diff options
Diffstat (limited to 'crypto/openssh/sshd.8')
-rw-r--r-- | crypto/openssh/sshd.8 | 111 |
1 files changed, 80 insertions, 31 deletions
diff --git a/crypto/openssh/sshd.8 b/crypto/openssh/sshd.8 index 6e283b0..117c970 100644 --- a/crypto/openssh/sshd.8 +++ b/crypto/openssh/sshd.8 @@ -34,9 +34,9 @@ .\" (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: sshd.8,v 1.234 2006/08/21 08:15:57 dtucker Exp $ +.\" $OpenBSD: sshd.8,v 1.246 2008/07/02 02:24:18 djm Exp $ .\" $FreeBSD$ -.Dd September 25, 1999 +.Dd $Mdocdate: July 2 2008 $ .Dt SSHD 8 .Os .Sh NAME @@ -45,8 +45,9 @@ .Sh SYNOPSIS .Nm sshd .Bk -words -.Op Fl 46Ddeiqt +.Op Fl 46DdeiqTt .Op Fl b Ar bits +.Op Fl C Ar connection_spec .Op Fl f Ar config_file .Op Fl g Ar login_grace_time .Op Fl h Ar host_key_file @@ -59,8 +60,11 @@ .Nm (OpenSSH Daemon) is the daemon program for .Xr ssh 1 . -Together these programs replace rlogin and rsh, and -provide secure encrypted communications between two untrusted hosts +Together these programs replace +.Xr rlogin 1 +and +.Xr rsh 1 , +and provide secure encrypted communications between two untrusted hosts over an insecure network. .Pp .Nm @@ -97,7 +101,25 @@ Forces to use IPv6 addresses only. .It Fl b Ar bits Specifies the number of bits in the ephemeral protocol version 1 -server key (default 768). +server key (default 1024). +.It Fl C Ar connection_spec +Specify the connection parameters to use for the +.Fl T +extended test mode. +If provided, any +.Cm Match +directives in the configuration file +that would apply to the specified user, host, and address will be set before +the configuration is written to standard output. +The connection parameters are supplied as keyword=value pairs. +The keywords are +.Dq user , +.Dq host , +and +.Dq addr . +All are required and may be supplied in any order, either with multiple +.Fl C +options or as a comma-separated list. .It Fl D When this option is specified, .Nm @@ -118,7 +140,7 @@ Maximum is 3. When this option is specified, .Nm will send the output to the standard error instead of the system log. -.It Fl f Ar configuration_file +.It Fl f Ar config_file Specifies the name of the configuration file. The default is .Pa /etc/ssh/sshd_config . @@ -139,6 +161,8 @@ host key files are normally not readable by anyone but root). The default is .Pa /etc/ssh/ssh_host_key for protocol version 1, and +.Pa /etc/ssh/ssh_host_rsa_key +and .Pa /etc/ssh/ssh_host_dsa_key for protocol version 2. It is possible to have multiple host key files for @@ -187,6 +211,15 @@ Quiet mode. Nothing is sent to the system log. Normally the beginning, authentication, and termination of each connection is logged. +.It Fl T +Extended test mode. +Check the validity of the configuration file, output the effective configuration +to stdout and then exit. +Optionally, +.Cm Match +rules may be applied by specifying the connection parameters using one or more +.Fl C +options. .It Fl t Test mode. Only check the validity of the configuration file and sanity of the keys. @@ -272,7 +305,7 @@ The client selects the encryption algorithm to use from those offered by the server. Additionally, session integrity is provided through a cryptographic message authentication code -(hmac-sha1 or hmac-md5). +(hmac-md5, hmac-sha1, umac-64 or hmac-ripemd160). .Pp Finally, the server and the client enter an authentication dialog. The client tries to authenticate itself using @@ -298,8 +331,9 @@ on Tru64, a leading .Ql \&*LOCKED\&* on FreeBSD and a leading -.Ql \&!! -on Linux). If there is a requirement to disable password authentication +.Ql \&! +on most Linuxes). +If there is a requirement to disable password authentication for the account while allowing still public-key, then the passwd field should be set to something other than these values (eg .Ql NP @@ -500,23 +534,27 @@ This option is automatically disabled if .Cm UseLogin is enabled. .It Cm from="pattern-list" -Specifies that in addition to public key authentication, the canonical name -of the remote host must be present in the comma-separated list of -patterns. -The purpose -of this option is to optionally increase security: public key authentication -by itself does not trust the network or name servers or anything (but -the key); however, if somebody somehow steals the key, the key -permits an intruder to log in from anywhere in the world. -This additional option makes using a stolen key more difficult (name -servers and/or routers would have to be compromised in addition to -just the key). -.Pp +Specifies that in addition to public key authentication, either the canonical +name of the remote host or its IP address must be present in the +comma-separated list of patterns. See .Sx PATTERNS in .Xr ssh_config 5 for more information on patterns. +.Pp +In addition to the wildcard matching that may be applied to hostnames or +addresses, a +.Cm from +stanza may match IP addressess using CIDR address/masklen notation. +.Pp +The purpose of this option is to optionally increase security: public key +authentication by itself does not trust the network or name servers or +anything (but the key); however, if somebody somehow steals the key, the key +permits an intruder to log in from anywhere in the world. +This additional option makes using a stolen key more difficult (name +servers and/or routers would have to be compromised in addition to +just the key). .It Cm no-agent-forwarding Forbids authentication agent forwarding when this key is used for authentication. @@ -528,6 +566,9 @@ This might be used, e.g. in connection with the option. .It Cm no-pty Prevents tty allocation (a request to allocate a pty will fail). +.It Cm no-user-rc +Disables execution of +.Pa ~/.ssh/rc . .It Cm no-X11-forwarding Forbids X11 forwarding when this key is used for authentication. Any X11 forward requests by the client will return an error. @@ -679,6 +720,13 @@ This file is used in exactly the same way as but allows host-based authentication without permitting login with rlogin/rsh. .Pp +.It ~/.ssh/ +This directory is the default location for all user-specific configuration +and authentication information. +There is no general requirement to keep the entire contents of this directory +secret, but the recommended permissions are read/write/execute for the user, +and not accessible by others. +.Pp .It ~/.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 above. @@ -759,15 +807,6 @@ This file is used in exactly the same way as but allows host-based authentication without permitting login with rlogin/rsh. .Pp -.It /etc/ssh/ssh_known_hosts -Systemwide list of known host keys. -This file should be prepared by the -system administrator to contain the public host keys of all machines in the -organization. -The format of this file is described above. -This file should be writable only by root/the owner and -should be world-readable. -.Pp .It /etc/ssh/ssh_host_key .It /etc/ssh/ssh_host_dsa_key .It /etc/ssh/ssh_host_rsa_key @@ -791,6 +830,15 @@ the user so their contents can be copied to known hosts files. These files are created using .Xr ssh-keygen 1 . .Pp +.It /etc/ssh/ssh_known_hosts +Systemwide list of known host keys. +This file should be prepared by the +system administrator to contain the public host keys of all machines in the +organization. +The format of this file is described above. +This file should be writable only by root/the owner and +should be world-readable. +.Pp .It /etc/ssh/sshd_config Contains configuration data for .Nm sshd . @@ -827,6 +875,7 @@ The content of this file is not sensitive; it can be world-readable. .Xr ssh-add 1 , .Xr ssh-agent 1 , .Xr ssh-keygen 1 , +.Xr ssh-keyscan 1 , .Xr chroot 2 , .Xr hosts_access 5 , .Xr login.conf 5 , |