X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/5c63c2ab2e7e004fbe2458ed96b32e559d144999..32560f077f93eb11a8d199ada25e7f7dfec79af4:/ssh.1

diff --git a/ssh.1 b/ssh.1
index c371b7cf..4cc1738c 100644
--- a/ssh.1
+++ b/ssh.1
@@ -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 1.201 2005/03/01 10:40:27 djm Exp $
+.\" $OpenBSD: ssh.1,v 1.208 2005/05/23 23:32:46 djm Exp $
 .Dd September 25, 1999
 .Dt SSH 1
 .Os
@@ -43,42 +43,35 @@
 .Nd OpenSSH SSH client (remote login program)
 .Sh SYNOPSIS
 .Nm ssh
+.Bk -words
 .Op Fl 1246AaCfgkMNnqsTtVvXxY
 .Op Fl b Ar bind_address
 .Op Fl c Ar cipher_spec
-.Bk -words
 .Op Fl D Ar port
 .Op Fl e Ar escape_char
 .Op Fl F Ar configfile
 .Op Fl i Ar identity_file
-.Oo Fl L Xo
+.Oo Fl L\ \&
 .Sm off
 .Oo Ar bind_address : Oc
-.Ar port :
-.Ar host :
-.Ar hostport
+.Ar port : host : hostport
 .Sm on
-.Xc
 .Oc
 .Op Fl l Ar login_name
 .Op Fl m Ar mac_spec
 .Op Fl O Ar ctl_cmd
 .Op Fl o Ar option
-.Bk -words
 .Op Fl p Ar port
-.Ek
-.Oo Fl R Xo
+.Oo Fl R\ \&
 .Sm off
 .Oo Ar bind_address : Oc
-.Ar port :
-.Ar host :
-.Ar hostport
+.Ar port : host : hostport
 .Sm on
-.Xc
 .Oc
 .Op Fl S Ar ctl_path
 .Oo Ar user Ns @ Oc Ns Ar hostname
 .Op Ar command
+.Ek
 .Sh DESCRIPTION
 .Nm
 (SSH client) is a program for logging into a remote machine and for
@@ -116,9 +109,9 @@ or
 .Pa /etc/shosts.equiv
 on the remote machine, and the user names are
 the same on both sides, or if the files
-.Pa $HOME/.rhosts
+.Pa ~/.rhosts
 or
-.Pa $HOME/.shosts
+.Pa ~/.shosts
 exist in the user's home directory on the
 remote machine and contain a line containing the name of the client
 machine and the name of the user on that machine, the user is
@@ -127,7 +120,7 @@ Additionally, if the server can verify the client's
 host key (see
 .Pa /etc/ssh/ssh_known_hosts
 and
-.Pa $HOME/.ssh/known_hosts
+.Pa ~/.ssh/known_hosts
 in the
 .Sx FILES
 section), only then is login permitted.
@@ -135,7 +128,7 @@ This authentication method closes security holes due to IP
 spoofing, DNS spoofing and routing spoofing.
 [Note to the administrator:
 .Pa /etc/hosts.equiv ,
-.Pa $HOME/.rhosts ,
+.Pa ~/.rhosts ,
 and the rlogin/rsh protocol in general, are inherently insecure and should be
 disabled if security is desired.]
 .Pp
@@ -151,7 +144,7 @@ key pair for authentication purposes.
 The server knows the public key, and only the user knows the private key.
 .Pp
 The file
-.Pa $HOME/.ssh/authorized_keys
+.Pa ~/.ssh/authorized_keys
 lists the public keys that are permitted for logging in.
 When the user logs in, the
 .Nm
@@ -172,18 +165,18 @@ implements the RSA authentication protocol automatically.
 The user creates his/her RSA key pair by running
 .Xr ssh-keygen 1 .
 This stores the private key in
-.Pa $HOME/.ssh/identity
+.Pa ~/.ssh/identity
 and stores the public key in
-.Pa $HOME/.ssh/identity.pub
+.Pa ~/.ssh/identity.pub
 in the user's home directory.
 The user should then copy the
 .Pa identity.pub
 to
-.Pa $HOME/.ssh/authorized_keys
+.Pa ~/.ssh/authorized_keys
 in his/her home directory on the remote machine (the
 .Pa authorized_keys
 file corresponds to the conventional
-.Pa $HOME/.rhosts
+.Pa ~/.rhosts
 file, and has one key
 per line, though the lines can be very long).
 After this, the user can log in without giving the password.
@@ -213,12 +206,12 @@ password authentication are tried.
 The public key method is similar to RSA authentication described
 in the previous section and allows the RSA or DSA algorithm to be used:
 The client uses his private key,
-.Pa $HOME/.ssh/id_dsa
+.Pa ~/.ssh/id_dsa
 or
-.Pa $HOME/.ssh/id_rsa ,
+.Pa ~/.ssh/id_rsa ,
 to sign the session identifier and sends the result to the server.
 The server checks whether the matching public key is listed in
-.Pa $HOME/.ssh/authorized_keys
+.Pa ~/.ssh/authorized_keys
 and grants access if both the key is found and the signature is correct.
 The session identifier is derived from a shared Diffie-Hellman value
 and is only known to the client and the server.
@@ -372,7 +365,7 @@ electronic purse; another is going through firewalls.
 automatically maintains and checks a database containing
 identifications for all hosts it has ever been used with.
 Host keys are stored in
-.Pa $HOME/.ssh/known_hosts
+.Pa ~/.ssh/known_hosts
 in the user's home directory.
 Additionally, the file
 .Pa /etc/ssh/ssh_known_hosts
@@ -430,7 +423,7 @@ authenticate using the identities loaded into the agent.
 .It Fl a
 Disables forwarding of the authentication agent connection.
 .It Fl b Ar bind_address
-Specify the interface to transmit from on machines with multiple
+Specify the interface address to transmit from on machines with multiple
 interfaces or aliased addresses.
 .It Fl C
 Requests compression of all data (including stdin, stdout, stderr, and
@@ -486,14 +479,17 @@ The supported ciphers are
 .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
-  ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,
-    aes192-cbc,aes256-cbc''
+  ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,
+    arcfour256,arcfour,aes192-cbc,aes256-cbc,aes128-ctr,
+    aes192-ctr,aes256-ctr''
 .Ed
 .It Fl D Ar port
 Specifies a local
@@ -529,7 +525,7 @@ the system-wide configuration file
 .Pq Pa /etc/ssh/ssh_config
 will be ignored.
 The default for the per-user configuration file is
-.Pa $HOME/.ssh/config .
+.Pa ~/.ssh/config .
 .It Fl f
 Requests
 .Nm
@@ -555,11 +551,11 @@ private RSA key.
 Selects a file from which the identity (private key) for
 RSA or DSA authentication is read.
 The default is
-.Pa $HOME/.ssh/identity
+.Pa ~/.ssh/identity
 for protocol version 1, and
-.Pa $HOME/.ssh/id_rsa
+.Pa ~/.ssh/id_rsa
 and
-.Pa $HOME/.ssh/id_dsa
+.Pa ~/.ssh/id_dsa
 for protocol version 2.
 Identity files may also be specified on
 a per-host basis in the configuration file.
@@ -592,7 +588,7 @@ Port forwardings can also be specified in the configuration file.
 IPv6 addresses can be specified with an alternative syntax:
 .Sm off
 .Xo
-.Oo Ar bind_address / Oc
+.Op Ar bind_address No /
 .Ar port No / Ar host No /
 .Ar hostport
 .Xc
@@ -609,9 +605,9 @@ The
 .Ar bind_address
 of
 .Dq localhost
-indicates that the listening port be bound for local use only, while an 
-empty address or 
-.Dq *
+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 Fl l Ar login_name
 Specifies the user to log in as on the remote machine.
@@ -766,28 +762,29 @@ Privileged ports can be forwarded only when
 logging in as root on the remote machine.
 IPv6 addresses can be specified by enclosing the address in square braces or
 using an alternative syntax:
-.Xo
 .Sm off
-.Oo Ar bind_address / Oc
-.Ar host/port/hostport
-.Sm on
+.Xo
+.Op Ar bind_address No /
+.Ar host No / Ar port No /
+.Ar hostport
 .Xc .
+.Sm on
 .Pp
 By default, the listening socket on the server will be bound to the loopback
 interface only.
 This may be overriden by specifying a
 .Ar bind_address .
-An empty 
-.Ar bind_address , 
+An empty
+.Ar bind_address ,
 or the address
-.Ql *
+.Ql * ,
 indicates that the remote socket should listen on all interfaces.
 Specifying a remote
 .Ar bind_address
-will only succeed if the server's 
-.Cm GatewayPorts 
+will only succeed if the server's
+.Cm GatewayPorts
 option is enabled (see
-.Xr sshd_config 5 ).
+.Xr sshd_config 5 ) .
 .It Fl S Ar ctl_path
 Specifies the location of a control socket for connection sharing.
 Refer to the description of
@@ -837,10 +834,23 @@ 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.
+.Pp
+For this reason, X11 forwarding is subjected to X11 SECURITY extension
+restrictions by default.
+Please refer to the
+.Nm
+.Fl Y
+option and the
+.Cm ForwardX11Trusted
+directive in
+.Xr ssh_config 5
+for more information.
 .It Fl x
 Disables X11 forwarding.
 .It Fl Y
 Enables trusted X11 forwarding.
+Trusted X11 forwardings are not subjected to the X11 SECURITY extension
+controls.
 .El
 .Sh CONFIGURATION FILES
 .Nm
@@ -934,7 +944,7 @@ Set to the name of the user logging in.
 Additionally,
 .Nm
 reads
-.Pa $HOME/.ssh/environment ,
+.Pa ~/.ssh/environment ,
 and adds lines of the format
 .Dq VARNAME=value
 to the environment if the file exists and if users are allowed to
@@ -945,13 +955,13 @@ option in
 .Xr sshd_config 5 .
 .Sh FILES
 .Bl -tag -width Ds
-.It Pa $HOME/.ssh/known_hosts
+.It Pa ~/.ssh/known_hosts
 Records host keys for all hosts the user has logged into that are not
 in
 .Pa /etc/ssh/ssh_known_hosts .
 See
 .Xr sshd 8 .
-.It Pa $HOME/.ssh/identity, $HOME/.ssh/id_dsa, $HOME/.ssh/id_rsa
+.It Pa ~/.ssh/identity, ~/.ssh/id_dsa, ~/.ssh/id_rsa
 Contains the authentication identity of the user.
 They are for protocol 1 RSA, protocol 2 DSA, and protocol 2 RSA, respectively.
 These files
@@ -963,21 +973,21 @@ ignores a private key file if it is accessible by others.
 It is possible to specify a passphrase when
 generating the key; the passphrase will be used to encrypt the
 sensitive part of this file using 3DES.
-.It Pa $HOME/.ssh/identity.pub, $HOME/.ssh/id_dsa.pub, $HOME/.ssh/id_rsa.pub
+.It Pa ~/.ssh/identity.pub, ~/.ssh/id_dsa.pub, ~/.ssh/id_rsa.pub
 Contains the public key for authentication (public part of the
 identity file in human-readable form).
 The contents of the
-.Pa $HOME/.ssh/identity.pub
+.Pa ~/.ssh/identity.pub
 file should be added to the file
-.Pa $HOME/.ssh/authorized_keys
+.Pa ~/.ssh/authorized_keys
 on all machines
 where the user wishes to log in using protocol version 1 RSA authentication.
 The contents of the
-.Pa $HOME/.ssh/id_dsa.pub
+.Pa ~/.ssh/id_dsa.pub
 and
-.Pa $HOME/.ssh/id_rsa.pub
+.Pa ~/.ssh/id_rsa.pub
 file should be added to
-.Pa $HOME/.ssh/authorized_keys
+.Pa ~/.ssh/authorized_keys
 on all machines
 where the user wishes to log in using protocol version 2 DSA/RSA authentication.
 These files are not
@@ -985,13 +995,13 @@ sensitive and can (but need not) be readable by anyone.
 These files are
 never used automatically and are not necessary; they are only provided for
 the convenience of the user.
-.It Pa $HOME/.ssh/config
+.It Pa ~/.ssh/config
 This is the per-user configuration file.
 The file format and configuration options are described in
 .Xr ssh_config 5 .
 Because of the potential for abuse, this file must have strict permissions:
 read/write for the user, and not accessible by others.
-.It Pa $HOME/.ssh/authorized_keys
+.It Pa ~/.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
 .Xr sshd 8
@@ -1051,7 +1061,7 @@ be setuid root when that authentication method is used.
 By default
 .Nm
 is not setuid root.
-.It Pa $HOME/.rhosts
+.It Pa ~/.rhosts
 This file is used in
 .Cm RhostsRSAAuthentication
 and
@@ -1081,12 +1091,12 @@ authentication before permitting log in.
 If the server machine does not have the client's host key in
 .Pa /etc/ssh/ssh_known_hosts ,
 it can be stored in
-.Pa $HOME/.ssh/known_hosts .
+.Pa ~/.ssh/known_hosts .
 The easiest way to do this is to
 connect back to the client from the server machine using ssh; this
 will automatically add the host key to
-.Pa $HOME/.ssh/known_hosts .
-.It Pa $HOME/.shosts
+.Pa ~/.ssh/known_hosts .
+.It Pa ~/.shosts
 This file is used exactly the same way as
 .Pa .rhosts .
 The purpose for
@@ -1126,7 +1136,7 @@ when the user logs in just before the user's shell (or command) is started.
 See the
 .Xr sshd 8
 manual page for more information.
-.It Pa $HOME/.ssh/rc
+.It Pa ~/.ssh/rc
 Commands in this file are executed by
 .Nm
 when the user logs in just before the user's shell (or command) is
@@ -1134,7 +1144,7 @@ started.
 See the
 .Xr sshd 8
 manual page for more information.
-.It Pa $HOME/.ssh/environment
+.It Pa ~/.ssh/environment
 Contains additional definitions for environment variables, see section
 .Sx ENVIRONMENT
 above.