external/openssh: update to 6.8p1.
In preparation for some updates to external/openssh to make it work with
BoringSSL, this change updates the code to a recent version. The current
version (5.9p1) is coming up on four years old now.
* Confirmed that f5c67b478bef9992de9e9ec91ce10af4f6205e0d matches
OpenSSH 5.9p1 exactly (save for the removal of the scard
subdirectory).
* Downloaded openssh-6.8p1.tar.gz (SHA256:
3ff64ce73ee124480b5bf767b9830d7d3c03bbcb6abe716b78f0192c37ce160e)
and verified with PGP signature. (I've verified Damien's key in
person previously.)
* Applied changes between f5c67b478bef9992de9e9ec91ce10af4f6205e0d and
OpenSSH 5.9p1 to 6.8p1 and updated the build as best I can. The
ugliest change is probably the duplication of umac.c to umac128.c
because Android conditionally compiles that file twice. See the
comment in those files.
Change-Id: I63cb07a8118afb5a377f116087a0882914cea486
diff --git a/sshd_config.0 b/sshd_config.0
index e19ca87..be48e13 100644
--- a/sshd_config.0
+++ b/sshd_config.0
@@ -1,7 +1,7 @@
-SSHD_CONFIG(5) OpenBSD Programmer's Manual SSHD_CONFIG(5)
+SSHD_CONFIG(5) File Formats Manual SSHD_CONFIG(5)
NAME
- sshd_config - OpenSSH SSH daemon configuration file
+ sshd_config M-bM-^@M-^S OpenSSH SSH daemon configuration file
SYNOPSIS
/etc/ssh/sshd_config
@@ -9,7 +9,7 @@
DESCRIPTION
sshd(8) reads configuration data from /etc/ssh/sshd_config (or the file
specified with -f on the command line). The file contains keyword-
- argument pairs, one per line. Lines starting with `#' and empty lines
+ argument pairs, one per line. Lines starting with M-bM-^@M-^X#M-bM-^@M-^Y and empty lines
are interpreted as comments. Arguments may optionally be enclosed in
double quotes (") in order to represent arguments containing spaces.
@@ -22,7 +22,7 @@
ssh_config(5) for how to configure the client. Note that
environment passing is only supported for protocol 2. Variables
are specified by name, which may contain the wildcard characters
- `*' and `?'. Multiple environment variables may be separated by
+ M-bM-^@M-^X*M-bM-^@M-^Y and M-bM-^@M-^X?M-bM-^@M-^Y. Multiple environment variables may be separated by
whitespace or spread across multiple AcceptEnv directives. Be
warned that some environment variables could be used to bypass
restricted user environments. For this reason, care should be
@@ -31,14 +31,14 @@
AddressFamily
Specifies which address family should be used by sshd(8). Valid
- arguments are ``any'', ``inet'' (use IPv4 only), or ``inet6''
- (use IPv6 only). The default is ``any''.
+ arguments are M-bM-^@M-^\anyM-bM-^@M-^], M-bM-^@M-^\inetM-bM-^@M-^] (use IPv4 only), or M-bM-^@M-^\inet6M-bM-^@M-^] (use IPv6
+ only). The default is M-bM-^@M-^\anyM-bM-^@M-^].
AllowAgentForwarding
Specifies whether ssh-agent(1) forwarding is permitted. The
- default is ``yes''. Note that disabling agent forwarding does
- not improve security unless users are also denied shell access,
- as they can always install their own forwarders.
+ default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that disabling agent forwarding does not
+ improve security unless users are also denied shell access, as
+ they can always install their own forwarders.
AllowGroups
This keyword can be followed by a list of group name patterns,
@@ -53,10 +53,24 @@
See PATTERNS in ssh_config(5) for more information on patterns.
AllowTcpForwarding
- Specifies whether TCP forwarding is permitted. The default is
- ``yes''. Note that disabling TCP forwarding does not improve
- security unless users are also denied shell access, as they can
- always install their own forwarders.
+ Specifies whether TCP forwarding is permitted. The available
+ options are M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\allM-bM-^@M-^] to allow TCP forwarding, M-bM-^@M-^\noM-bM-^@M-^] to
+ prevent all TCP forwarding, M-bM-^@M-^\localM-bM-^@M-^] to allow local (from the
+ perspective of ssh(1)) forwarding only or M-bM-^@M-^\remoteM-bM-^@M-^] to allow
+ remote forwarding only. The default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that
+ disabling TCP forwarding does not improve security unless users
+ are also denied shell access, as they can always install their
+ own forwarders.
+
+ AllowStreamLocalForwarding
+ Specifies whether StreamLocal (Unix-domain socket) forwarding is
+ permitted. The available options are M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\allM-bM-^@M-^] to allow
+ StreamLocal forwarding, M-bM-^@M-^\noM-bM-^@M-^] to prevent all StreamLocal
+ forwarding, M-bM-^@M-^\localM-bM-^@M-^] to allow local (from the perspective of
+ ssh(1)) forwarding only or M-bM-^@M-^\remoteM-bM-^@M-^] to allow remote forwarding
+ only. The default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that disabling StreamLocal
+ forwarding does not improve security unless users are also denied
+ shell access, as they can always install their own forwarders.
AllowUsers
This keyword can be followed by a list of user name patterns,
@@ -71,6 +85,60 @@
See PATTERNS in ssh_config(5) for more information on patterns.
+ AuthenticationMethods
+ 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 comma-separated lists of authentication
+ method names. Successful authentication requires completion of
+ every method in at least one of these lists.
+
+ For example, an argument of M-bM-^@M-^\publickey,password
+ publickey,keyboard-interactiveM-bM-^@M-^] would require the user to
+ complete public key authentication, followed by either password
+ or keyboard interactive authentication. 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 authentication before public key.
+
+ For keyboard interactive authentication it is also possible to
+ restrict authentication to a specific device by appending a colon
+ followed by the device identifier M-bM-^@M-^\bsdauthM-bM-^@M-^], M-bM-^@M-^\pamM-bM-^@M-^], or M-bM-^@M-^\skeyM-bM-^@M-^],
+ depending on the server configuration. For example,
+ M-bM-^@M-^\keyboard-interactive:bsdauthM-bM-^@M-^] would restrict keyboard
+ interactive authentication to the M-bM-^@M-^\bsdauthM-bM-^@M-^] device.
+
+ If the M-bM-^@M-^\publickeyM-bM-^@M-^] method is listed more than once, sshd(8)
+ verifies that keys that have been used successfully are not
+ reused for subsequent authentications. For example, an
+ AuthenticationMethods of M-bM-^@M-^\publickey,publickeyM-bM-^@M-^] will require
+ successful authentication using two different public keys.
+
+ This option is only available for SSH protocol 2 and will yield a
+ fatal error if enabled if protocol 1 is also enabled. Note that
+ each authentication method listed should also be explicitly
+ enabled in the configuration. The default is not to require
+ multiple authentication; successful completion of a single
+ authentication method is sufficient.
+
+ AuthorizedKeysCommand
+ Specifies a program to be used to look up the user's public keys.
+ The program must be owned by root and not writable by group or
+ others. It will be invoked with a single argument of the
+ username being authenticated, and should produce on standard
+ output zero or more lines of authorized_keys output (see
+ AUTHORIZED_KEYS in sshd(8)). If a key supplied by
+ AuthorizedKeysCommand does not successfully authenticate and
+ authorize the user then public key authentication continues using
+ the usual AuthorizedKeysFile files. By default, no
+ AuthorizedKeysCommand is run.
+
+ AuthorizedKeysCommandUser
+ Specifies the user under whose account the AuthorizedKeysCommand
+ is run. It is recommended to use a dedicated user that has no
+ other role on the host than running authorized keys commands. If
+ AuthorizedKeysCommand is specified but AuthorizedKeysCommandUser
+ is not, then sshd(8) will refuse to start.
+
AuthorizedKeysFile
Specifies the file that contains the public keys that can be used
for user authentication. The format is described in the
@@ -83,7 +151,7 @@
AuthorizedKeysFile is taken to be an absolute path or one
relative to the user's home directory. Multiple files may be
listed, separated by whitespace. The default is
- ``.ssh/authorized_keys .ssh/authorized_keys2''.
+ M-bM-^@M-^\.ssh/authorized_keys .ssh/authorized_keys2M-bM-^@M-^].
AuthorizedPrincipalsFile
Specifies a file that lists principal names that are accepted for
@@ -92,7 +160,7 @@
which must appear in the certificate for it to be accepted for
authentication. Names are listed one per line preceded by key
options (as described in AUTHORIZED_KEYS FILE FORMAT in sshd(8)).
- Empty lines and comments starting with `#' are ignored.
+ Empty lines and comments starting with M-bM-^@M-^X#M-bM-^@M-^Y are ignored.
AuthorizedPrincipalsFile may contain tokens of the form %T which
are substituted during connection setup. The following tokens
@@ -102,31 +170,32 @@
AuthorizedPrincipalsFile is taken to be an absolute path or one
relative to the user's home directory.
- The default is 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 accepted. Note that AuthorizedPrincipalsFile
- is only used when authentication proceeds using a CA listed in
- TrustedUserCAKeys and is not consulted for certification
- authorities trusted via ~/.ssh/authorized_keys, though the
- principals= key option offers a similar facility (see sshd(8) for
- details).
+ The default is M-bM-^@M-^\noneM-bM-^@M-^], i.e. not to use a principals file M-bM-^@M-^S in
+ this case, the username of the user must appear in a
+ certificate's principals list for it to be accepted. Note that
+ AuthorizedPrincipalsFile is only used when authentication
+ proceeds using a CA listed in TrustedUserCAKeys and is not
+ consulted for certification authorities trusted via
+ ~/.ssh/authorized_keys, though the principals= key option offers
+ a similar facility (see sshd(8) for details).
Banner The contents of the specified file are sent to the remote user
- before authentication is allowed. If the argument is ``none''
- then no banner is displayed. This option is only available for
+ before authentication is allowed. If the argument is M-bM-^@M-^\noneM-bM-^@M-^] then
+ no banner is displayed. This option is only available for
protocol version 2. By default, no banner is displayed.
ChallengeResponseAuthentication
Specifies whether challenge-response authentication is allowed
- (e.g. via PAM or though authentication styles supported in
- login.conf(5)) The default is ``yes''.
+ (e.g. via PAM or through authentication styles supported in
+ login.conf(5)) The default is M-bM-^@M-^\yesM-bM-^@M-^].
ChrootDirectory
Specifies the pathname of a directory to chroot(2) to after
- authentication. All components of the pathname must be root-
- owned directories that are not writable by any other user or
- group. After the chroot, sshd(8) changes the working directory
- to the user's home directory.
+ authentication. At session startup sshd(8) checks that all
+ components of the pathname are root-owned directories which are
+ not writable by any other user or group. After the chroot,
+ sshd(8) changes the working directory to the user's home
+ directory.
The pathname may contain the following tokens that are expanded
at runtime once the connecting user has been authenticated: %% is
@@ -138,25 +207,48 @@
directories to support the user's session. For an interactive
session this requires at least a shell, typically sh(1), and
basic /dev nodes such as null(4), zero(4), stdin(4), stdout(4),
- stderr(4), arandom(4) and tty(4) devices. For file transfer
- sessions using ``sftp'', no additional configuration of the
- environment is necessary if the in-process sftp server is used,
- though sessions which use logging do require /dev/log inside the
- chroot directory (see sftp-server(8) for details).
+ stderr(4), and tty(4) devices. For file transfer sessions using
+ M-bM-^@M-^\sftpM-bM-^@M-^], no additional configuration of the environment is
+ necessary if the in-process sftp server is used, though sessions
+ which use logging may require /dev/log inside the chroot
+ directory on some operating systems (see sftp-server(8) 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 environments which sshd(8) cannot detect.
The default is not to chroot(2).
Ciphers
Specifies the ciphers allowed for protocol version 2. Multiple
- ciphers must be comma-separated. The supported ciphers are
- ``3des-cbc'', ``aes128-cbc'', ``aes192-cbc'', ``aes256-cbc'',
- ``aes128-ctr'', ``aes192-ctr'', ``aes256-ctr'', ``arcfour128'',
- ``arcfour256'', ``arcfour'', ``blowfish-cbc'', and
- ``cast128-cbc''. The default is:
+ ciphers must be comma-separated. The supported ciphers are:
- aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
- aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
- aes256-cbc,arcfour
+ 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
+
+ The default is:
+
+ aes128-ctr,aes192-ctr,aes256-ctr,
+ aes128-gcm@openssh.com,aes256-gcm@openssh.com,
+ chacha20-poly1305@openssh.com
+
+ The list of available ciphers may also be obtained using the -Q
+ option of ssh(1) with an argument of M-bM-^@M-^\cipherM-bM-^@M-^].
ClientAliveCountMax
Sets the number of client alive messages (see below) which may be
@@ -186,8 +278,8 @@
Compression
Specifies whether compression is allowed, or delayed until the
- user has authenticated successfully. The argument must be
- ``yes'', ``delayed'', or ``no''. The default is ``delayed''.
+ user has authenticated successfully. The argument must be M-bM-^@M-^\yesM-bM-^@M-^],
+ M-bM-^@M-^\delayedM-bM-^@M-^], or M-bM-^@M-^\noM-bM-^@M-^]. The default is M-bM-^@M-^\delayedM-bM-^@M-^].
DenyGroups
This keyword can be followed by a list of group name patterns,
@@ -213,6 +305,10 @@
See PATTERNS in ssh_config(5) for more information on patterns.
+ FingerprintHash
+ Specifies the hash algorithm used when logging key fingerprints.
+ Valid options are: M-bM-^@M-^\md5M-bM-^@M-^] and M-bM-^@M-^\sha256M-bM-^@M-^]. The default is M-bM-^@M-^\sha256M-bM-^@M-^].
+
ForceCommand
Forces the execution of the command specified by ForceCommand,
ignoring any command supplied by the client and ~/.ssh/rc if
@@ -221,7 +317,7 @@
execution. It is most useful inside a Match block. The command
originally supplied by the client is available in the
SSH_ORIGINAL_COMMAND environment variable. Specifying a command
- of ``internal-sftp'' will force the use of an in-process sftp
+ of M-bM-^@M-^\internal-sftpM-bM-^@M-^] will force the use of an in-process sftp
server that requires no support files when used with
ChrootDirectory.
@@ -232,37 +328,43 @@
hosts from connecting to forwarded ports. GatewayPorts can be
used to specify that sshd should allow remote port forwardings to
bind to non-loopback addresses, thus allowing other hosts to
- connect. The argument may be ``no'' to force remote port
- forwardings to be available to the local host only, ``yes'' to
+ connect. The argument may be M-bM-^@M-^\noM-bM-^@M-^] to force remote port
+ forwardings to be available to the local host only, M-bM-^@M-^\yesM-bM-^@M-^] to
force remote port forwardings to bind to the wildcard address, or
- ``clientspecified'' to allow the client to select the address to
- which the forwarding is bound. The default is ``no''.
+ M-bM-^@M-^\clientspecifiedM-bM-^@M-^] to allow the client to select the address to
+ which the forwarding is bound. The default is M-bM-^@M-^\noM-bM-^@M-^].
GSSAPIAuthentication
Specifies whether user authentication based on GSSAPI is allowed.
- The default is ``no''. Note that this option applies to protocol
+ The default is M-bM-^@M-^\noM-bM-^@M-^]. Note that this option applies to protocol
version 2 only.
GSSAPICleanupCredentials
Specifies whether to automatically destroy the user's credentials
- cache on logout. The default is ``yes''. Note that this option
+ cache on logout. The default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that this option
applies to protocol version 2 only.
+ HostbasedAcceptedKeyTypes
+ Specifies the key types that will be accepted for hostbased
+ authentication as a comma-separated pattern list. The default
+ M-bM-^@M-^\*M-bM-^@M-^] will allow all key types. The -Q option of ssh(1) may be
+ used to list supported key types.
+
HostbasedAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication
together with successful public key client host authentication is
allowed (host-based authentication). This option is similar to
RhostsRSAAuthentication and applies to protocol version 2 only.
- The default is ``no''.
+ The default is M-bM-^@M-^\noM-bM-^@M-^].
HostbasedUsesNameFromPacketOnly
Specifies whether or not the server will attempt to perform a
reverse name lookup when matching the name in the ~/.shosts,
~/.rhosts, and /etc/hosts.equiv files during
- HostbasedAuthentication. A setting of ``yes'' means that sshd(8)
+ HostbasedAuthentication. A setting of M-bM-^@M-^\yesM-bM-^@M-^] means that sshd(8)
uses the name supplied by the client rather than attempting to
resolve the name from the TCP connection itself. The default is
- ``no''.
+ M-bM-^@M-^\noM-bM-^@M-^].
HostCertificate
Specifies a file containing a public host certificate. The
@@ -273,67 +375,97 @@
HostKey
Specifies a file containing a private host key used by SSH. The
default is /etc/ssh/ssh_host_key for protocol version 1, and
- /etc/ssh/ssh_host_dsa_key, /etc/ssh/ssh_host_ecdsa_key and
- /etc/ssh/ssh_host_rsa_key for protocol version 2. Note that
- sshd(8) will refuse to use a file if it is group/world-
- accessible. It is possible to have multiple host key files.
- ``rsa1'' keys are used for version 1 and ``dsa'', ``ecdsa'' or
- ``rsa'' are used for version 2 of the SSH protocol.
+ /etc/ssh/ssh_host_dsa_key, /etc/ssh/ssh_host_ecdsa_key,
+ /etc/ssh/ssh_host_ed25519_key and /etc/ssh/ssh_host_rsa_key for
+ protocol version 2. Note that sshd(8) will refuse to use a file
+ if it is group/world-accessible. It is possible to have multiple
+ host key files. M-bM-^@M-^\rsa1M-bM-^@M-^] keys are used for version 1 and M-bM-^@M-^\dsaM-bM-^@M-^],
+ M-bM-^@M-^\ecdsaM-bM-^@M-^], M-bM-^@M-^\ed25519M-bM-^@M-^] or M-bM-^@M-^\rsaM-bM-^@M-^] are used for version 2 of the SSH
+ protocol. It is also possible to specify public host key files
+ instead. In this case operations on the private key will be
+ delegated to an ssh-agent(1).
+
+ HostKeyAgent
+ Identifies the UNIX-domain socket used to communicate with an
+ agent that has access to the private host keys. If
+ M-bM-^@M-^\SSH_AUTH_SOCKM-bM-^@M-^] is specified, the location of the socket will be
+ read from the SSH_AUTH_SOCK environment variable.
IgnoreRhosts
Specifies that .rhosts and .shosts files will not be used in
RhostsRSAAuthentication or HostbasedAuthentication.
/etc/hosts.equiv and /etc/shosts.equiv are still used. The
- default is ``yes''.
+ default is M-bM-^@M-^\yesM-bM-^@M-^].
IgnoreUserKnownHosts
Specifies whether sshd(8) should ignore the user's
~/.ssh/known_hosts during RhostsRSAAuthentication or
- HostbasedAuthentication. The default is ``no''.
+ HostbasedAuthentication. The default is M-bM-^@M-^\noM-bM-^@M-^].
IPQoS Specifies the IPv4 type-of-service or DSCP class for the
- connection. Accepted values are ``af11'', ``af12'', ``af13'',
- ``af14'', ``af22'', ``af23'', ``af31'', ``af32'', ``af33'',
- ``af41'', ``af42'', ``af43'', ``cs0'', ``cs1'', ``cs2'', ``cs3'',
- ``cs4'', ``cs5'', ``cs6'', ``cs7'', ``ef'', ``lowdelay'',
- ``throughput'', ``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 ``lowdelay'' for
- interactive sessions and ``throughput'' for non-interactive
+ connection. Accepted values are M-bM-^@M-^\af11M-bM-^@M-^], M-bM-^@M-^\af12M-bM-^@M-^], M-bM-^@M-^\af13M-bM-^@M-^], M-bM-^@M-^\af21M-bM-^@M-^],
+ M-bM-^@M-^\af22M-bM-^@M-^], M-bM-^@M-^\af23M-bM-^@M-^], M-bM-^@M-^\af31M-bM-^@M-^], M-bM-^@M-^\af32M-bM-^@M-^], M-bM-^@M-^\af33M-bM-^@M-^], M-bM-^@M-^\af41M-bM-^@M-^], M-bM-^@M-^\af42M-bM-^@M-^], M-bM-^@M-^\af43M-bM-^@M-^],
+ M-bM-^@M-^\cs0M-bM-^@M-^], M-bM-^@M-^\cs1M-bM-^@M-^], M-bM-^@M-^\cs2M-bM-^@M-^], M-bM-^@M-^\cs3M-bM-^@M-^], M-bM-^@M-^\cs4M-bM-^@M-^], M-bM-^@M-^\cs5M-bM-^@M-^], M-bM-^@M-^\cs6M-bM-^@M-^], M-bM-^@M-^\cs7M-bM-^@M-^], M-bM-^@M-^\efM-bM-^@M-^],
+ M-bM-^@M-^\lowdelayM-bM-^@M-^], M-bM-^@M-^\throughputM-bM-^@M-^], M-bM-^@M-^\reliabilityM-bM-^@M-^], 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 M-bM-^@M-^\lowdelayM-bM-^@M-^]
+ for interactive sessions and M-bM-^@M-^\throughputM-bM-^@M-^] for non-interactive
sessions.
+ KbdInteractiveAuthentication
+ Specifies whether to allow keyboard-interactive authentication.
+ The argument to this keyword must be M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\noM-bM-^@M-^]. The default
+ is to use whatever value ChallengeResponseAuthentication is set
+ to (by default M-bM-^@M-^\yesM-bM-^@M-^]).
+
KerberosAuthentication
Specifies whether the password provided by the user for
PasswordAuthentication 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 ``no''.
+ is M-bM-^@M-^\noM-bM-^@M-^].
KerberosGetAFSToken
If AFS is active and the user has a Kerberos 5 TGT, attempt to
acquire an AFS token before accessing the user's home directory.
- The default is ``no''.
+ The default is M-bM-^@M-^\noM-bM-^@M-^].
KerberosOrLocalPasswd
If password authentication through Kerberos fails then the
password will be validated via any additional local mechanism
- such as /etc/passwd. The default is ``yes''.
+ such as /etc/passwd. The default is M-bM-^@M-^\yesM-bM-^@M-^].
KerberosTicketCleanup
Specifies whether to automatically destroy the user's ticket
- cache file on logout. The default is ``yes''.
+ cache file on logout. The default is M-bM-^@M-^\yesM-bM-^@M-^].
KexAlgorithms
Specifies the available KEX (Key Exchange) algorithms. Multiple
- algorithms must be comma-separated. The default is
- ``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''.
+ algorithms must be comma-separated. The supported algorithms
+ are:
+
+ curve25519-sha256@libssh.org
+ diffie-hellman-group1-sha1
+ diffie-hellman-group14-sha1
+ diffie-hellman-group-exchange-sha1
+ diffie-hellman-group-exchange-sha256
+ ecdh-sha2-nistp256
+ ecdh-sha2-nistp384
+ ecdh-sha2-nistp521
+
+ The default is:
+
+ curve25519-sha256@libssh.org,
+ ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,
+ diffie-hellman-group-exchange-sha256,
+ diffie-hellman-group14-sha1
+
+ The list of available key exchange algorithms may also be
+ obtained using the -Q option of ssh(1) with an argument of M-bM-^@M-^\kexM-bM-^@M-^].
KeyRegenerationInterval
In protocol version 1, the ephemeral server key is automatically
@@ -373,42 +505,77 @@
MACs Specifies the available MAC (message authentication code)
algorithms. The MAC algorithm is used in protocol version 2 for
data integrity protection. Multiple algorithms must be comma-
- separated. The default is:
+ separated. The algorithms that contain M-bM-^@M-^\-etmM-bM-^@M-^] calculate the MAC
+ after encryption (encrypt-then-mac). These are considered safer
+ and their use recommended. The supported MACs are:
- hmac-md5,hmac-sha1,umac-64@openssh.com,
- hmac-ripemd160,hmac-sha1-96,hmac-md5-96,
- hmac-sha2-256,hmac-sha256-96,hmac-sha2-512,
- hmac-sha2-512-96
+ hmac-md5
+ hmac-md5-96
+ hmac-ripemd160
+ hmac-sha1
+ hmac-sha1-96
+ hmac-sha2-256
+ hmac-sha2-512
+ umac-64@openssh.com
+ umac-128@openssh.com
+ hmac-md5-etm@openssh.com
+ hmac-md5-96-etm@openssh.com
+ hmac-ripemd160-etm@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,
+ umac-64@openssh.com,umac-128@openssh.com,
+ hmac-sha2-256,hmac-sha2-512
+
+ The list of available MAC algorithms may also be obtained using
+ the -Q option of ssh(1) with an argument of M-bM-^@M-^\macM-bM-^@M-^].
Match Introduces a conditional block. If all of the criteria on the
Match line are satisfied, the keywords on the following lines
override those set in the global section of the config file,
- until either another Match line or the end of the file.
+ until either another Match line or the end of the file. If a
+ keyword appears in multiple Match blocks that are satisfied, only
+ the first instance of the keyword is applied.
- The arguments to Match are one or more criteria-pattern pairs.
- The available criteria are User, Group, Host, and Address. The
- match patterns may consist of single entries or comma-separated
- lists and may use the wildcard and negation operators described
- in the PATTERNS section of ssh_config(5).
+ The arguments to Match are one or more criteria-pattern pairs or
+ the single token All which matches all criteria. The available
+ criteria are User, Group, Host, LocalAddress, LocalPort, and
+ Address. The match patterns may consist of single entries or
+ comma-separated lists and may use the wildcard and negation
+ operators described in the PATTERNS section of ssh_config(5).
The patterns in an Address criteria may additionally contain
addresses to match in CIDR address/masklen format, e.g.
- ``192.0.2.0/24'' or ``3ffe:ffff::/32''. 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.
+ M-bM-^@M-^\192.0.2.0/24M-bM-^@M-^] or M-bM-^@M-^\3ffe:ffff::/32M-bM-^@M-^]. 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,
+ M-bM-^@M-^\192.0.2.0/33M-bM-^@M-^] and M-bM-^@M-^\192.0.2.0/8M-bM-^@M-^] respectively.
Only a subset of keywords may be used on the lines following a
- Match keyword. Available keywords are AllowAgentForwarding,
- AllowTcpForwarding, AuthorizedKeysFile, AuthorizedPrincipalsFile,
- Banner, ChrootDirectory, ForceCommand, GatewayPorts,
- GSSAPIAuthentication, HostbasedAuthentication,
- HostbasedUsesNameFromPacketOnly, KbdInteractiveAuthentication,
- KerberosAuthentication, MaxAuthTries, MaxSessions,
- PasswordAuthentication, PermitEmptyPasswords, PermitOpen,
- PermitRootLogin, PermitTunnel, PubkeyAuthentication,
- RhostsRSAAuthentication, RSAAuthentication, X11DisplayOffset,
+ Match keyword. Available keywords are AcceptEnv,
+ AllowAgentForwarding, AllowGroups, AllowStreamLocalForwarding,
+ AllowTcpForwarding, AllowUsers, AuthenticationMethods,
+ AuthorizedKeysCommand, AuthorizedKeysCommandUser,
+ AuthorizedKeysFile, AuthorizedPrincipalsFile, Banner,
+ ChrootDirectory, DenyGroups, DenyUsers, ForceCommand,
+ GatewayPorts, GSSAPIAuthentication, HostbasedAcceptedKeyTypes,
+ HostbasedAuthentication, HostbasedUsesNameFromPacketOnly, IPQoS,
+ KbdInteractiveAuthentication, KerberosAuthentication,
+ MaxAuthTries, MaxSessions, PasswordAuthentication,
+ PermitEmptyPasswords, PermitOpen, PermitRootLogin, PermitTTY,
+ PermitTunnel, PermitUserRC, PubkeyAcceptedKeyTypes,
+ PubkeyAuthentication, RekeyLimit, RevokedKeys,
+ RhostsRSAAuthentication, RSAAuthentication, StreamLocalBindMask,
+ StreamLocalBindUnlink, TrustedUserCAKeys, X11DisplayOffset,
X11Forwarding and X11UseLocalHost.
MaxAuthTries
@@ -424,24 +591,24 @@
Specifies the maximum number of concurrent unauthenticated
connections to the SSH daemon. Additional connections will be
dropped until authentication succeeds or the LoginGraceTime
- expires for a connection. The default is 10.
+ expires for a connection. The default is 10:30:100.
Alternatively, random early drop can be enabled by specifying the
- three colon separated values ``start:rate:full'' (e.g.
- "10:30:60"). sshd(8) 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).
+ three colon separated values M-bM-^@M-^\start:rate:fullM-bM-^@M-^] (e.g. "10:30:60").
+ sshd(8) will refuse connection attempts with a probability of
+ M-bM-^@M-^\rate/100M-bM-^@M-^] (30%) if there are currently M-bM-^@M-^\startM-bM-^@M-^] (10)
+ unauthenticated connections. The probability increases linearly
+ and all connection attempts are refused if the number of
+ unauthenticated connections reaches M-bM-^@M-^\fullM-bM-^@M-^] (60).
PasswordAuthentication
Specifies whether password authentication is allowed. The
- default is ``yes''.
+ default is M-bM-^@M-^\yesM-bM-^@M-^].
PermitEmptyPasswords
When password authentication is allowed, it specifies whether the
server allows login to accounts with empty password strings. The
- default is ``no''.
+ default is M-bM-^@M-^\noM-bM-^@M-^].
PermitOpen
Specifies the destinations to which TCP port forwarding is
@@ -453,38 +620,50 @@
PermitOpen [IPv6_addr]:port
Multiple forwards may be specified by separating them with
- whitespace. An argument of ``any'' can be used to remove all
- restrictions and permit any forwarding requests. By default all
- port forwarding requests are permitted.
+ whitespace. An argument of M-bM-^@M-^\anyM-bM-^@M-^] can be used to remove all
+ restrictions and permit any forwarding requests. An argument of
+ M-bM-^@M-^\noneM-bM-^@M-^] can be used to prohibit all forwarding requests. By
+ default all port forwarding requests are permitted.
PermitRootLogin
Specifies whether root can log in using ssh(1). The argument
- must be ``yes'', ``without-password'', ``forced-commands-only'',
- or ``no''. The default is ``yes''.
+ must be M-bM-^@M-^\yesM-bM-^@M-^], M-bM-^@M-^\without-passwordM-bM-^@M-^], M-bM-^@M-^\forced-commands-onlyM-bM-^@M-^], or
+ M-bM-^@M-^\noM-bM-^@M-^]. The default is M-bM-^@M-^\yesM-bM-^@M-^].
- If this option is set to ``without-password'', password
+ If this option is set to M-bM-^@M-^\without-passwordM-bM-^@M-^], password
authentication is disabled for root.
- If this option is set to ``forced-commands-only'', root login
- with public key authentication will be allowed, but only if the
+ If this option is set to M-bM-^@M-^\forced-commands-onlyM-bM-^@M-^], root login with
+ public key authentication will be allowed, but only if the
command 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 ``no'', root is not allowed to log in.
+ If this option is set to M-bM-^@M-^\noM-bM-^@M-^], root is not allowed to log in.
PermitTunnel
Specifies whether tun(4) device forwarding is allowed. The
- argument must be ``yes'', ``point-to-point'' (layer 3),
- ``ethernet'' (layer 2), or ``no''. Specifying ``yes'' permits
- both ``point-to-point'' and ``ethernet''. The default is ``no''.
+ argument must be M-bM-^@M-^\yesM-bM-^@M-^], M-bM-^@M-^\point-to-pointM-bM-^@M-^] (layer 3), M-bM-^@M-^\ethernetM-bM-^@M-^]
+ (layer 2), or M-bM-^@M-^\noM-bM-^@M-^]. Specifying M-bM-^@M-^\yesM-bM-^@M-^] permits both
+ M-bM-^@M-^\point-to-pointM-bM-^@M-^] and M-bM-^@M-^\ethernetM-bM-^@M-^]. The default is M-bM-^@M-^\noM-bM-^@M-^].
+
+ Independent of this setting, the permissions of the selected
+ tun(4) device must allow access to the user.
+
+ PermitTTY
+ Specifies whether pty(4) allocation is permitted. The default is
+ M-bM-^@M-^\yesM-bM-^@M-^].
PermitUserEnvironment
Specifies whether ~/.ssh/environment and environment= options in
~/.ssh/authorized_keys are processed by sshd(8). The default is
- ``no''. Enabling environment processing may enable users to
- bypass access restrictions in some configurations using
- mechanisms such as LD_PRELOAD.
+ M-bM-^@M-^\noM-bM-^@M-^]. Enabling environment processing may enable users to bypass
+ access restrictions in some configurations using mechanisms such
+ as LD_PRELOAD.
+
+ PermitUserRC
+ Specifies whether any ~/.ssh/rc file is executed. The default is
+ M-bM-^@M-^\yesM-bM-^@M-^].
PidFile
Specifies the file that contains the process ID of the SSH
@@ -497,53 +676,97 @@
PrintLastLog
Specifies whether sshd(8) should print the date and time of the
last user login when a user logs in interactively. The default
- is ``yes''.
+ is M-bM-^@M-^\yesM-bM-^@M-^].
PrintMotd
Specifies whether sshd(8) should print /etc/motd when a user logs
in interactively. (On some systems it is also printed by the
- shell, /etc/profile, or equivalent.) The default is ``yes''.
+ shell, /etc/profile, or equivalent.) The default is M-bM-^@M-^\yesM-bM-^@M-^].
Protocol
Specifies the protocol versions sshd(8) supports. The possible
- values are `1' and `2'. Multiple versions must be comma-
- separated. The default is `2'. Note that the order of the
+ values are M-bM-^@M-^X1M-bM-^@M-^Y and M-bM-^@M-^X2M-bM-^@M-^Y. Multiple versions must be comma-
+ separated. The default is M-bM-^@M-^X2M-bM-^@M-^Y. Note that the order of the
protocol list does not indicate preference, because the client
selects among multiple protocol versions offered by the server.
- Specifying ``2,1'' is identical to ``1,2''.
+ Specifying M-bM-^@M-^\2,1M-bM-^@M-^] is identical to M-bM-^@M-^\1,2M-bM-^@M-^].
+
+ PubkeyAcceptedKeyTypes
+ Specifies the key types that will be accepted for public key
+ authentication as a comma-separated pattern list. The default
+ M-bM-^@M-^\*M-bM-^@M-^] will allow all key types. The -Q option of ssh(1) may be
+ used to list supported key types.
PubkeyAuthentication
Specifies whether public key authentication is allowed. The
- default is ``yes''. Note that this option applies to protocol
+ default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that this option applies to protocol
version 2 only.
+ RekeyLimit
+ Specifies the maximum amount of data that may be transmitted
+ before the 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 M-bM-^@M-^XKM-bM-^@M-^Y, M-bM-^@M-^XMM-bM-^@M-^Y, or M-bM-^@M-^XGM-bM-^@M-^Y to indicate Kilobytes,
+ Megabytes, or Gigabytes, respectively. The default is between
+ M-bM-^@M-^X1GM-bM-^@M-^Y and M-bM-^@M-^X4GM-bM-^@M-^Y, depending on the cipher. The optional second
+ value is specified in seconds and may use any of the units
+ documented in the TIME FORMATS section. The default value for
+ RekeyLimit is M-bM-^@M-^\default noneM-bM-^@M-^], 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. This option
+ applies to protocol version 2 only.
+
RevokedKeys
- Specifies a list of revoked public keys. Keys listed in this
- file will be refused for public key authentication. Note that if
- this file is not readable, then public key authentication will be
- refused for all users.
+ Specifies revoked public keys. Keys listed in this file will be
+ refused for public key authentication. Note that if this file is
+ not readable, 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 generated by ssh-keygen(1). For more information on KRLs, see
+ the KEY REVOCATION LISTS section in ssh-keygen(1).
RhostsRSAAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication
together with successful RSA host authentication is allowed. The
- default is ``no''. This option applies to protocol version 1
- only.
+ default is M-bM-^@M-^\noM-bM-^@M-^]. This option applies to protocol version 1 only.
RSAAuthentication
Specifies whether pure RSA authentication is allowed. The
- default is ``yes''. This option applies to protocol version 1
+ default is M-bM-^@M-^\yesM-bM-^@M-^]. This option applies to protocol version 1
only.
ServerKeyBits
Defines the number of bits in the ephemeral protocol version 1
server key. The minimum value is 512, and the default is 1024.
+ StreamLocalBindMask
+ Sets the octal file creation mode mask (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.
+
+ 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.
+
+ 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 StreamLocalBindUnlink is
+ not enabled, sshd 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 M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\noM-bM-^@M-^]. The default is M-bM-^@M-^\noM-bM-^@M-^].
+
StrictModes
Specifies whether sshd(8) 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
- ``yes''. Note that this does not apply to ChrootDirectory, whose
+ M-bM-^@M-^\yesM-bM-^@M-^]. Note that this does not apply to ChrootDirectory, whose
permissions and ownership are checked unconditionally.
Subsystem
@@ -551,11 +774,11 @@
Arguments should be a subsystem name and a command (with optional
arguments) to execute upon subsystem request.
- The command sftp-server(8) implements the ``sftp'' file transfer
+ The command sftp-server(8) implements the M-bM-^@M-^\sftpM-bM-^@M-^] file transfer
subsystem.
- Alternately the name ``internal-sftp'' implements an in-process
- ``sftp'' server. This may simplify configurations using
+ Alternately the name M-bM-^@M-^\internal-sftpM-bM-^@M-^] implements an in-process
+ M-bM-^@M-^\sftpM-bM-^@M-^] server. This may simplify configurations using
ChrootDirectory to force a different filesystem root on clients.
By default no subsystems are defined. Note that this option
@@ -574,21 +797,21 @@
this means that connections will die if the route is down
temporarily, and some people find it annoying. On the other
hand, if TCP keepalives are not sent, sessions may hang
- indefinitely on the server, leaving ``ghost'' users and consuming
+ indefinitely on the server, leaving M-bM-^@M-^\ghostM-bM-^@M-^] users and consuming
server resources.
- The default is ``yes'' (to send TCP keepalive messages), and the
+ The default is M-bM-^@M-^\yesM-bM-^@M-^] (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
- ``no''.
+ M-bM-^@M-^\noM-bM-^@M-^].
TrustedUserCAKeys
Specifies a file containing public keys of certificate
authorities that are trusted to sign user certificates for
authentication. Keys are listed one per line; empty lines and
- comments starting with `#' are allowed. If a certificate is
+ comments starting with M-bM-^@M-^X#M-bM-^@M-^Y 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
@@ -598,18 +821,18 @@
UseDNS Specifies whether sshd(8) should look up the remote host name and
check that the resolved host name for the remote IP address maps
- back to the very same IP address. The default is ``yes''.
+ back to the very same IP address. The default is M-bM-^@M-^\noM-bM-^@M-^].
UseLogin
Specifies whether login(1) is used for interactive login
- sessions. The default is ``no''. Note that login(1) is never
- used for remote command execution. Note also, that if this is
+ sessions. The default is M-bM-^@M-^\noM-bM-^@M-^]. Note that login(1) is never used
+ for remote command execution. Note also, that if this is
enabled, X11Forwarding will be disabled because login(1) does not
know how to handle xauth(1) cookies. If UsePrivilegeSeparation
is specified, it will be disabled after authentication.
UsePAM Enables the Pluggable Authentication Module interface. If set to
- ``yes'' this will enable PAM authentication using
+ M-bM-^@M-^\yesM-bM-^@M-^] this will enable PAM authentication using
ChallengeResponseAuthentication and PasswordAuthentication in
addition to PAM account and session module processing for all
authentication types.
@@ -619,7 +842,7 @@
either PasswordAuthentication or ChallengeResponseAuthentication.
If UsePAM is enabled, you will not be able to run sshd(8) as a
- non-root user. The default is ``no''.
+ non-root user. The default is M-bM-^@M-^\noM-bM-^@M-^].
UsePrivilegeSeparation
Specifies whether sshd(8) separates privileges by creating an
@@ -628,9 +851,14 @@
that has the privilege of the authenticated user. The goal of
privilege separation is to prevent privilege escalation by
containing any corruption within the unprivileged processes. The
- default is ``yes''. If UsePrivilegeSeparation is set to
- ``sandbox'' then the pre-authentication unprivileged process is
- subject to additional restrictions.
+ default is M-bM-^@M-^\yesM-bM-^@M-^]. If UsePrivilegeSeparation is set to M-bM-^@M-^\sandboxM-bM-^@M-^]
+ then the pre-authentication unprivileged process is subject to
+ additional restrictions.
+
+ VersionAddendum
+ Optionally specifies additional text to append to the SSH
+ protocol banner sent by the server upon connection. The default
+ is M-bM-^@M-^\noneM-bM-^@M-^].
X11DisplayOffset
Specifies the first display number available for sshd(8)'s X11
@@ -639,7 +867,7 @@
X11Forwarding
Specifies whether X11 forwarding is permitted. The argument must
- be ``yes'' or ``no''. The default is ``no''.
+ be M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\noM-bM-^@M-^]. The default is M-bM-^@M-^\noM-bM-^@M-^].
When X11 forwarding is enabled, there may be additional exposure
to the server and to client displays if the sshd(8) proxy display
@@ -653,7 +881,7 @@
ssh_config(5)). A system administrator may have a stance in
which they want to protect clients that may expose themselves to
attack by unwittingly requesting X11 forwarding, which can
- warrant a ``no'' setting.
+ warrant a M-bM-^@M-^\noM-bM-^@M-^] setting.
Note that disabling X11 forwarding does not prevent users from
forwarding X11 traffic, as users can always install their own
@@ -665,12 +893,12 @@
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 DISPLAY environment variable to
- ``localhost''. This prevents remote hosts from connecting to the
+ M-bM-^@M-^\localhostM-bM-^@M-^]. This prevents remote hosts from connecting to the
proxy display. However, some older X11 clients may not function
- with this configuration. X11UseLocalhost may be set to ``no'' to
+ with this configuration. X11UseLocalhost may be set to M-bM-^@M-^\noM-bM-^@M-^] to
specify that the forwarding server should be bound to the
- wildcard address. The argument must be ``yes'' or ``no''. The
- default is ``yes''.
+ wildcard address. The argument must be M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\noM-bM-^@M-^]. The
+ default is M-bM-^@M-^\yesM-bM-^@M-^].
XAuthLocation
Specifies the full pathname of the xauth(1) program. The default
@@ -682,7 +910,7 @@
time[qualifier], where time is a positive integer value and qualifier is
one of the following:
- <none> seconds
+ M-bM-^_M-(noneM-bM-^_M-) seconds
s | S seconds
m | M minutes
h | H hours
@@ -715,4 +943,4 @@
versions 1.5 and 2.0. Niels Provos and Markus Friedl contributed support
for privilege separation.
-OpenBSD 5.0 August 2, 2011 OpenBSD 5.0
+OpenBSD 5.7 February 20, 2015 OpenBSD 5.7