===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/ssh.1,v
retrieving revision 1.150
retrieving revision 1.150.2.5
diff -u -r1.150 -r1.150.2.5
--- src/usr.bin/ssh/ssh.1	2002/03/26 11:34:49	1.150
+++ src/usr.bin/ssh/ssh.1	2003/04/03 22:35:18	1.150.2.5
@@ -34,7 +34,7 @@
 .\" (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.1,v 1.150 2002/03/26 11:34:49 markus Exp $
+.\" $OpenBSD: ssh.1,v 1.150.2.5 2003/04/03 22:35:18 miod Exp $
 .Dd September 25, 1999
 .Dt SSH 1
 .Os
@@ -48,7 +48,8 @@
 .Op Ar command
 .Pp
 .Nm ssh
-.Op Fl afgknqstvxACNPTX1246
+.Bk -words
+.Op Fl afgknqstvxACNTX1246
 .Op Fl b Ar bind_address
 .Op Fl c Ar cipher_spec
 .Op Fl e Ar escape_char
@@ -66,6 +67,8 @@
 .Sm on
 .Xc
 .Oc
+.Ek
+.Bk -words
 .Oo Fl R Xo
 .Sm off
 .Ar port :
@@ -77,6 +80,7 @@
 .Op Fl D Ar port
 .Ar hostname | user@hostname
 .Op Ar command
+.Ek
 .Sh DESCRIPTION
 .Nm
 (SSH client) is a program for logging into a remote machine and for
@@ -353,9 +357,17 @@
 The real authentication cookie is never
 sent to the server machine (and no cookies are sent in the plain).
 .Pp
-If the user is using an authentication agent, the connection to the agent
-is automatically forwarded to the remote side unless disabled on
-the command line or in a configuration file.
+If the
+.Cm ForwardAgent
+variable is set to
+.Dq yes
+(or, see the description of the
+.Fl A
+and
+.Fl a
+options described later) and
+the user is using an authentication agent, the connection to the agent
+is automatically forwarded to the remote side.
 .Pp
 Forwarding of arbitrary TCP/IP connections over the secure channel can
 be specified either on the command line or in a configuration file.
@@ -384,7 +396,7 @@
 otherwise be used to circumvent the encryption.
 The
 .Cm StrictHostKeyChecking
-option (see below) can be used to prevent logins to machines whose
+option can be used to prevent logins to machines whose
 host key is not known or has changed.
 .Pp
 The options are as follows:
@@ -394,6 +406,14 @@
 .It Fl A
 Enables forwarding of the authentication agent connection.
 This can also be specified on a per-host basis in a configuration file.
+.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 Fl b Ar bind_address
 Specify the interface to transmit from on machines with multiple
 interfaces or aliased addresses.
@@ -413,8 +433,8 @@
 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.
+cipher.
+Its use is strongly discouraged due to cryptographic weaknesses.
 .It Fl c Ar cipher_spec
 Additionally, for protocol version 2 a comma-separated list of ciphers can
 be specified in order of preference.
@@ -515,15 +535,6 @@
 Port to connect to on the remote host.
 This can be specified on a
 per-host basis in the configuration file.
-.It Fl P
-Use a non-privileged port for outgoing connections.
-This can be used if a firewall does
-not permit connections from privileged ports.
-Note that this option turns off
-.Cm RhostsAuthentication
-and
-.Cm RhostsRSAAuthentication
-for older servers.
 .It Fl q
 Quiet mode.
 Causes all warning and diagnostic messages to be suppressed.
@@ -559,6 +570,12 @@
 .It Fl X
 Enables X11 forwarding.
 This can also be specified on a per-host basis in a configuration file.
+.Pp
+X11 forwarding should be enabled with caution.
+Users with the ability to bypass file permissions on the remote host
+(for the user's X 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.
 .It Fl C
 Requests compression of all data (including stdin, stdout, stderr, and
 data for forwarded X11 and TCP/IP connections).
@@ -568,13 +585,13 @@
 .Dq level
 can be controlled by the
 .Cm CompressionLevel
-option (see below).
+option for protocol version 1.
 Compression is desirable on modem lines and other
 slow connections, but will only slow down things on fast networks.
 The default value can be set on a host-by-host basis in the
 configuration files; see the
 .Cm Compression
-option below.
+option.
 .It Fl F Ar configfile
 Specifies an alternative per-user configuration file.
 If a configuration file is given on the command line,
@@ -625,7 +642,8 @@
 on the local side, and whenever a connection is made to this port, the
 connection is forwarded over the secure channel, and the application
 protocol is then used to determine where to connect to from the
-remote machine.  Currently the SOCKS4 protocol is supported, and
+remote machine.
+Currently the SOCKS4 protocol is supported, and
 .Nm
 will act as a SOCKS4 server.
 Only root can forward privileged ports.
@@ -649,580 +667,10 @@
 .El
 .Sh CONFIGURATION FILES
 .Nm
-obtains configuration data from the following sources in
-the following order:
-command line options, user's configuration file
-.Pq Pa $HOME/.ssh/config ,
-and system-wide configuration file
-.Pq Pa /etc/ssh/ssh_config .
-For each parameter, the first obtained value
-will be used.
-The configuration files contain sections bracketed 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.
-.Pp
-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.
-.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.
-.Ql \&*
-and
-.Ql ?
-can be used as wildcards in the
-patterns.
-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).
-.It Cm AFSTokenPassing
-Specifies whether to pass AFS tokens to remote host.
-The argument to this keyword must be
-.Dq yes
-or
-.Dq no .
-This option applies to protocol version 1 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
-Specify the interface to transmit from on machines with multiple
-interfaces or aliased addresses.
-Note that this option does not work if
-.Cm UsePrivilegedPort
-is set to
-.Dq yes .
-.It Cm CheckHostIP
-If this flag is set to
-.Dq yes ,
-ssh 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
-.Nm
-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 default is
-.Pp
-.Bd -literal
-  ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,
-    aes192-cbc,aes256-cbc''
-.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
-.Nm
-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 falling
-back to rsh or exiting.
-The argument must be an integer.
-This may be useful in scripts if the connection sometimes fails.
-The default is 1.
-.It Cm DynamicForward
-Specifies that a TCP/IP 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.  The argument must be a port number.
-Currently the SOCKS4 protocol is supported, and
-.Nm
-will act as a SOCKS4 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 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 FallBackToRsh
-Specifies that if connecting via
-.Nm
-fails due to a connection refused error (there is no
-.Xr sshd 8
-listening on the remote host),
-.Xr rsh 1
-should automatically be used instead (after a suitable warning about
-the session being unencrypted).
-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 .
-.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 .
-.It Cm GatewayPorts
-Specifies whether remote hosts are allowed to connect to local
-forwarded ports.
-By default,
-.Nm
-binds local port forwardings to the loopback addresss.  This
-prevents other remote hosts from connecting to forwarded ports.
-.Cm GatewayPorts
-can be used to specify that
-.Nm
-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 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.
-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 IdentityFile
-Specifies a file from which the user's RSA or DSA authentication identity
-is read. The default is
-.Pa $HOME/.ssh/identity
-for protocol version 1, and
-.Pa $HOME/.ssh/id_rsa
-and
-.Pa $HOME/.ssh/id_dsa
-for protocol version 2.
-Additionally, any identities represented by the authentication agent
-will be used for authentication.
-The file name may use the tilde
-syntax to refer to a user's home directory.
-It is possible to have
-multiple identity files specified in configuration files; all these
-identities will be tried in sequence.
-.It Cm KeepAlive
-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 keepalives), 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 keepalives, the value should be set to
-.Dq no .
-.It Cm KerberosAuthentication
-Specifies whether Kerberos authentication will be used.
-The argument to this keyword must be
-.Dq yes
-or
-.Dq no .
-.It Cm KerberosTgtPassing
-Specifies whether a Kerberos TGT will be forwarded to the server.
-This will only work if the Kerberos server is actually an AFS kaserver.
-The argument to this keyword must be
-.Dq yes
-or
-.Dq no .
-.It Cm LocalForward
-Specifies that a TCP/IP 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 a port number, and the second must be
-.Ar host:port .
-IPv6 addresses can be specified with an alternative syntax:
-.Ar host/port .
-Multiple forwardings may be specified, and additional
-forwardings can be given on the command line.
-Only the superuser can forward privileged ports.
-.It Cm LogLevel
-Gives the verbosity level that is used when logging messages from
-.Nm ssh .
-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.
-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 Port
-Specifies the port number to connect on the remote host.
-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:
-.Dq hostbased,publickey,keyboard-interactive,password .
-.It Cm Protocol
-Specifies the protocol versions
-.Nm
-should support in order of preference.
-The possible values are
-.Dq 1
-and
-.Dq 2 .
-Multiple versions must be comma-separated.
-The default is
-.Dq 2,1 .
-This means that
-.Nm
-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).
-Note that
-.Cm CheckHostIP
-is not available for connects with a proxy command.
-.Pp
-.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 RemoteForward
-Specifies that a TCP/IP 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 a port number, and the second must be
-.Ar host:port .
-IPv6 addresses can be specified with an alternative syntax:
-.Ar host/port .
-Multiple forwardings may be specified, and additional
-forwardings can be given on the command line.
-Only the superuser can forward privileged ports.
-.It Cm RhostsAuthentication
-Specifies whether to try rhosts based authentication.
-Note that this
-declaration only affects the client side and has no effect whatsoever
-on security.
-Disabling rhosts authentication may reduce
-authentication time on slow connections when rhosts authentication is
-not used.
-Most servers do not permit RhostsAuthentication because it
-is not secure (see
-.Cm RhostsRSAAuthentication ) .
-The argument to this keyword must be
-.Dq yes
-or
-.Dq no .
-The default is
-.Dq yes .
-This option applies to protocol version 1 only.
-.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 yes .
-This option applies to protocol version 1 only.
-.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 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 SmartcardDevice
-Specifies which smartcard device to use. The argument to this keyword is
-the device
-.Nm
-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 ,
-.Nm
-will never automatically add host keys to the
-.Pa $HOME/.ssh/known_hosts
-file, and refuses to connect to hosts whose host key has changed.
-This provides maximum protection against trojan horse attacks,
-however, can be annoying when the
-.Pa /etc/ssh/ssh_known_hosts
-file is poorly maintained, or 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 ,
-.Nm
-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
-.Nm
-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 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 .
-Note that this option must be set to
-.Dq yes
-if
-.Cm RhostsAuthentication
-and
-.Cm RhostsRSAAuthentication
-authentications are needed 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 $HOME/.ssh/known_hosts .
-.It Cm UseRsh
-Specifies that rlogin/rsh should be used for this host.
-It is possible that the host does not at all support the
-.Nm
-protocol.
-This causes
-.Nm
-to immediately execute
-.Xr rsh 1 .
-All other options (except
-.Cm HostName )
-are ignored if this has been specified.
-The argument must be
-.Dq yes
-or
-.Dq no .
-.It Cm XAuthLocation
-Specifies the location of the
-.Xr xauth 1
-program.
-The default is
-.Pa /usr/X11R6/bin/xauth .
-.El
+may additionally obtain configuration data from
+a per-user configuration file and a system-wide configuration file.
+The file format and configuration options are described in
+.Xr ssh_config 5 .
 .Sh ENVIRONMENT
 .Nm
 will normally set the following environment variables:
@@ -1284,11 +732,11 @@
 .It Ev SSH_AUTH_SOCK
 Identifies the path of a unix-domain socket used to communicate with the
 agent.
-.It Ev SSH_CLIENT
-Identifies the client end of the connection.
+.It Ev SSH_CONNECTION
+Identifies the client and server ends of the connection.
 The variable contains
-three space-separated values: client ip-address, client port number,
-and server port number.
+four space-separated values: client ip-address, client port number,
+server ip-address and server port number.
 .It Ev SSH_ORIGINAL_COMMAND
 The variable contains the original command line if a forced command
 is executed.
@@ -1312,7 +760,12 @@
 .Pa $HOME/.ssh/environment ,
 and adds lines of the format
 .Dq VARNAME=value
-to the environment.
+to the environment if the file exists and if users are allowed to
+change their environment.
+See the
+.Cm PermitUserEnvironment
+option in
+.Xr sshd_config 5 .
 .Sh FILES
 .Bl -tag -width Ds
 .It Pa $HOME/.ssh/known_hosts
@@ -1357,13 +810,8 @@
 the convenience of the user.
 .It Pa $HOME/.ssh/config
 This is the per-user configuration file.
-The format of this file is described above.
-This file is used by the
-.Nm
-client.
-This file does not usually contain any sensitive information,
-but the recommended permissions are read/write for the user, and not
-accessible by others.
+The file format and configuration options are described in
+.Xr ssh_config 5 .
 .It Pa $HOME/.ssh/authorized_keys
 Lists the public keys (RSA/DSA) that can be used for logging in as this user.
 The format of this file is described in the
@@ -1398,19 +846,31 @@
 would then be able to fool host authentication.
 .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.
+The file format and configuration options are described in
+.Xr ssh_config 5 .
 .It Pa /etc/ssh/ssh_host_key, /etc/ssh/ssh_host_dsa_key, /etc/ssh/ssh_host_rsa_key
 These three files contain the private parts of the host keys
 and are used for
 .Cm RhostsRSAAuthentication
 and
 .Cm HostbasedAuthentication .
-Since they are readable only by root
+If the protocol version 1
+.Cm RhostsRSAAuthentication
+method is used,
 .Nm
-must be setuid root if these authentication methods are desired.
+must be setuid root, since the host key is readable only by root.
+For protocol version 2,
+.Nm
+uses
+.Xr ssh-keysign 8
+to access the host keys for
+.Cm HostbasedAuthentication .
+This eliminates the requirement that
+.Nm
+be setuid root when that authentication method is used.
+By default
+.Nm
+is not setuid root.
 .It Pa $HOME/.rhosts
 This file is used in
 .Pa \&.rhosts
@@ -1451,7 +911,7 @@
 having this file is to be able to use rhosts authentication with
 .Nm
 without permitting login with
-.Xr rlogin 1
+.Nm rlogin
 or
 .Xr rsh 1 .
 .It Pa /etc/hosts.equiv
@@ -1508,7 +968,6 @@
 Markus Friedl contributed the support for SSH
 protocol versions 1.5 and 2.0.
 .Sh SEE ALSO
-.Xr rlogin 1 ,
 .Xr rsh 1 ,
 .Xr scp 1 ,
 .Xr sftp 1 ,
@@ -1516,6 +975,8 @@
 .Xr ssh-agent 1 ,
 .Xr ssh-keygen 1 ,
 .Xr telnet 1 ,
+.Xr ssh_config 5 ,
+.Xr ssh-keysign 8 ,
 .Xr sshd 8
 .Rs
 .%A T. Ylonen