xr ssh 1
+should accept notifications of additional hostkeys from the server sent
+after authentication has completed and add them to
+.Cm UserKnownHostsFile .
+The argument must be
+.Cm yes ,
+.Cm no
+(the default) or
+.Cm ask .
+Enabling this option allows learning alternate hostkeys for a server
+and supports graceful key rotation by allowing a server to send replacement
+public keys before old ones are removed.
+Additional hostkeys are only accepted if the key used to authenticate the
+host was already trusted or explicitly accepted by the user.
+If
+.Cm UpdateHostKeys
+is set to
+.Cm ask ,
+then the user is asked to confirm the modifications to the known_hosts file.
+Confirmation is currently incompatible with
+.Cm ControlPersist ,
+and will be disabled if it is enabled.
+.Pp
+Presently, only
+.Xr sshd 8
+from OpenSSH 6.8 and greater support the
+.Qq hostkeys@openssh.com
+protocol extension used to inform the client of all the server's hostkeys.
.It Cm UsePrivilegedPort
Specifies whether to use a privileged port for outgoing connections.
The argument must be
-.Dq yes
+.Cm yes
or
-.Dq no .
-The default is
-.Dq no .
+.Cm no
+(the default).
If set to
-.Dq yes ,
+.Cm yes ,
.Xr ssh 1
must be setuid root.
Note that this option must be set to
-.Dq yes
+.Cm yes
for
.Cm RhostsRSAAuthentication
with older servers.
Specifies whether to verify the remote key using DNS and SSHFP resource
records.
If this option is set to
-.Dq yes ,
+.Cm yes ,
the client will implicitly trust keys that match a secure fingerprint
from DNS.
Insecure fingerprints will be handled as if this option was set to
-.Dq ask .
+.Cm ask .
If this option is set to
-.Dq ask ,
+.Cm ask ,
information on fingerprint match will be displayed, but the user will still
need to confirm new host keys according to the
.Cm StrictHostKeyChecking
option.
-The argument must be
-.Dq yes ,
-.Dq no ,
-or
-.Dq ask .
The default is
-.Dq no .
-Note that this option applies to protocol version 2 only.
+.Cm no .
.Pp
See also
.Sx VERIFYING HOST KEYS
.Xr ssh 1 .
.It Cm VisualHostKey
If this flag is set to
-.Dq yes ,
+.Cm yes ,
an ASCII art representation of the remote host key fingerprint is
-printed in addition to the hex fingerprint string at login and
+printed in addition to the fingerprint string at login and
for unknown host keys.
If this flag is set to
-.Dq no ,
+.Cm no
+(the default),
no fingerprint strings are printed at login and
-only the hex fingerprint string will be printed for unknown host keys.
-The default is
-.Dq no .
+only the fingerprint string will be printed for unknown host keys.
.It Cm XAuthLocation
Specifies the full pathname of the
.Xr xauth 1
.Sq ?\&
(a wildcard that matches exactly one character).
For example, to specify a set of declarations for any host in the
-.Dq .co.uk
+.Qq .co.uk
set of domains,
the following pattern could be used:
.Pp
by preceding them with an exclamation mark
.Pq Sq !\& .
For example,
-to allow a key to be used from anywhere within an organisation
+to allow a key to be used from anywhere within an organization
except from the
-.Dq dialup
+.Qq dialup
pool,
the following entry (in authorized_keys) could be used:
.Pp
.Dl from=\&"!*.dialup.example.com,*.example.com\&"
+.Sh TOKENS
+Arguments to some keywords can make use of tokens,
+which are expanded at runtime:
+.Pp
+.Bl -tag -width XXXX -offset indent -compact
+.It %%
+A literal
+.Sq % .
+.It \&%C
+Shorthand for %l%h%p%r.
+.It %d
+Local user's home directory.
+.It %h
+The remote hostname.
+.It %i
+The local user ID.
+.It %L
+The local hostname.
+.It %l
+The local hostname, including the domain name.
+.It %n
+The original remote hostname, as given on the command line.
+.It %p
+The remote port.
+.It %r
+The remote username.
+.It %u
+The local username.
+.El
+.Pp
+.Cm Match exec
+accepts the tokens %%, %h, %L, %l, %n, %p, %r, and %u.
+.Pp
+.Cm CertificateFile
+accepts the tokens %%, %d, %h, %l, %r, and %u.
+.Pp
+.Cm ControlPath
+accepts the tokens %%, %C, %h, %i, %L, %l, %n, %p, %r, and %u.
+.Pp
+.Cm HostName
+accepts the tokens %% and %h.
+.Pp
+.Cm IdentityAgent
+and
+.Cm IdentityFile
+accept the tokens %%, %d, %h, %l, %r, and %u.
+.Pp
+.Cm LocalCommand
+accepts the tokens %%, %C, %d, %h, %l, %n, %p, %r, and %u.
+.Pp
+.Cm ProxyCommand
+accepts the tokens %%, %h, %p, and %r.
.Sh FILES
.Bl -tag -width Ds
.It Pa ~/.ssh/config
.Sh SEE ALSO
.Xr ssh 1
.Sh AUTHORS
+.An -nosplit
OpenSSH is a derivative of the original and free
-ssh 1.2.12 release by Tatu Ylonen.
-Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
-Theo de Raadt and Dug Song
+ssh 1.2.12 release by
+.An Tatu Ylonen .
+.An Aaron Campbell , Bob Beck , Markus Friedl ,
+.An Niels Provos , Theo de Raadt
+and
+.An Dug Song
removed many bugs, re-added newer features and
created OpenSSH.
-Markus Friedl contributed the support for SSH
-protocol versions 1.5 and 2.0.
+.An Markus Friedl
+contributed the support for SSH protocol versions 1.5 and 2.0.
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