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diff --git a/crypto/openssh/ssh_config.5 b/crypto/openssh/ssh_config.5 deleted file mode 100644 index 20c5893..0000000 --- a/crypto/openssh/ssh_config.5 +++ /dev/null @@ -1,1105 +0,0 @@ -.\" -*- nroff -*- -.\" -.\" Author: Tatu Ylonen <ylo@cs.hut.fi> -.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland -.\" All rights reserved -.\" -.\" As far as I am concerned, the code I have written for this software -.\" can be used freely for any purpose. Any derived versions of this -.\" software must be clearly marked as such, and if the derived work is -.\" incompatible with the protocol description in the RFC file, it must be -.\" called by a name other than "ssh" or "Secure Shell". -.\" -.\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. -.\" Copyright (c) 1999 Aaron Campbell. All rights reserved. -.\" Copyright (c) 1999 Theo de Raadt. All rights reserved. -.\" -.\" Redistribution and use in source and binary forms, with or without -.\" modification, are permitted provided that the following conditions -.\" are met: -.\" 1. Redistributions of source code must retain the above copyright -.\" notice, this list of conditions and the following disclaimer. -.\" 2. Redistributions in binary form must reproduce the above copyright -.\" notice, this list of conditions and the following disclaimer in the -.\" documentation and/or other materials provided with the distribution. -.\" -.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR -.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES -.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. -.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, -.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT -.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, -.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY -.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT -.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF -.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -.\" -.\" $OpenBSD: ssh_config.5,v 1.97 2006/07/27 08:00:50 jmc Exp $ -.Dd September 25, 1999 -.Dt SSH_CONFIG 5 -.Os -.Sh NAME -.Nm ssh_config -.Nd OpenSSH SSH client configuration files -.Sh SYNOPSIS -.Bl -tag -width Ds -compact -.It Pa ~/.ssh/config -.It Pa /etc/ssh/ssh_config -.El -.Sh DESCRIPTION -.Xr ssh 1 -obtains configuration data from the following sources in -the following order: -.Pp -.Bl -enum -offset indent -compact -.It -command-line options -.It -user's configuration file -.Pq Pa ~/.ssh/config -.It -system-wide configuration file -.Pq Pa /etc/ssh/ssh_config -.El -.Pp -For each parameter, the first obtained value -will be used. -The configuration files contain sections separated by -.Dq Host -specifications, and that section is only applied for hosts that -match one of the patterns given in the specification. -The matched host name is the one given on the command line. -.Pp -Since the first obtained value for each parameter is used, more -host-specific declarations should be given near the beginning of the -file, and general defaults at the end. -.Pp -The configuration file has the following format: -.Pp -Empty lines and lines starting with -.Ql # -are comments. -Otherwise a line is of the format -.Dq keyword arguments . -Configuration options may be separated by whitespace or -optional whitespace and exactly one -.Ql = ; -the latter format is useful to avoid the need to quote whitespace -when specifying configuration options using the -.Nm ssh , -.Nm scp , -and -.Nm sftp -.Fl o -option. -Arguments may optionally be enclosed in double quotes -.Pq \&" -in order to represent arguments containing spaces. -.Pp -The possible -keywords and their meanings are as follows (note that -keywords are case-insensitive and arguments are case-sensitive): -.Bl -tag -width Ds -.It Cm Host -Restricts the following declarations (up to the next -.Cm Host -keyword) to be only for those hosts that match one of the patterns -given after the keyword. -A single -.Ql * -as a pattern can be used to provide global -defaults for all hosts. -The host is the -.Ar hostname -argument given on the command line (i.e. the name is not converted to -a canonicalized host name before matching). -.Pp -See -.Sx PATTERNS -for more information on patterns. -.It Cm AddressFamily -Specifies which address family to use when connecting. -Valid arguments are -.Dq any , -.Dq inet -(use IPv4 only), or -.Dq inet6 -(use IPv6 only). -.It Cm BatchMode -If set to -.Dq yes , -passphrase/password querying will be disabled. -This option is useful in scripts and other batch jobs where no user -is present to supply the password. -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -.It Cm BindAddress -Use the specified address on the local machine as the source address of -the connection. -Only useful on systems with more than one address. -Note that this option does not work if -.Cm UsePrivilegedPort -is set to -.Dq yes . -.It Cm ChallengeResponseAuthentication -Specifies whether to use challenge-response authentication. -The argument to this keyword must be -.Dq yes -or -.Dq no . -The default is -.Dq yes . -.It Cm CheckHostIP -If this flag is set to -.Dq yes , -.Xr ssh 1 -will additionally check the host IP address in the -.Pa known_hosts -file. -This allows ssh to detect if a host key changed due to DNS spoofing. -If the option is set to -.Dq no , -the check will not be executed. -The default is -.Dq yes . -.It Cm Cipher -Specifies the cipher to use for encrypting the session -in protocol version 1. -Currently, -.Dq blowfish , -.Dq 3des , -and -.Dq des -are supported. -.Ar des -is only supported in the -.Xr ssh 1 -client for interoperability with legacy protocol 1 implementations -that do not support the -.Ar 3des -cipher. -Its use is strongly discouraged due to cryptographic weaknesses. -The default is -.Dq 3des . -.It Cm Ciphers -Specifies the ciphers allowed for protocol version 2 -in order of preference. -Multiple ciphers must be comma-separated. -The supported ciphers are -.Dq 3des-cbc , -.Dq aes128-cbc , -.Dq aes192-cbc , -.Dq aes256-cbc , -.Dq aes128-ctr , -.Dq aes192-ctr , -.Dq aes256-ctr , -.Dq arcfour128 , -.Dq arcfour256 , -.Dq arcfour , -.Dq blowfish-cbc , -and -.Dq cast128-cbc . -The default is: -.Bd -literal -offset 3n -aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128, -arcfour256,arcfour,aes192-cbc,aes256-cbc,aes128-ctr, -aes192-ctr,aes256-ctr -.Ed -.It Cm ClearAllForwardings -Specifies that all local, remote, and dynamic port forwardings -specified in the configuration files or on the command line be -cleared. -This option is primarily useful when used from the -.Xr ssh 1 -command line to clear port forwardings set in -configuration files, and is automatically set by -.Xr scp 1 -and -.Xr sftp 1 . -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -.It Cm Compression -Specifies whether to use compression. -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -.It Cm CompressionLevel -Specifies the compression level to use if compression is enabled. -The argument must be an integer from 1 (fast) to 9 (slow, best). -The default level is 6, which is good for most applications. -The meaning of the values is the same as in -.Xr gzip 1 . -Note that this option applies to protocol version 1 only. -.It Cm ConnectionAttempts -Specifies the number of tries (one per second) to make before exiting. -The argument must be an integer. -This may be useful in scripts if the connection sometimes fails. -The default is 1. -.It Cm ConnectTimeout -Specifies the timeout (in seconds) used when connecting to the -SSH server, instead of using the default system TCP timeout. -This value is used only when the target is down or really unreachable, -not when it refuses the connection. -.It Cm ControlMaster -Enables the sharing of multiple sessions over a single network connection. -When set to -.Dq yes , -.Xr ssh 1 -will listen for connections on a control socket specified using the -.Cm ControlPath -argument. -Additional sessions can connect to this socket using the same -.Cm ControlPath -with -.Cm ControlMaster -set to -.Dq no -(the default). -These sessions will try to reuse the master instance's network connection -rather than initiating new ones, but will fall back to connecting normally -if the control socket does not exist, or is not listening. -.Pp -Setting this to -.Dq ask -will cause ssh -to listen for control connections, but require confirmation using the -.Ev SSH_ASKPASS -program before they are accepted (see -.Xr ssh-add 1 -for details). -If the -.Cm ControlPath -cannot be opened, -ssh will continue without connecting to a master instance. -.Pp -X11 and -.Xr ssh-agent 1 -forwarding is supported over these multiplexed connections, however the -display and agent forwarded will be the one belonging to the master -connection i.e. it is not possible to forward multiple displays or agents. -.Pp -Two additional options allow for opportunistic multiplexing: try to use a -master connection but fall back to creating a new one if one does not already -exist. -These options are: -.Dq auto -and -.Dq autoask . -The latter requires confirmation like the -.Dq ask -option. -.It Cm ControlPath -Specify the path to the control socket used for connection sharing as described -in the -.Cm ControlMaster -section above or the string -.Dq none -to disable connection sharing. -In the path, -.Ql %l -will be substituted by the local host name, -.Ql %h -will be substituted by the target host name, -.Ql %p -the port, and -.Ql %r -by the remote login username. -It is recommended that any -.Cm ControlPath -used for opportunistic connection sharing include -at least %h, %p, and %r. -This ensures that shared connections are uniquely identified. -.It Cm DynamicForward -Specifies that a TCP port on the local machine be forwarded -over the secure channel, and the application -protocol is then used to determine where to connect to from the -remote machine. -.Pp -The argument must be -.Sm off -.Oo Ar bind_address : Oc Ar port . -.Sm on -IPv6 addresses can be specified by enclosing addresses in square brackets or -by using an alternative syntax: -.Oo Ar bind_address Ns / Oc Ns Ar port . -By default, the local port is bound in accordance with the -.Cm GatewayPorts -setting. -However, an explicit -.Ar bind_address -may be used to bind the connection to a specific address. -The -.Ar bind_address -of -.Dq localhost -indicates that the listening port be bound for local use only, while an -empty address or -.Sq * -indicates that the port should be available from all interfaces. -.Pp -Currently the SOCKS4 and SOCKS5 protocols are supported, and -.Xr ssh 1 -will act as a SOCKS server. -Multiple forwardings may be specified, and -additional forwardings can be given on the command line. -Only the superuser can forward privileged ports. -.It Cm EnableSSHKeysign -Setting this option to -.Dq yes -in the global client configuration file -.Pa /etc/ssh/ssh_config -enables the use of the helper program -.Xr ssh-keysign 8 -during -.Cm HostbasedAuthentication . -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -This option should be placed in the non-hostspecific section. -See -.Xr ssh-keysign 8 -for more information. -.It Cm EscapeChar -Sets the escape character (default: -.Ql ~ ) . -The escape character can also -be set on the command line. -The argument should be a single character, -.Ql ^ -followed by a letter, or -.Dq none -to disable the escape -character entirely (making the connection transparent for binary -data). -.It Cm ExitOnForwardFailure -Specifies whether -.Xr ssh 1 -should terminate the connection if it cannot set up all requested -dynamic, local, and remote port forwardings. -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -.It Cm ForwardAgent -Specifies whether the connection to the authentication agent (if any) -will be forwarded to the remote machine. -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -.Pp -Agent forwarding should be enabled with caution. -Users with the ability to bypass file permissions on the remote host -(for the agent's Unix-domain socket) -can access the local agent through the forwarded connection. -An attacker cannot obtain key material from the agent, -however they can perform operations on the keys that enable them to -authenticate using the identities loaded into the agent. -.It Cm ForwardX11 -Specifies whether X11 connections will be automatically redirected -over the secure channel and -.Ev DISPLAY -set. -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -.Pp -X11 forwarding should be enabled with caution. -Users with the ability to bypass file permissions on the remote host -(for the user's X11 authorization database) -can access the local X11 display through the forwarded connection. -An attacker may then be able to perform activities such as keystroke monitoring -if the -.Cm ForwardX11Trusted -option is also enabled. -.It Cm ForwardX11Trusted -If this option is set to -.Dq yes , -remote X11 clients will have full access to the original X11 display. -.Pp -If this option is set to -.Dq no , -remote X11 clients will be considered untrusted and prevented -from stealing or tampering with data belonging to trusted X11 -clients. -Furthermore, the -.Xr xauth 1 -token used for the session will be set to expire after 20 minutes. -Remote clients will be refused access after this time. -.Pp -The default is -.Dq no . -.Pp -See the X11 SECURITY extension specification for full details on -the restrictions imposed on untrusted clients. -.It Cm GatewayPorts -Specifies whether remote hosts are allowed to connect to local -forwarded ports. -By default, -.Xr ssh 1 -binds local port forwardings to the loopback address. -This prevents other remote hosts from connecting to forwarded ports. -.Cm GatewayPorts -can be used to specify that ssh -should bind local port forwardings to the wildcard address, -thus allowing remote hosts to connect to forwarded ports. -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -.It Cm GlobalKnownHostsFile -Specifies a file to use for the global -host key database instead of -.Pa /etc/ssh/ssh_known_hosts . -.It Cm GSSAPIAuthentication -Specifies whether user authentication based on GSSAPI is allowed. -The default is -.Dq no . -Note that this option applies to protocol version 2 only. -.It Cm GSSAPIDelegateCredentials -Forward (delegate) credentials to the server. -The default is -.Dq no . -Note that this option applies to protocol version 2 only. -.It Cm HashKnownHosts -Indicates that -.Xr ssh 1 -should hash host names and addresses when they are added to -.Pa ~/.ssh/known_hosts . -These hashed names may be used normally by -.Xr ssh 1 -and -.Xr sshd 8 , -but they do not reveal identifying information should the file's contents -be disclosed. -The default is -.Dq no . -Note that existing names and addresses in known hosts files -will not be converted automatically, -but may be manually hashed using -.Xr ssh-keygen 1 . -.It Cm HostbasedAuthentication -Specifies whether to try rhosts based authentication with public key -authentication. -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -This option applies to protocol version 2 only and -is similar to -.Cm RhostsRSAAuthentication . -.It Cm HostKeyAlgorithms -Specifies the protocol version 2 host key algorithms -that the client wants to use in order of preference. -The default for this option is: -.Dq ssh-rsa,ssh-dss . -.It Cm HostKeyAlias -Specifies an alias that should be used instead of the -real host name when looking up or saving the host key -in the host key database files. -This option is useful for tunneling SSH connections -or for multiple servers running on a single host. -.It Cm HostName -Specifies the real host name to log into. -This can be used to specify nicknames or abbreviations for hosts. -The default is the name given on the command line. -Numeric IP addresses are also permitted (both on the command line and in -.Cm HostName -specifications). -.It Cm IdentitiesOnly -Specifies that -.Xr ssh 1 -should only use the authentication identity files configured in the -.Nm -files, -even if -.Xr ssh-agent 1 -offers more identities. -The argument to this keyword must be -.Dq yes -or -.Dq no . -This option is intended for situations where ssh-agent -offers many different identities. -The default is -.Dq no . -.It Cm IdentityFile -Specifies a file from which the user's RSA or DSA authentication identity -is read. -The default is -.Pa ~/.ssh/identity -for protocol version 1, and -.Pa ~/.ssh/id_rsa -and -.Pa ~/.ssh/id_dsa -for protocol version 2. -Additionally, any identities represented by the authentication agent -will be used for authentication. -.Pp -The file name may use the tilde -syntax to refer to a user's home directory or one of the following -escape characters: -.Ql %d -(local user's home directory), -.Ql %u -(local user name), -.Ql %l -(local host name), -.Ql %h -(remote host name) or -.Ql %r -(remote user name). -.Pp -It is possible to have -multiple identity files specified in configuration files; all these -identities will be tried in sequence. -.It Cm KbdInteractiveDevices -Specifies the list of methods to use in keyboard-interactive authentication. -Multiple method names must be comma-separated. -The default is to use the server specified list. -The methods available vary depending on what the server supports. -For an OpenSSH server, -it may be zero or more of: -.Dq bsdauth , -.Dq pam , -and -.Dq skey . -.It Cm LocalCommand -Specifies a command to execute on the local machine after successfully -connecting to the server. -The command string extends to the end of the line, and is executed with -.Pa /bin/sh . -This directive is ignored unless -.Cm PermitLocalCommand -has been enabled. -.It Cm LocalForward -Specifies that a TCP port on the local machine be forwarded over -the secure channel to the specified host and port from the remote machine. -The first argument must be -.Sm off -.Oo Ar bind_address : Oc Ar port -.Sm on -and the second argument must be -.Ar host : Ns Ar hostport . -IPv6 addresses can be specified by enclosing addresses in square brackets or -by using an alternative syntax: -.Oo Ar bind_address Ns / Oc Ns Ar port -and -.Ar host Ns / Ns Ar hostport . -Multiple forwardings may be specified, and additional forwardings can be -given on the command line. -Only the superuser can forward privileged ports. -By default, the local port is bound in accordance with the -.Cm GatewayPorts -setting. -However, an explicit -.Ar bind_address -may be used to bind the connection to a specific address. -The -.Ar bind_address -of -.Dq localhost -indicates that the listening port be bound for local use only, while an -empty address or -.Sq * -indicates that the port should be available from all interfaces. -.It Cm LogLevel -Gives the verbosity level that is used when logging messages from -.Xr ssh 1 . -The possible values are: -QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. -The default is INFO. -DEBUG and DEBUG1 are equivalent. -DEBUG2 and DEBUG3 each specify higher levels of verbose output. -.It Cm MACs -Specifies the MAC (message authentication code) algorithms -in order of preference. -The MAC algorithm is used in protocol version 2 -for data integrity protection. -Multiple algorithms must be comma-separated. -The default is: -.Dq hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96 . -.It Cm NoHostAuthenticationForLocalhost -This option can be used if the home directory is shared across machines. -In this case localhost will refer to a different machine on each of -the machines and the user will get many warnings about changed host keys. -However, this option disables host authentication for localhost. -The argument to this keyword must be -.Dq yes -or -.Dq no . -The default is to check the host key for localhost. -.It Cm NumberOfPasswordPrompts -Specifies the number of password prompts before giving up. -The argument to this keyword must be an integer. -The default is 3. -.It Cm PasswordAuthentication -Specifies whether to use password authentication. -The argument to this keyword must be -.Dq yes -or -.Dq no . -The default is -.Dq yes . -.It Cm PermitLocalCommand -Allow local command execution via the -.Ic LocalCommand -option or using the -.Ic !\& Ns Ar command -escape sequence in -.Xr ssh 1 . -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -.It Cm Port -Specifies the port number to connect on the remote host. -The default is 22. -.It Cm PreferredAuthentications -Specifies the order in which the client should try protocol 2 -authentication methods. -This allows a client to prefer one method (e.g.\& -.Cm keyboard-interactive ) -over another method (e.g.\& -.Cm password ) -The default for this option is: -.Do gssapi-with-mic , -hostbased, -publickey, -keyboard-interactive, -password -.Dc . -.It Cm Protocol -Specifies the protocol versions -.Xr ssh 1 -should support in order of preference. -The possible values are -.Sq 1 -and -.Sq 2 . -Multiple versions must be comma-separated. -The default is -.Dq 2,1 . -This means that ssh -tries version 2 and falls back to version 1 -if version 2 is not available. -.It Cm ProxyCommand -Specifies the command to use to connect to the server. -The command -string extends to the end of the line, and is executed with -.Pa /bin/sh . -In the command string, -.Ql %h -will be substituted by the host name to -connect and -.Ql %p -by the port. -The command can be basically anything, -and should read from its standard input and write to its standard output. -It should eventually connect an -.Xr sshd 8 -server running on some machine, or execute -.Ic sshd -i -somewhere. -Host key management will be done using the -HostName of the host being connected (defaulting to the name typed by -the user). -Setting the command to -.Dq none -disables this option entirely. -Note that -.Cm CheckHostIP -is not available for connects with a proxy command. -.Pp -This directive is useful in conjunction with -.Xr nc 1 -and its proxy support. -For example, the following directive would connect via an HTTP proxy at -192.0.2.0: -.Bd -literal -offset 3n -ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p -.Ed -.It Cm PubkeyAuthentication -Specifies whether to try public key authentication. -The argument to this keyword must be -.Dq yes -or -.Dq no . -The default is -.Dq yes . -This option applies to protocol version 2 only. -.It Cm RekeyLimit -Specifies the maximum amount of data that may be transmitted before the -session key is renegotiated. -The argument is the number of bytes, with an optional suffix of -.Sq K , -.Sq M , -or -.Sq G -to indicate Kilobytes, Megabytes, or Gigabytes, respectively. -The default is between -.Sq 1G -and -.Sq 4G , -depending on the cipher. -This option applies to protocol version 2 only. -.It Cm RemoteForward -Specifies that a TCP port on the remote machine be forwarded over -the secure channel to the specified host and port from the local machine. -The first argument must be -.Sm off -.Oo Ar bind_address : Oc Ar port -.Sm on -and the second argument must be -.Ar host : Ns Ar hostport . -IPv6 addresses can be specified by enclosing addresses in square brackets -or by using an alternative syntax: -.Oo Ar bind_address Ns / Oc Ns Ar port -and -.Ar host Ns / Ns Ar hostport . -Multiple forwardings may be specified, and additional -forwardings can be given on the command line. -Only the superuser can forward privileged ports. -.Pp -If the -.Ar bind_address -is not specified, the default is to only bind to loopback addresses. -If the -.Ar bind_address -is -.Ql * -or an empty string, then the forwarding is requested to listen on all -interfaces. -Specifying a remote -.Ar bind_address -will only succeed if the server's -.Cm GatewayPorts -option is enabled (see -.Xr sshd_config 5 ) . -.It Cm RhostsRSAAuthentication -Specifies whether to try rhosts based authentication with RSA host -authentication. -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -This option applies to protocol version 1 only and requires -.Xr ssh 1 -to be setuid root. -.It Cm RSAAuthentication -Specifies whether to try RSA authentication. -The argument to this keyword must be -.Dq yes -or -.Dq no . -RSA authentication will only be -attempted if the identity file exists, or an authentication agent is -running. -The default is -.Dq yes . -Note that this option applies to protocol version 1 only. -.It Cm SendEnv -Specifies what variables from the local -.Xr environ 7 -should be sent to the server. -Note that environment passing is only supported for protocol 2. -The server must also support it, and the server must be configured to -accept these environment variables. -Refer to -.Cm AcceptEnv -in -.Xr sshd_config 5 -for how to configure the server. -Variables are specified by name, which may contain wildcard characters. -Multiple environment variables may be separated by whitespace or spread -across multiple -.Cm SendEnv -directives. -The default is not to send any environment variables. -.Pp -See -.Sx PATTERNS -for more information on patterns. -.It Cm ServerAliveCountMax -Sets the number of server alive messages (see below) which may be -sent without -.Xr ssh 1 -receiving any messages back from the server. -If this threshold is reached while server alive messages are being sent, -ssh will disconnect from the server, terminating the session. -It is important to note that the use of server alive messages is very -different from -.Cm TCPKeepAlive -(below). -The server alive messages are sent through the encrypted channel -and therefore will not be spoofable. -The TCP keepalive option enabled by -.Cm TCPKeepAlive -is spoofable. -The server alive mechanism is valuable when the client or -server depend on knowing when a connection has become inactive. -.Pp -The default value is 3. -If, for example, -.Cm ServerAliveInterval -(see below) is set to 15 and -.Cm ServerAliveCountMax -is left at the default, if the server becomes unresponsive, -ssh will disconnect after approximately 45 seconds. -This option applies to protocol version 2 only. -.It Cm ServerAliveInterval -Sets a timeout interval in seconds after which if no data has been received -from the server, -.Xr ssh 1 -will send a message through the encrypted -channel to request a response from the server. -The default -is 0, indicating that these messages will not be sent to the server. -This option applies to protocol version 2 only. -.It Cm SmartcardDevice -Specifies which smartcard device to use. -The argument to this keyword is the device -.Xr ssh 1 -should use to communicate with a smartcard used for storing the user's -private RSA key. -By default, no device is specified and smartcard support is not activated. -.It Cm StrictHostKeyChecking -If this flag is set to -.Dq yes , -.Xr ssh 1 -will never automatically add host keys to the -.Pa ~/.ssh/known_hosts -file, and refuses to connect to hosts whose host key has changed. -This provides maximum protection against trojan horse attacks, -though it can be annoying when the -.Pa /etc/ssh/ssh_known_hosts -file is poorly maintained or when connections to new hosts are -frequently made. -This option forces the user to manually -add all new hosts. -If this flag is set to -.Dq no , -ssh will automatically add new host keys to the -user known hosts files. -If this flag is set to -.Dq ask , -new host keys -will be added to the user known host files only after the user -has confirmed that is what they really want to do, and -ssh will refuse to connect to hosts whose host key has changed. -The host keys of -known hosts will be verified automatically in all cases. -The argument must be -.Dq yes , -.Dq no , -or -.Dq ask . -The default is -.Dq ask . -.It Cm TCPKeepAlive -Specifies whether the system should send TCP keepalive messages to the -other side. -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 temporarily, and some people -find it annoying. -.Pp -The default is -.Dq yes -(to send TCP keepalive messages), and the client will notice -if the network goes down or the remote host dies. -This is important in scripts, and many users want it too. -.Pp -To disable TCP keepalive messages, the value should be set to -.Dq no . -.It Cm Tunnel -Request -.Xr tun 4 -device forwarding between the client and the server. -The argument must be -.Dq yes , -.Dq point-to-point -(layer 3), -.Dq ethernet -(layer 2), -or -.Dq no . -Specifying -.Dq yes -requests the default tunnel mode, which is -.Dq point-to-point . -The default is -.Dq no . -.It Cm TunnelDevice -Specifies the -.Xr tun 4 -devices to open on the client -.Pq Ar local_tun -and the server -.Pq Ar remote_tun . -.Pp -The argument must be -.Sm off -.Ar local_tun Op : Ar remote_tun . -.Sm on -The devices may be specified by numerical ID or the keyword -.Dq any , -which uses the next available tunnel device. -If -.Ar remote_tun -is not specified, it defaults to -.Dq any . -The default is -.Dq any:any . -.It Cm UsePrivilegedPort -Specifies whether to use a privileged port for outgoing connections. -The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -If set to -.Dq yes , -.Xr ssh 1 -must be setuid root. -Note that this option must be set to -.Dq yes -for -.Cm RhostsRSAAuthentication -with older servers. -.It Cm User -Specifies the user to log in as. -This can be useful when a different user name is used on different machines. -This saves the trouble of -having to remember to give the user name on the command line. -.It Cm UserKnownHostsFile -Specifies a file to use for the user -host key database instead of -.Pa ~/.ssh/known_hosts . -.It Cm VerifyHostKeyDNS -Specifies whether to verify the remote key using DNS and SSHFP resource -records. -If this option is set to -.Dq yes , -the client will implicitly trust keys that match a secure fingerprint -from DNS. -Insecure fingerprints will be handled as if this option was set to -.Dq ask . -If this option is set to -.Dq ask , -information on fingerprint match will be displayed, but the user will still -need to confirm new host keys according to the -.Cm StrictHostKeyChecking -option. -The argument must be -.Dq yes , -.Dq no , -or -.Dq ask . -The default is -.Dq no . -Note that this option applies to protocol version 2 only. -.Pp -See also -.Sx VERIFYING HOST KEYS -in -.Xr ssh 1 . -.It Cm XAuthLocation -Specifies the full pathname of the -.Xr xauth 1 -program. -The default is -.Pa /usr/X11R6/bin/xauth . -.El -.Sh PATTERNS -A -.Em pattern -consists of zero or more non-whitespace characters, -.Sq * -(a wildcard that matches zero or more characters), -or -.Sq ?\& -(a wildcard that matches exactly one character). -For example, to specify a set of declarations for any host in the -.Dq .co.uk -set of domains, -the following pattern could be used: -.Pp -.Dl Host *.co.uk -.Pp -The following pattern -would match any host in the 192.168.0.[0-9] network range: -.Pp -.Dl Host 192.168.0.? -.Pp -A -.Em pattern-list -is a comma-separated list of patterns. -Patterns within pattern-lists may be negated -by preceding them with an exclamation mark -.Pq Sq !\& . -For example, -to allow a key to be used from anywhere within an organisation -except from the -.Dq dialup -pool, -the following entry (in authorized_keys) could be used: -.Pp -.Dl from=\&"!*.dialup.example.com,*.example.com\&" -.Sh FILES -.Bl -tag -width Ds -.It Pa ~/.ssh/config -This is the per-user configuration file. -The format of this file is described above. -This file is used by the SSH client. -Because of the potential for abuse, this file must have strict permissions: -read/write for the user, and not accessible by others. -.It Pa /etc/ssh/ssh_config -Systemwide configuration file. -This file provides defaults for those -values that are not specified in the user's configuration file, and -for those users who do not have a configuration file. -This file must be world-readable. -.El -.Sh SEE ALSO -.Xr ssh 1 -.Sh AUTHORS -OpenSSH is a derivative of the original and free -ssh 1.2.12 release by Tatu Ylonen. -Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, -Theo de Raadt and Dug Song -removed many bugs, re-added newer features and -created OpenSSH. -Markus Friedl contributed the support for SSH -protocol versions 1.5 and 2.0. |
