svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
sshd_config(5)
reads configuration data from (or the file specified with on the
command line). The file contains keyword-argument pairs, one per
line. Unless noted otherwise, for each keyword, the first ob‐
tained value will be used. Lines starting with and empty lines
are interpreted as comments. Arguments may optionally be en‐
closed in double quotes in order to represent arguments contain‐
ing spaces. The possible keywords and their meanings are as fol‐
lows (note that keywords are case-insensitive and arguments are
case-sensitive): Specifies what environment variables sent by the
client will be copied into the session's See and in for how to
configure the client. The environment variable is always ac‐
cepted whenever the client requests a pseudo-terminal as it is
required by the protocol. Variables are specified by name, which
may contain the wildcard characters and Multiple environment
variables may be separated by whitespace or spread across multi‐
ple directives. Be warned that some environment variables could
be used to bypass restricted user environments. For this reason,
care should be taken in the use of this directive. The default
is not to accept any environment variables. Specifies which ad‐
dress family should be used by Valid arguments are (the default),
(use IPv4 only), or (use IPv6 only). Specifies whether forward‐
ing is permitted. The default is Note that disabling agent for‐
warding does not improve security unless users are also denied
shell access, as they can always install their own forwarders.
This keyword can be followed by a list of group name patterns,
separated by spaces. If specified, login is allowed only for
users whose primary group or supplementary group list matches one
of the patterns. Only group names are valid; a numerical group
ID is not recognized. By default, login is allowed for all
groups. The allow/deny groups directives are processed in the
following order: See PATTERNS in for more information on pat‐
terns. This keyword may appear multiple times in with each in‐
stance appending to the list. Specifies whether StreamLocal
(Unix-domain socket) forwarding is permitted. The available op‐
tions are (the default) or to allow StreamLocal forwarding, to
prevent all StreamLocal forwarding, to allow local (from the per‐
spective of forwarding only or to allow remote forwarding only.
Note that disabling StreamLocal forwarding does not improve secu‐
rity unless users are also denied shell access, as they can al‐
ways install their own forwarders. Specifies whether TCP for‐
warding is permitted. The available options are (the default) or
to allow TCP forwarding, to prevent all TCP forwarding, to allow
local (from the perspective of forwarding only or to allow remote
forwarding only. Note that disabling TCP forwarding does not im‐
prove security unless users are also denied shell access, as they
can always install their own forwarders. This keyword can be
followed by a list of user name patterns, separated by spaces.
If specified, login is allowed only for user names that match one
of the patterns. Only user names are valid; a numerical user ID
is not recognized. By default, login is allowed for all users.
If the pattern takes the form USER@HOST then USER and HOST are
separately checked, restricting logins to particular users from
particular hosts. HOST criteria may additionally contain ad‐
dresses to match in CIDR address/masklen format. The allow/deny
users directives are processed in the following order: See PAT‐
TERNS in for more information on patterns. This keyword may ap‐
pear multiple times in with each instance appending to the list.
Specifies the authentication methods that must be successfully
completed for a user to be granted access. This option must be
followed by one or more lists of comma-separated authentication
method names, or by the single string to indicate the default be‐
haviour of accepting any single authentication method. If the
default is overridden, then successful authentication requires
completion of every method in at least one of these lists. For
example, would require the user to complete public key authenti‐
cation, followed by either password or keyboard interactive au‐
thentication. Only methods that are next in one or more lists
are offered at each stage, so for this example it would not be
possible to attempt password or keyboard-interactive authentica‐
tion before public key. For keyboard interactive authentication
it is also possible to restrict authentication to a specific de‐
vice by appending a colon followed by the device identifier or
depending on the server configuration. For example, would re‐
strict keyboard interactive authentication to the device. If the
publickey method is listed more than once, verifies that keys
that have been used successfully are not reused for subsequent
authentications. For example, requires successful authentication
using two different public keys. Note that each authentication
method listed should also be explicitly enabled in the configura‐
tion. The available authentication methods are: (used for access
to password-less accounts when is enabled), and is not available
in FIPS-140 mode. Specifies a program to be used to look up the
user's public keys. The program must be owned by root, not
writable by group or others and specified by an absolute path.
Arguments to accept the tokens described in the section. If no
arguments are specified then the username of the target user is
used. The program should produce on standard output zero or more
lines of authorized_keys output (see in is tried after the usual
files and will not be executed if a matching key is found there.
By default, no is run. Specifies the user under whose account
the is run. It is recommended to use a dedicated user that has
no other role on the host than running authorized keys commands.
If is specified but is not, then will refuse to start. Specifies
the file that contains the public keys used for user authentica‐
tion. The format is described in the AUTHORIZED_KEYS FILE FORMAT
section of Arguments to may include wildcards and accept the to‐
kens described in the section. After expansion, is taken to be
an absolute path or one relative to the user's home directory.
Multiple files may be listed, separated by whitespace. Alter‐
nately this option may be set to to skip checking for user keys
in files. The default is Specifies a program to be used to gen‐
erate the list of allowed certificate principals as per The pro‐
gram must be owned by root, not writable by group or others and
specified by an absolute path. Arguments to accept the tokens
described in the section. If no arguments are specified then the
username of the target user is used. The program should produce
on standard output zero or more lines of output. If either or is
specified, then certificates offered by the client for authenti‐
cation must contain a principal that is listed. By default, no
is run. Specifies the user under whose account the is run. It
is recommended to use a dedicated user that has no other role on
the host than running authorized principals commands. If is
specified but is not, then will refuse to start. Specifies a
file that lists principal names that are accepted for certificate
authentication. When using certificates signed by a key listed
in this file lists names, one of which must appear in the cer‐
tificate for it to be accepted for authentication. Names are
listed one per line preceded by key options (as described in in
Empty lines and comments starting with are ignored. Arguments to
may include wildcards and accept the tokens described in the sec‐
tion. After expansion, is taken to be an absolute path or one
relative to the user's home directory. The default is i.e. not
to use a principals file – in this case, the username of the user
must appear in a certificate's principals list for it to be ac‐
cepted. Note that is only used when authentication proceeds us‐
ing a CA listed in and is not consulted for certification author‐
ities trusted via though the key option offers a similar facility
(see for details). The contents of the specified file are sent
to the remote user before authentication is allowed. If the ar‐
gument is then no banner is displayed. By default, no banner is
displayed. Specifies which algorithms are allowed for signing of
certificates by certificate authorities (CAs). The default is:
ssh-ed25519,ecdsa-sha2-nistp256, ecdsa-sha2-nistp384,ecdsa-
sha2-nistp521, sk-ssh-ed25519@openssh.com, sk-ecdsa-
sha2-nistp256@openssh.com, rsa-sha2-512,rsa-sha2-256 If the spec‐
ified list begins with a character, then the specified algorithms
will be appended to the default set instead of replacing them.
If the specified list begins with a character, then the specified
algorithms (including wildcards) will be removed from the default
set instead of replacing them. Certificates signed using other
algorithms will not be accepted for public key or host-based au‐
thentication. Specifies whether and how quickly should close in‐
active channels. Timeouts are specified as one or more pairs
separated by whitespace, where the must be the special keyword or
a channel type name from the list below, optionally containing
wildcard characters. The timeout value is specified in seconds
or may use any of the units documented in the section. For exam‐
ple, would cause interactive sessions to terminate after five
minutes of inactivity. Specifying a zero value disables the in‐
activity timeout. The special timeout applies to all active
channels, taken together. Traffic on any active channel will re‐
set the timeout, but when the timeout expires then all open chan‐
nels will be closed. Note that this global timeout is not
matched by wildcards and must be specified explicitly. The
available channel type names include: Open connections to Open
TCP or Unix socket (respectively) connections that have been es‐
tablished from an local forwarding, i.e. or Open TCP or Unix
socket (respectively) connections that have been established to
an listening on behalf of an remote forwarding, i.e. The interac‐
tive main session, including shell session, command execution,
etc. Open connections. Open X11 forwarding sessions. Note that
in all the above cases, terminating an inactive session does not
guarantee to remove all resources associated with the session,
e.g. shell processes or X11 clients relating to the session may
continue to execute. Moreover, terminating an inactive channel
or session does not necessarily close the SSH connection, nor
does it prevent a client from requesting another channel of the
same type. In particular, expiring an inactive forwarding ses‐
sion does not prevent another identical forwarding from being
subsequently created. The default is not to expire channels of
any type for inactivity. Specifies the pathname of a directory
to to after authentication. At session startup checks that all
components of the pathname are root-owned directories which are
not writable by group or others. After the chroot, changes the
working directory to the user's home directory. Arguments to ac‐
cept the tokens described in the section. The must contain the
necessary files and directories to support the user's session.
For an interactive session this requires at least a shell, typi‐
cally and basic nodes such as and devices. For file transfer
sessions using SFTP no additional configuration of the environ‐
ment is necessary if the in-process sftp-server is used, though
sessions which use logging may require inside the chroot direc‐
tory on some operating systems (see for details). For safety, it
is very important that the directory hierarchy be prevented from
modification by other processes on the system (especially those
outside the jail). Misconfiguration can lead to unsafe environ‐
ments which cannot detect. The default is indicating not to
Specifies the ciphers allowed. Multiple ciphers must be comma-
separated. If the specified list begins with a character, then
the specified ciphers will be appended to the default set instead
of replacing them. If the specified list begins with a charac‐
ter, then the specified ciphers (including wildcards) will be re‐
moved from the default set instead of replacing them. If the
specified list begins with a character, then the specified ci‐
phers will be placed at the head of the default set. The sup‐
ported ciphers are: 3des-cbc aes128-cbc aes192-cbc aes256-cbc
aes128-ctr aes192-ctr aes256-ctr aes128-gcm@openssh.com
aes256-gcm@openssh.com chacha20-poly1305@openssh.com The default
is: chacha20-poly1305@openssh.com,
aes128-gcm@openssh.com,aes256-gcm@openssh.com,
aes128-ctr,aes192-ctr,aes256-ctr The following ciphers are
FIPS-140 approved and are supported in FIPS-140 mode:
aes128-ctr,aes192-ctr,aes256-ctr,
aes128-gcm@openssh.com,aes256-gcm@openssh.com, aes128-cbc,3des-
cbc,aes192-cbc,aes256-cbc The list of available ciphers may also
be obtained using Sets the number of client alive messages which
may be sent without receiving any messages back from the client.
If this threshold is reached while client alive messages are be‐
ing sent, sshd will disconnect the client, terminating the ses‐
sion. It is important to note that the use of client alive mes‐
sages is very different from The client alive messages are sent
through the encrypted channel and therefore will not be spoofa‐
ble. The TCP keepalive option enabled by is spoofable. The
client alive mechanism is valuable when the client or server de‐
pend on knowing when a connection has become unresponsive. The
default value is 3. If is set to 15, and is left at the default,
unresponsive SSH clients will be disconnected after approximately
45 seconds. Setting a zero disables connection termination.
Sets a timeout interval in seconds after which if no data has
been received from the client, will send a message through the
encrypted channel to request a response from the client. The de‐
fault is 0, indicating that these messages will not be sent to
the client. Specifies whether compression is enabled after the
user has authenticated successfully. The argument must be (a
legacy synonym for or The default is This keyword can be followed
by a list of group name patterns, separated by spaces. Login is
disallowed for users whose primary group or supplementary group
list matches one of the patterns. Only group names are valid; a
numerical group ID is not recognized. By default, login is al‐
lowed for all groups. The allow/deny groups directives are
processed in the following order: See PATTERNS in for more infor‐
mation on patterns. This keyword may appear multiple times in
with each instance appending to the list. This keyword can be
followed by a list of user name patterns, separated by spaces.
Login is disallowed for user names that match one of the pat‐
terns. Only user names are valid; a numerical user ID is not
recognized. By default, login is allowed for all users. If the
pattern takes the form USER@HOST then USER and HOST are sepa‐
rately checked, restricting logins to particular users from par‐
ticular hosts. HOST criteria may additionally contain addresses
to match in CIDR address/masklen format. The allow/deny users
directives are processed in the following order: See PATTERNS in
for more information on patterns. This keyword may appear multi‐
ple times in with each instance appending to the list. Disables
all forwarding features, including X11, TCP and StreamLocal.
This option overrides all other forwarding-related options and
may simplify restricted configurations. Writes a temporary file
containing a list of authentication methods and public creden‐
tials (e.g. keys) used to authenticate the user. The location of
the file is exposed to the user session through the environment
variable. The default is Specifies the hash algorithm used when
logging key fingerprints. Valid options are: and The default is
In FIPS-140 mode the only supported option is Forces the execu‐
tion of the command specified by ignoring any command supplied by
the client and if present. The command is invoked by using the
user's login shell with the -c option. This applies to shell,
command, or subsystem execution. It is most useful inside a
block. The command originally supplied by the client is avail‐
able in the environment variable. Specifying a command of will
force the use of an in-process SFTP server that requires no sup‐
port files when used with The default is Specifies whether remote
hosts are allowed to connect to ports forwarded for the client.
By default, binds remote port forwardings to the loopback ad‐
dress. This prevents other remote hosts from connecting to for‐
warded ports. can be used to specify that sshd should allow re‐
mote port forwardings to bind to non-loopback addresses, thus al‐
lowing other hosts to connect. The argument may be to force re‐
mote port forwardings to be available to the local host only, to
force remote port forwardings to bind to the wildcard address, or
to allow the client to select the address to which the forwarding
is bound. The default is Specifies whether user authentication
based on GSSAPI is allowed. The default on Solaris is Specifies
whether to automatically destroy the user's credentials cache on
logout. The default is Specifies whether delegated GSSAPI cre‐
dentials are stored in default credential cache file (eg.
/tmp/krb5cc_100 for a user with UID 100) or in per-session non-
default credential cache (eg. /tmp/krb5cc_100_HwGrDC). Tickets
in non-default credential cache are not directly usable for ac‐
cessing krb5-protected NFS shares. Non-default credential cache
can be destroyed on logout based on setting however default cre‐
dential caches are never automatically destroyed by sshd on ses‐
sion logout. The default is Specifies whether key exchange based
on GSSAPI is allowed. GSSAPI key exchange doesn't rely on ssh
keys to verify host identity. The default is GSSAPI key exchange
is not available in FIPS-140 mode. Determines whether to be
strict about the identity of the GSSAPI acceptor a client authen‐
ticates against. If set to then the client must authenticate
against the host service on the current hostname. If set to then
the client may authenticate against any service key stored in the
machine's default store. This facility is provided to assist
with operation on multi homed machines. The default is Controls
whether the user's GSSAPI credentials should be updated following
a successful connection rekeying. This option can be used to ac‐
cepted renewed or updated credentials from a compatible client.
The default is For this to work needs to be enabled in the server
and also used by the client. The list of key exchange algorithms
that are accepted by GSSAPI key exchange. Possible values are
gss-gex-sha1-, gss-group1-sha1-, gss-group14-sha1-, gss-
group14-sha256-, gss-group16-sha512-, gss-nistp256-sha256-, gss-
curve25519-sha256- The default is This option only applies to
protocol version 2 connections using GSSAPI. Specifies the sig‐
nature algorithms that will be accepted for hostbased authentica‐
tion as a list of comma-separated patterns. Alternately if the
specified list begins with a character, then the specified signa‐
ture algorithms will be appended to the default set instead of
replacing them. If the specified list begins with a character,
then the specified signature algorithms (including wildcards)
will be removed from the default set instead of replacing them.
If the specified list begins with a character, then the specified
signature algorithms will be placed at the head of the default
set. The default for this option is: ssh-ed25519-cert-
v01@openssh.com, ecdsa-sha2-nistp256-cert-v01@openssh.com, ecdsa-
sha2-nistp384-cert-v01@openssh.com, ecdsa-sha2-nistp521-cert-
v01@openssh.com, sk-ssh-ed25519-cert-v01@openssh.com, sk-ecdsa-
sha2-nistp256-cert-v01@openssh.com, rsa-sha2-512-cert-
v01@openssh.com, rsa-sha2-256-cert-v01@openssh.com, ssh-ed25519,
ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, sk-
ssh-ed25519@openssh.com, sk-ecdsa-sha2-nistp256@openssh.com, rsa-
sha2-512,rsa-sha2-256 The list of available signature algorithms
may also be obtained using This was formerly named HostbasedAc‐
ceptedKeyTypes. Specifies whether rhosts or /etc/hosts.equiv au‐
thentication together with successful public key client host au‐
thentication is allowed (host-based authentication). The default
is Specifies whether or not the server will attempt to perform a
reverse name lookup when matching the name in the and files dur‐
ing A setting of means that uses the name supplied by the client
rather than attempting to resolve the name from the TCP connec‐
tion itself. The default is Specifies a file containing a public
host certificate. The certificate's public key must match a pri‐
vate host key already specified by The default behaviour of is
not to load any certificates. Specifies a file containing a pri‐
vate host key used by SSH. The defaults are and Note that will
refuse to use a file if it is group/world-accessible and that the
option restricts which of the keys are actually used by It is
possible to have multiple host key files. It is also possible to
specify public host key files instead. In this case operations
on the private key will be delegated to an Identifies the UNIX-
domain socket used to communicate with an agent that has access
to the private host keys. If the string is specified, the loca‐
tion of the socket will be read from the environment variable.
Specifies the host key signature algorithms that the server of‐
fers. The default for this option is: ssh-ed25519-cert-
v01@openssh.com, ecdsa-sha2-nistp256-cert-v01@openssh.com, ecdsa-
sha2-nistp384-cert-v01@openssh.com, ecdsa-sha2-nistp521-cert-
v01@openssh.com, sk-ssh-ed25519-cert-v01@openssh.com, sk-ecdsa-
sha2-nistp256-cert-v01@openssh.com, rsa-sha2-512-cert-
v01@openssh.com, rsa-sha2-256-cert-v01@openssh.com, ssh-ed25519,
ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, sk-
ssh-ed25519@openssh.com, sk-ecdsa-sha2-nistp256@openssh.com, rsa-
sha2-512,rsa-sha2-256 The list of available signature algorithms
may also be obtained using Specifies whether to ignore per-user
and files during The system-wide and are still used regardless of
this setting. Accepted values are (the default) to ignore all
per-user files, to allow the use of but to ignore or to allow
both and Specifies whether should ignore the user's during and
use only the system-wide known hosts file The default is Include
the specified configuration file(s). Multiple pathnames may be
specified and each pathname may contain wildcards that will be
expanded and processed in lexical order. Files without absolute
paths are assumed to be in An directive may appear inside a block
to perform conditional inclusion. Specifies the value for the
connection. Accepted values are a numeric value, or to use the
operating system default. This option may take one or two argu‐
ments, 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 de‐
fault is (Expedited Forwarding) for interactive sessions and (the
operating system default) for non-interactive sessions. Speci‐
fies whether to allow keyboard-interactive authentication. All
authentication styles from are supported. The default is The ar‐
gument to this keyword must be or is a deprecated alias for this.
Specifies whether the password provided by the user for will be
validated through the Kerberos KDC. To use this option, the
server needs a Kerberos servtab which allows the verification of
the KDC's identity. The default is If AFS is active and the user
has a Kerberos 5 TGT, attempt to acquire an AFS token before ac‐
cessing the user's home directory. The default is If password
authentication through Kerberos fails then the password will be
validated via any additional local mechanism such as The default
is Specifies whether to automatically destroy the user's ticket
cache file on logout. The default is Specifies the permitted KEX
(Key Exchange) algorithms that the server will offer to clients.
The ordering of this list is not important, as the client speci‐
fies the preference order. Multiple algorithms must be comma-
separated. If the specified list begins with a character, then
the specified algorithms will be appended to the default set in‐
stead of replacing them. If the specified list begins with a
character, then the specified algorithms (including wildcards)
will be removed from the default set instead of replacing them.
If the specified list begins with a character, then the specified
algorithms will be placed at the head of the default set. The
supported algorithms are: curve25519-sha256
curve25519-sha256@libssh.org diffie-hellman-group1-sha1 diffie-
hellman-group14-sha1 diffie-hellman-group14-sha256 diffie-hell‐
man-group16-sha512 diffie-hellman-group18-sha512 diffie-hellman-
group-exchange-sha1 diffie-hellman-group-exchange-sha256 ecdh-
sha2-nistp256 ecdh-sha2-nistp384 ecdh-sha2-nistp521
mlkem768x25519-sha256 sntrup761x25519-sha512
sntrup761x25519-sha512@openssh.com The default is:
mlkem768x25519-sha256,
sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com,
curve25519-sha256,curve25519-sha256@libssh.org, ecdh-
sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521 The list of
supported key exchange algorithms may also be obtained using
Specifies the local addresses should listen on. The following
forms may be used: The optional qualifier requests listen in an
explicit routing domain. If is not specified, sshd will listen
on the address and all options specified. The default is to lis‐
ten on all local addresses on the current default routing domain.
Multiple options are permitted. For more information on routing
domains, see The server disconnects after this time if the user
has not successfully logged in. If the value is 0, there is no
time limit. The default is 120 seconds. Gives the verbosity
level that is used when logging messages from The possible values
are: QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2,
and DEBUG3. The default is INFO. DEBUG and DEBUG1 are equiva‐
lent. DEBUG2 and DEBUG3 each specify higher levels of debugging
output. Logging with a DEBUG level violates the privacy of users
and is not recommended. Specify one or more overrides to An
override consists of one or more pattern lists that matches the
source file, function and line number to force detailed logging
for. For example, an override pattern of: kex.c:*:1000,*:kex_ex‐
change_identification():*,packet.c:* would enable detailed log‐
ging for line 1000 of everything in the function, and all code in
the file. This option is intended for debugging and no overrides
are enabled by default. Specifies the available MAC (message au‐
thentication code) algorithms. The MAC algorithm is used for
data integrity protection. Multiple algorithms must be comma-
separated. If the specified list begins with a character, then
the specified algorithms will be appended to the default set in‐
stead of replacing them. If the specified list begins with a
character, then the specified algorithms (including wildcards)
will be removed from the default set instead of replacing them.
If the specified list begins with a character, then the specified
algorithms will be placed at the head of the default set. The
algorithms that contain calculate the MAC after encryption (en‐
crypt-then-mac). These are considered safer and their use recom‐
mended. The supported MACs are: hmac-sha1 hmac-sha1-96 hmac-
sha2-256 hmac-sha2-512 umac-64@openssh.com umac-128@openssh.com
hmac-sha1-etm@openssh.com hmac-sha1-96-etm@openssh.com hmac-
sha2-256-etm@openssh.com hmac-sha2-512-etm@openssh.com
umac-64-etm@openssh.com umac-128-etm@openssh.com The default is:
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 The following MACs are
FIPS-140 approved and are supported in FIPS-140 mode: hmac-
sha2-256-etm@openssh.com, hmac-sha2-512-etm@openssh.com, hmac-
sha2-256,hmac-sha2-512, hmac-sha1-etm@openssh.com, hmac-
sha1-96-etm@openssh.com hmac-sha1,hmac-sha1-96 The list of avail‐
able MAC algorithms may also be obtained using Introduces a con‐
ditional block. If all of the criteria on the line are satis‐
fied, the keywords on the following lines override those set in
the global section of the config file, until either another line
or the end of the file. If a keyword appears in multiple blocks
that are satisfied, only the first instance of the keyword is ap‐
plied. The arguments to are one or more criteria-pattern pairs
or one of the single token criteria: which matches all criteria,
or which matches when the requested user-name does not match any
known account. The available criteria are and (with representing
the on which the connection was received). The match patterns
may consist of single entries or comma-separated lists and may
use the wildcard and negation operators described in the section
of The patterns in an criteria may additionally contain addresses
to match in CIDR address/masklen format, such as 192.0.2.0/24 or
2001:db8::/32. Note that the mask length provided must be con‐
sistent with the address - it is an error to specify a mask
length that is too long for the address or one with bits set in
this host portion of the address. For example, 192.0.2.0/33 and
192.0.2.0/8, respectively. The keyword matches against the ver‐
sion string of for example Only a subset of keywords may be used
on the lines following a keyword. Available keywords are and
Specifies the maximum number of authentication attempts permitted
per connection. Once the number of failures reaches half this
value, additional failures are logged. The default is 6. Speci‐
fies the maximum number of open shell, login or subsystem (e.g.
sftp) sessions permitted per network connection. Multiple ses‐
sions may be established by clients that support connection mul‐
tiplexing. Setting to 1 will effectively disable session multi‐
plexing, whereas setting it to 0 will prevent all shell, login
and subsystem sessions while still permitting forwarding. The
default is 10. Specifies the maximum number of concurrent unau‐
thenticated connections to the SSH daemon. Additional connec‐
tions will be dropped until authentication succeeds or the ex‐
pires for a connection. The default is 10:30:100. Alterna‐
tively, random early drop can be enabled by specifying the three
colon separated values start:rate:full (e.g. "10:30:60"). will
refuse connection attempts with a probability of rate/100 (30%)
if there are currently start (10) unauthenticated connections.
The probability increases linearly and all connection attempts
are refused if the number of unauthenticated connections reaches
full (60). Specifies the file that contains the Diffie-Hellman
groups used for the and key exchange methods. The default is
Specifies the PAM service name for the PAM session. The PAMServi‐
ceName and PAMServicePrefix options are mutually exclusive and if
both set, sshd does not start. If this option is set the service
name is the same for all user authentication methods. The option
has no default value. See PAMServicePrefix for more information.
Specifies the PAM service name prefix for service names used for
individual user authentication methods. The default is sshd. The
PAMServiceName and PAMServicePrefix options are mutually exclu‐
sive and if both set, sshd does not start. For example, if this
option is set to admincli, the service name for the keyboard-in‐
teractive authentication method is admincli-kbdint instead of the
default sshd-kbdint. Specifies whether password authentication
is allowed. The default is When password authentication is al‐
lowed, it specifies whether the server allows login to accounts
with empty password strings. The default is Specifies the ad‐
dresses/ports on which a remote TCP port forwarding may listen.
The listen specification must be one of the following forms: Mul‐
tiple permissions may be specified by separating them with white‐
space. An argument of can be used to remove all restrictions and
permit any listen requests. An argument of can be used to pro‐
hibit all listen requests. The host name may contain wildcards
as described in the PATTERNS section in The wildcard can also be
used in place of a port number to allow all ports. By default
all port forwarding listen requests are permitted. Note that the
option may further restrict which addresses may be listened on.
Note also that will request a listen host of if no listen host
was specifically requested, and this name is treated differently
to explicit localhost addresses of and Specifies the destinations
to which TCP port forwarding is permitted. The forwarding speci‐
fication must be one of the following forms: Multiple forwards
may be specified by separating them with whitespace. An argument
of can be used to remove all restrictions and permit any forward‐
ing requests. An argument of can be used to prohibit all for‐
warding requests. The wildcard can be used for host or port to
allow all hosts or ports respectively. Otherwise, no pattern
matching or address lookups are performed on supplied names. By
default all port forwarding requests are permitted. Specifies
whether root can log in using The argument must be or The default
is If this option is set to (or its deprecated alias, password
and keyboard-interactive authentication are disabled for root.
If this option is set to root login with public key authentica‐
tion will be allowed, but only if the option has been specified
(which may be useful for taking remote backups even if root login
is normally not allowed). All other authentication methods are
disabled for root. If this option is set to root is not allowed
to log in. Specifies whether allocation is permitted. The de‐
fault is Specifies whether device forwarding is allowed. The ar‐
gument must be (layer 3), (layer 2), or Specifying permits both
and The default is Independent of this setting, the permissions
of the selected device must allow access to the user. Specifies
whether and options in are processed by Valid options are or a
pattern-list specifying which environment variable names to ac‐
cept (for example The default is Enabling environment processing
may enable users to bypass access restrictions in some configura‐
tions using mechanisms such as Specifies whether any file is exe‐
cuted. The default is Specifies the number of unauthenticated
connections allowed from a given source address, or if there is
no limit. This limit is applied in addition to whichever is
lower. The default is Specifies the number of bits of source ad‐
dress that are grouped together for the purposes of applying Per‐
SourceMaxStartups limits. Values for IPv4 and optionally IPv6
may be specified, separated by a colon. The default is which
means each address is considered individually. Controls penal‐
ties for various conditions that may represent attacks on If a
penalty is enforced against a client then its source address and
any others in the same network, as defined by will be refused
connection for a period. A penalty doesn't affect concurrent
connections in progress, but multiple penalties from the same
source from concurrent connections will accumulate up to a maxi‐
mum. Conversely, penalties are not applied until a minimum
threshold time has been accumulated. Penalties are enabled by
default with the default settings listed below but may disabled
using the keyword. The defaults may be overridden by specifying
one or more of the keywords below, separated by whitespace. All
keywords accept arguments, e.g. Specifies how long to refuse
clients that cause a crash of Specifies how long to refuse
clients that disconnect after making one or more unsuccessful au‐
thentication attempts (default: 5s). Specifies how long to
refuse clients that were administratively prohibited connection
via the option (default: 10s). Specifies how long to refuse
clients that disconnect without attempting authentication (de‐
fault: 1s). This timeout should be used cautiously otherwise it
may penalise legitimate scanning tools such as Specifies how long
to refuse clients that fail to authenticate after (default: 10s).
Specifies the maximum time a particular source address range will
be refused access for (default: 10m). Repeated penalties will
accumulate up to this maximum. Specifies the minimum penalty
that must accrue before enforcement begins (default: 15s). Spec‐
ifies the maximum number of client IPv4 and IPv6 address ranges
to track for penalties (default: 65536 for both). Controls how
the server behaves when or is exceeded. There are two operating
modes: which denies all incoming connections other than those ex‐
empted via until a penalty expires, and which allows new connec‐
tions by removing existing penalties early (default: permissive).
Note that client penalties below the threshold count against the
total number of tracked penalties. IPv4 and IPv6 addresses are
tracked separately, so an overflow in one will not affect the
other. Allows specifying a different overflow mode for IPv6 ad‐
dresses. The default it to use the same overflow mode as was
specified for IPv4. Specifies a comma-separated list of ad‐
dresses to exempt from penalties. This list may contain wild‐
cards and CIDR address/masklen ranges. Note that the mask length
provided must be consistent with the address - it is an error to
specify a mask length that is too long for the address or one
with bits set in this host portion of the address. For example,
192.0.2.0/33 and 192.0.2.0/8, respectively. The default is not
to exempt any addresses. Specifies the file that contains the
process ID of the SSH daemon, or to not write one. The default
is Specifies the port number that listens on. The default is 22.
Multiple options of this type are permitted. See also Specifies
whether should print the date and time of the last user login
when a user logs in interactively. On Solaris this option is al‐
ways ignored since pam_unix_session(7) reports the last login
time. Specifies whether should print when a user logs in inter‐
actively. (On some systems it is also printed by the shell, or
equivalent.) The default is Specifies the signature algorithms
that will be accepted for public key authentication as a list of
comma-separated patterns. Alternately if the specified list be‐
gins with a character, then the specified algorithms will be ap‐
pended to the default set instead of replacing them. If the
specified list begins with a character, then the specified algo‐
rithms (including wildcards) will be removed from the default set
instead of replacing them. If the specified list begins with a
character, then the specified algorithms will be placed at the
head of the default set. The default for this option is: ssh-
ed25519-cert-v01@openssh.com, ecdsa-sha2-nistp256-cert-
v01@openssh.com, ecdsa-sha2-nistp384-cert-v01@openssh.com, ecdsa-
sha2-nistp521-cert-v01@openssh.com, sk-ssh-ed25519-cert-
v01@openssh.com, sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
rsa-sha2-512-cert-v01@openssh.com, rsa-sha2-256-cert-
v01@openssh.com, ssh-ed25519, ecdsa-sha2-nistp256,ecdsa-
sha2-nistp384,ecdsa-sha2-nistp521, sk-ssh-ed25519@openssh.com,
sk-ecdsa-sha2-nistp256@openssh.com, rsa-sha2-512,rsa-sha2-256 The
list of available signature algorithms may also be obtained using
Sets one or more public key authentication options. The sup‐
ported keywords are: (the default; indicating no additional op‐
tions are enabled), and The option causes public key authentica‐
tion using a FIDO authenticator algorithm (i.e. or to always re‐
quire the signature to attest that a physically present user ex‐
plicitly confirmed the authentication (usually by touching the
authenticator). By default, requires user presence unless over‐
ridden with an authorized_keys option. The flag disables this
override. The option requires a FIDO key signature attest that
the user was verified, e.g. via a PIN. Neither the or options
have any effect for other, non-FIDO, public key types. Specifies
whether public key authentication is allowed. The default is In‐
dicates that should unconditionally terminate the connection.
Additionally, a penalty may be recorded against the source of the
connection if are enabled. This option is only really useful in
a block. Specifies the maximum amount of data that may be trans‐
mitted or received before the session key is renegotiated, op‐
tionally followed by a maximum amount of time that may pass be‐
fore the session key is renegotiated. The first argument is
specified in bytes and may have a suffix of or to indicate Kilo‐
bytes, Megabytes, or Gigabytes, respectively. The default is be‐
tween and depending on the cipher. The optional second value is
specified in seconds and may use any of the units documented in
the section. The default value for is 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. Specifies
the minimum RSA key size (in bits) that will accept. User and
host-based authentication keys smaller than this limit will be
refused. The default is bits. Note that this limit may only be
raised from the default. Specifies revoked public keys file, or
to not use one. Keys listed in this file will be refused for
public key authentication. Note that if this file is not read‐
able, then public key authentication will be refused for all
users. Keys may be specified as a text file, listing one public
key per line, or as an OpenSSH Key Revocation List (KRL) as gen‐
erated by For more information on KRLs, see the KEY REVOCATION
LISTS section in Specifies an explicit routing domain that is ap‐
plied after authentication has completed. The user session, as
well as any forwarded or listening IP sockets, will be bound to
this If the routing domain is set to then the domain in which the
incoming connection was received will be applied. Specifies a
path to a library that will be used when loading FIDO authentica‐
tor-hosted keys, overriding the default of using the built-in USB
HID support. Specifies one or more environment variables to set
in child sessions started by as The environment value may be
quoted (e.g. if it contains whitespace characters). Environment
variables set by override the default environment and any vari‐
ables specified by the user via or Overrides the default path to
the binary that is invoked to complete user authentication. The
default is This option is intended for use by tests. Overrides
the default path to the binary that is invoked to handle each
connection. The default is This option is intended for use by
tests. Sets the octal file creation mode mask 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. The default value is 0177, which creates a Unix-do‐
main 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. Specifies whether to remove an existing
Unix-domain socket file for local or remote port forwarding be‐
fore creating a new one. If the socket file already exists and
is not enabled, 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. The argument must be or The de‐
fault is Specifies whether should check file modes and ownership
of the user's files and home directory before accepting login.
This is normally desirable because novices sometimes accidentally
leave their directory or files world-writable. The default is
Note that this does not apply to whose permissions and ownership
are checked unconditionally. Configures an external subsystem
(e.g. file transfer daemon). Arguments should be a subsystem
name and a command (with optional arguments) to execute upon sub‐
system request. The command implements the SFTP file transfer
subsystem. Alternately the name implements an in-process SFTP
server. This may simplify configurations using to force a dif‐
ferent filesystem root on clients. It accepts the same command
line arguments as and even though it is in-process, settings such
as or do not apply to it and must be set explicitly via command
line arguments. By default no subsystems are defined. Gives the
facility code that is used when logging messages from The possi‐
ble values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, LO‐
CAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. The default is AUTH.
Specifies whether the system should send TCP keepalive messages
to the other side. If they are sent, death of the connection or
crash of one of the machines will be properly noticed. However,
this means that connections will die if the route is down tem‐
porarily, and some people find it annoying. On the other hand,
if TCP keepalives are not sent, sessions may hang indefinitely on
the server, leaving users and consuming server resources. The
default is (to send TCP keepalive messages), and the server will
notice if the network goes down or the client host crashes. This
avoids infinitely hanging sessions. To disable TCP keepalive
messages, the value should be set to Specifies a file containing
public keys of certificate authorities that are trusted to sign
user certificates for authentication, or to not use one. Keys
are listed one per line; empty lines and comments starting with
are allowed. If a certificate is presented for authentication
and has its signing CA key listed in this file, then it may be
used for authentication for any user listed in the certificate's
principals list. Note that certificates that lack a list of
principals will not be permitted for authentication using For
more details on certificates, see the CERTIFICATES section in
Specifies whether and how quickly should close client connections
with no open channels. Open channels include active shell, com‐
mand execution or subsystem sessions, connected network, socket,
agent or X11 forwardings. Forwarding listeners, such as those
from the flag, are not considered as open channels and do not
prevent the timeout. The timeout value is specified in seconds
or may use any of the units documented in the section. Note that
this timeout starts when the client connection completes user au‐
thentication but before the client has an opportunity to open any
channels. Caution should be used when using short timeout val‐
ues, as they may not provide sufficient time for the client to
request and open its channels before terminating the connection.
The default is to never expire connections for having no open
channels. This option may be useful in conjunction with Speci‐
fies whether should look up the remote host name, and to check
that the resolved host name for the remote IP address maps back
to the very same IP address. If this option is set to (the de‐
fault) then only addresses and not host names may be used in and
directives. Enables the Pluggable Authentication Module inter‐
face. If set to this will enable PAM authentication using and in
addition to PAM account and session module processing for all au‐
thentication types. Because PAM keyboard-interactive authentica‐
tion usually serves an equivalent role to password authentica‐
tion, you should disable either or If is enabled, you will not be
able to run as a non-root user. On Solaris, this option is al‐
ways enabled. Optionally specifies additional text to append to
the SSH protocol banner sent by the server upon connection. The
default is Specifies the first display number available for X11
forwarding. This prevents sshd from interfering with real X11
servers. The default is 10. Specifies whether X11 forwarding is
permitted. The argument must be or The default on Solaris is
When X11 forwarding is enabled, there may be additional exposure
to the server and to client displays if the proxy display is con‐
figured to listen on the wildcard address (see though this is not
the default. Additionally, the authentication spoofing and au‐
thentication data verification and substitution occur on the
client side. The security risk of using X11 forwarding is that
the client's X11 display server may be exposed to attack when the
SSH client requests forwarding (see the warnings for in A system
administrator may have a stance in which they want to protect
clients that may expose themselves to attack by unwittingly re‐
questing X11 forwarding, which can warrant a setting. Note that
disabling X11 forwarding does not prevent users from forwarding
X11 traffic, as users can always install their own forwarders.
Specifies whether should bind the X11 forwarding server to the
loopback address or to the wildcard address. By default, sshd
binds the forwarding server to the loopback address and sets the
hostname part of the environment variable to This prevents remote
hosts from connecting to the proxy display. However, some older
X11 clients may not function with this configuration. may be set
to to specify that the forwarding server should be bound to the
wildcard address. The argument must be or The default is Speci‐
fies the full pathname of the program, or to not use one. The
default is command-line arguments and configuration file options
that specify time may be expressed using a sequence of the form:
where is a positive integer value and is one of the following:
seconds seconds minutes hours days weeks Each member of the se‐
quence is added together to calculate the total time value. Time
format examples: 600 seconds (10 minutes) 10 minutes 1 hour 30
minutes (90 minutes) Arguments to some keywords can make use of
tokens, which are expanded at runtime: A literal Identifies the
connection endpoints, containing four space-separated values:
client address, client port number, server address, and server
port number. The routing domain in which the incoming connection
was received. The fingerprint of the CA key. The fingerprint of
the key or certificate. The home directory of the user. The key
ID in the certificate. The base64-encoded CA key. The
base64-encoded key or certificate for authentication. The serial
number of the certificate. The type of the CA key. The key or
certificate type. The numeric user ID of the target user. The
username. accepts the tokens %%, %C, %D, %f, %h, %k, %t, %U, and
%u. accepts the tokens %%, %h, %U, and %u. accepts the tokens
%%, %C, %D, %F, %f, %h, %i, %K, %k, %s, %T, %t, %U, and %u. ac‐
cepts the tokens %%, %h, %U, and %u. accepts the tokens %%, %h,
%U, and %u. accepts the token %D. Contains configuration data
for This file should be writable by root only, but it is recom‐
mended (though not necessary) that it be world-readable.
See for descriptions of the following attributes:
box; cbp-1 | cbp-1 l | l . ATTRIBUTE TYPE ATTRIBUTE VALUE =
Availability service/network/ssh = Stability Pass-
through uncommitted OpenSSH is a derivative of the original and
free ssh 1.2.12 release by and removed many bugs, re-added newer
features and created OpenSSH. contributed the support for SSH
protocol versions 1.5 and 2.0. and contributed support for priv‐
ilege separation.
Source code for open source software components in Oracle Solaris
can be found at https://www.oracle.com/downloads/opensource/so‐
laris-source-code-downloads.html.
This software was built from source available at:
https://github.com/oracle/solaris-userland
The original community source was downloaded from:
https://mir‐
rors.sonic.net/pub/OpenBSD/OpenSSH/portable/openssh-10.2p1.tar.gz
Further information about this software can be found on the open
source community website at https://www.openssh.com/.