diff options
author | Damien Miller <djm@mindrot.org> | 1999-10-28 14:03:14 +1000 |
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committer | Damien Miller <djm@mindrot.org> | 1999-10-28 14:03:14 +1000 |
commit | 062307657e30c9b970514eb53b4b743f9d571231 (patch) | |
tree | 04b1d6b094442720b4197eb442ee53c010cdc1d7 /sshd.8 | |
parent | 7f6ea0264d01aa40b20df8dc75141631479da054 (diff) |
Big rename ssh* -> openssh*
Diffstat (limited to 'sshd.8')
-rw-r--r-- | sshd.8 | 781 |
1 files changed, 0 insertions, 781 deletions
diff --git a/sshd.8 b/sshd.8 deleted file mode 100644 index 981c5ff7..00000000 --- a/sshd.8 +++ /dev/null @@ -1,781 +0,0 @@ -.\" -*- nroff -*- -.\" -.\" sshd.8.in -.\" -.\" Author: Tatu Ylonen <ylo@cs.hut.fi> -.\" -.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland -.\" All rights reserved -.\" -.\" Created: Sat Apr 22 21:55:14 1995 ylo -.\" -.\" $Id: sshd.8,v 1.1 1999/10/27 03:42:46 damien Exp $ -.\" -.Dd September 25, 1999 -.Dt SSHD 8 -.Os -.Sh NAME -.Nm sshd -.Nd secure shell daemon -.Sh SYNOPSIS -.Nm sshd -.Op Fl diq -.Op Fl b Ar bits -.Op Fl f Ar config_file -.Op Fl g Ar login_grace_time -.Op Fl h Ar host_key_file -.Op Fl k Ar key_gen_time -.Op Fl p Ar port -.Sh DESCRIPTION -.Nm -(Secure Shell Daemon) is the daemon program for -.Xr ssh 1 . -Together these programs replace rlogin and rsh programs, and -provide secure encrypted communications between two untrusted hosts -over an insecure network. The programs are intended to be as easy to -install and use as possible. -.Pp -.Nm -is the daemon that listens for connections from clients. It is -normally started at boot from -.Pa /etc/rc . -It forks a new -daemon for each incoming connection. The forked daemons handle -key exchange, encryption, authentication, command execution, -and data exchange. -.Pp -.Nm -works as follows. Each host has a host-specific RSA key -(normally 1024 bits) used to identify the host. Additionally, when -the daemon starts, it generates a server RSA key (normally 768 bits). -This key is normally regenerated every hour if it has been used, and -is never stored on disk. -.Pp -Whenever a client connects the daemon, the daemon sends its host -and server public keys to the client. The client compares the -host key against its own database to verify that it has not changed. -The client then generates a 256 bit random number. It encrypts this -random number using both the host key and the server key, and sends -the encrypted number to the server. Both sides then start to use this -random number as a session key which is used to encrypt all further -communications in the session. The rest of the session is encrypted -using a conventional cipher, currently Blowfish and 3DES, with 3DES -being is used by default. The client selects the encryption algorithm -to use from those offered by the server. -.Pp -Next, the server and the client enter an authentication dialog. The -client tries to authenticate itself using -.Pa .rhosts -authentication, -.Pa .rhosts -authentication combined with RSA host -authentication, RSA challenge-response authentication, or password -based authentication. -.Pp -Rhosts authentication is normally disabled -because it is fundamentally insecure, but can be enabled in the server -configuration file if desired. System security is not improved unless -.Xr rshd 8 , -.Xr rlogind 8 , -.Xr rexecd 8 , -and -.Xr rexd 8 -are disabled (thus completely disabling -.Xr rlogin 1 -and -.Xr rsh 1 -into that machine). -.Pp -If the client successfully authenticates itself, a dialog for -preparing the session is entered. At this time the client may request -things like allocating a pseudo-tty, forwarding X11 connections, -forwarding TCP/IP connections, or forwarding the authentication agent -connection over the secure channel. -.Pp -Finally, the client either requests a shell or execution of a command. -The sides then enter session mode. In this mode, either side may send -data at any time, and such data is forwarded to/from the shell or -command on the server side, and the user terminal in the client side. -.Pp -When the user program terminates and all forwarded X11 and other -connections have been closed, the server sends command exit status to -the client, and both sides exit. -.Pp -.Nm -can be configured using command-line options or a configuration -file. Command-line options override values specified in the -configuration file. -.Pp -The options are as follows: -.Bl -tag -width Ds -.It Fl b Ar bits -Specifies the number of bits in the server key (default 768). -.Pp -.It Fl d -Debug mode. The server sends verbose debug output to the system -log, and does not put itself in the background. The server also will -not fork and will only process one connection. This option is only -intended for debugging for the server. -.It Fl f Ar configuration_file -Specifies the name of the configuration file. The default is -.Pa /etc/sshd_config . -.Nm -refuses to start if there is no configuration file. -.It Fl g Ar login_grace_time -Gives the grace time for clients to authenticate themselves (default -300 seconds). If the client fails to authenticate the user within -this many seconds, the server disconnects and exits. A value of zero -indicates no limit. -.It Fl h Ar host_key_file -Specifies the file from which the host key is read (default -.Pa /etc/ssh_host_key ) . -This option must be given if -.Nm -is not run as root (as the normal -host file is normally not readable by anyone but root). -.It Fl i -Specifies that -.Nm -is being run from inetd. -.Nm -is normally not run -from inetd because it needs to generate the server key before it can -respond to the client, and this may take tens of seconds. Clients -would have to wait too long if the key was regenerated every time. -However, with small key sizes (e.g. 512) using -.Nm -from inetd may -be feasible. -.It Fl k Ar key_gen_time -Specifies how often the server key is regenerated (default 3600 -seconds, or one hour). The motivation for regenerating the key fairly -often is that the key is not stored anywhere, and after about an hour, -it becomes impossible to recover the key for decrypting intercepted -communications even if the machine is cracked into or physically -seized. A value of zero indicates that the key will never be regenerated. -.It Fl p Ar port -Specifies the port on which the server listens for connections -(default 22). -.It Fl q -Quiet mode. Nothing is sent to the system log. Normally the beginning, -authentication, and termination of each connection is logged. -.It Fl Q -Do not print an error message if RSA support is missing. -.El -.Sh CONFIGURATION FILE -.Nm -reads configuration data from -.Pa /etc/sshd_config -(or the file specified with -.Fl f -on the command line). The file -contains keyword-value pairs, one per line. Lines starting with -.Ql # -and empty lines are interpreted as comments. -.Pp -The following keywords are possible. -.Bl -tag -width Ds -.It Cm AFSTokenPassing -Specifies whether an AFS token may be forwarded to the server. Default is -.Dq yes . -.It Cm AllowGroups -This keyword can be followed by a number of group names, separated -by spaces. If specified, login is allowed only for users whose primary -group matches one of the patterns. -.Ql \&* -and -.Ql ? -can be used as -wildcards in the patterns. Only group names are valid, a numerical group -id isn't recognized. By default login is allowed regardless of -the primary group. -.Pp -.It Cm AllowUsers -This keyword can be followed by a number of user names, separated -by spaces. If specified, login is allowed only for users names that -match one of the patterns. -.Ql \&* -and -.Ql ? -can be used as -wildcards in the patterns. Only user names are valid, a numerical user -id isn't recognized. By default login is allowed regardless of -the user name. -.Pp -.It Cm CheckMail -Specifies whether -.Nm -should check for new mail for interactive logins. -The default is -.Dq no . -.It Cm DenyGroups -This keyword can be followed by a number of group names, separated -by spaces. Users whose primary group matches one of the patterns -aren't allowed to log in. -.Ql \&* -and -.Ql ? -can be used as -wildcards in the patterns. Only group names are valid, a numerical group -id isn't recognized. By default login is allowed regardless of -the primary group. -.Pp -.It Cm DenyUsers -This keyword can be followed by a number of user names, separated -by spaces. Login is allowed disallowed for user names that match -one of the patterns. -.Ql \&* -and -.Ql ? -can be used as -wildcards in the patterns. Only user names are valid, a numerical user -id isn't recognized. By default login is allowed regardless of -the user name. -.Pp -.It Cm FascistLogging -Specifies whether to use verbose logging. Verbose logging violates -the privacy of users and is not recommended. The argument must be -.Dq yes -or -.Dq no . -The default is -.Dq no . -.It Cm HostKey -Specifies the file containing the private host key (default -.Pa /etc/ssh_host_key ) . -Note that -.Nm -does not start if this file is group/world-accessible. -.It Cm IgnoreRhosts -Specifies that rhosts and shosts files will not be used in -authentication. -.Pa /etc/hosts.equiv -and -.Pa /etc/shosts.equiv -are still used. The default is -.Dq no . -.It Cm KeepAlive -Specifies whether the system should send 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. On the other hand, if keepalives are not send, -sessions may hang indefinitely on the server, leaving -.Dq ghost -users and consuming server resources. -.Pp -The default is -.Dq yes -(to send keepalives), and the server will notice -if the network goes down or the client host reboots. This avoids -infinitely hanging sessions. -.Pp -To disable keepalives, the value should be set to -.Dq no -in both the server and the client configuration files. -.It Cm KerberosAuthentication -Specifies whether Kerberos authentication is allowed. This can -be in the form of a Kerberos ticket, or if -.Cm PasswordAuthentication -is yes, the password provided by the user will be validated through -the Kerberos KDC. Default is -.Dq yes . -.It Cm KerberosOrLocalPasswd -If set then if password authentication through Kerberos fails then -the password will be validated via any additional local mechanism -such as -.Pa /etc/passwd -or SecurID. Default is -.Dq yes . -.It Cm KerberosTgtPassing -Specifies whether a Kerberos TGT may be forwarded to the server. -Default is -.Dq no , -as this only works when the Kerberos KDC is actually an AFS kaserver. -.It Cm KerberosTicketCleanup -Specifies whether to automatically destroy the user's ticket cache -file on logout. Default is -.Dq yes . -.It Cm KeyRegenerationInterval -The server key is automatically regenerated after this many seconds -(if it has been used). The purpose of regeneration is to prevent -decrypting captured sessions by later breaking into the machine and -stealing the keys. The key is never stored anywhere. If the value is -0, the key is never regenerated. The default is 3600 -(seconds). -.It Cm ListenAddress -Specifies what local address -.Nm -should listen on. -The default is to listen to all local addresses. -.It Cm LoginGraceTime -The server disconnects after this time if the user has not -successfully logged in. If the value is 0, there is no time limit. -The default is 600 (seconds). -.It Cm PasswordAuthentication -Specifies whether password authentication is allowed. -The default is -.Dq yes . -.It Cm PermitEmptyPasswords -When password authentication is allowed, it specifies whether the -server allows login to accounts with empty password strings. The default -is -.Dq yes . -.It Cm PermitRootLogin -Specifies whether the root can log in using -.Xr ssh 1 . -The argument must be -.Dq yes , -.Dq without-password -or -.Dq no . -The default is -.Dq yes . -If this options is set to -.Dq without-password -only password authentication is disabled for root. -.Pp -Root login with RSA authentication when the -.Ar command -option has been -specified will be allowed regardless of the value of this setting -(which may be useful for taking remote backups even if root login is -normally not allowed). -.It Cm Port -Specifies the port number that -.Nm -listens on. The default is 22. -.It Cm PrintMotd -Specifies whether -.Nm -should print -.Pa /etc/motd -when a user logs in interactively. (On some systems it is also -printed by the shell, -.Pa /etc/profile , -or equivalent.) The default is -.Dq yes . -.It Cm QuietMode -Specifies whether the system runs in quiet mode. In quiet mode, -nothing is logged in the system log, except fatal errors. The default -is -.Dq no . -.It Cm RandomSeed -Obsolete. Random number generation uses other techniques. -.It Cm RhostsAuthentication -Specifies whether authentication using rhosts or /etc/hosts.equiv -files is sufficient. Normally, this method should not be permitted -because it is insecure. -.Cm RhostsRSAAuthentication -should be used -instead, because it performs RSA-based host authentication in addition -to normal rhosts or /etc/hosts.equiv authentication. -The default is -.Dq no . -.It Cm RhostsRSAAuthentication -Specifies whether rhosts or /etc/hosts.equiv authentication together -with successful RSA host authentication is allowed. The default is -.Dq yes . -.It Cm RSAAuthentication -Specifies whether pure RSA authentication is allowed. The default is -.Dq yes . -.It Cm ServerKeyBits -Defines the number of bits in the server key. The minimum value is -512, and the default is 768. -.It Cm SkeyAuthentication -Specifies whether -.Xr skey 1 -authentication is allowed. The default is -.Dq yes . -Note that s/key authentication is enabled only if -.Cm PasswordAuthentication -is allowed, too. -.It Cm StrictModes -Specifies whether -.Nm -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 -.Dq yes . -.It Cm SyslogFacility -Gives the facility code that is used when logging messages from -.Nm sshd . -The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, -LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. The default is AUTH. -.It Cm UseLogin -Specifies whether -.Xr login 1 -is used. The default is -.Dq no . -.It Cm X11Forwarding -Specifies whether X11 forwarding is permitted. The default is -.Dq yes . -Note that disabling X11 forwarding does not improve security in any -way, as users can always install their own forwarders. -.It Cm X11DisplayOffset -Specifies the first display number available for -.Nm sshd Ns 's -X11 forwarding. This prevents -.Nm -from interfering with real X11 servers. -.El -.Sh LOGIN PROCESS -When a user successfully logs in, -.Nm -does the following: -.Bl -enum -offset indent -.It -If the login is on a tty, and no command has been specified, -prints last login time and -.Pa /etc/motd -(unless prevented in the configuration file or by -.Pa $HOME/.hushlogin ; -see the -.Sx FILES -section). -.It -If the login is on a tty, records login time. -.It -Checks -.Pa /etc/nologin ; -if it exists, prints contents and quits -(unless root). -.It -Changes to run with normal user privileges. -.It -Sets up basic environment. -.It -Reads -.Pa $HOME/.ssh/environment -if it exists. -.It -Changes to user's home directory. -.It -If -.Pa $HOME/.ssh/rc -exists, runs it; else if -.Pa /etc/sshrc -exists, runs -it; otherwise runs xauth. The -.Dq rc -files are given the X11 -authentication protocol and cookie in standard input. -.It -Runs user's shell or command. -.El -.Sh AUTHORIZED_KEYS FILE FORMAT -The -.Pa $HOME/.ssh/authorized_keys -file lists the RSA keys that are -permitted for RSA authentication. Each line of the file contains one -key (empty lines and lines starting with a -.Ql # -are ignored as -comments). Each line consists of the following fields, separated by -spaces: options, bits, exponent, modulus, comment. The options field -is optional; its presence is determined by whether the line starts -with a number or not (the option field never starts with a number). -The bits, exponent, modulus and comment fields give the RSA key; the -comment field is not used for anything (but may be convenient for the -user to identify the key). -.Pp -Note that lines in this file are usually several hundred bytes long -(because of the size of the RSA key modulus). You don't want to type -them in; instead, copy the -.Pa identity.pub -file and edit it. -.Pp -The options (if present) consists of comma-separated option -specifications. No spaces are permitted, except within double quotes. -The following option specifications are supported: -.Bl -tag -width Ds -.It Cm from="pattern-list" -Specifies that in addition to RSA authentication, the canonical name -of the remote host must be present in the comma-separated list of -patterns ('*' and '?' serve as wildcards). The list may also contain -patterns negated by prefixing them with '!'; if the canonical host -name matches a negated pattern, the key is not accepted. The purpose -of this option is to optionally increase security: RSA 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 command="command" -Specifies that the command is executed whenever this key is used for -authentication. The command supplied by the user (if any) is ignored. -The command is run on a pty if the connection requests a pty; -otherwise it is run without a tty. A quote may be included in the -command by quoting it with a backslash. This option might be useful -to restrict certain RSA keys to perform just a specific operation. An -example might be a key that permits remote backups but nothing -else. Notice that the client may specify TCP/IP and/or X11 -forwardings unless they are explicitly prohibited. -.It Cm environment="NAME=value" -Specifies that the string is to be added to the environment when -logging in using this key. Environment variables set this way -override other default environment values. Multiple options of this -type are permitted. -.It Cm no-port-forwarding -Forbids TCP/IP forwarding when this key is used for authentication. -Any port forward requests by the client will return an error. This -might be used, e.g., in connection with the -.Cm command -option. -.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. -.It Cm no-agent-forwarding -Forbids authentication agent forwarding when this key is used for -authentication. -.It Cm no-pty -Prevents tty allocation (a request to allocate a pty will fail). -.El -.Ss Examples -1024 33 12121.\|.\|.\|312314325 ylo@foo.bar -.Pp -from="*.niksula.hut.fi,!pc.niksula.hut.fi" 1024 35 23.\|.\|.\|2334 ylo@niksula -.Pp -command="dump /home",no-pty,no-port-forwarding 1024 33 23.\|.\|.\|2323 backup.hut.fi -.Sh SSH_KNOWN_HOSTS FILE FORMAT -The -.Pa /etc/ssh_known_hosts -and -.Pa $HOME/.ssh/known_hosts -files contain host public keys for all known hosts. The global file should -be prepared by the admistrator (optional), and the per-user file is -maintained automatically: whenever the user connects an unknown host -its key is added to the per-user file. -.Pp -Each line in these files contains the following fields: hostnames, -bits, exponent, modulus, comment. The fields are separated by spaces. -.Pp -Hostnames is a comma-separated list of patterns ('*' and '?' act as -wildcards); each pattern in turn is matched against the canonical host -name (when authenticating a client) or against the user-supplied -name (when authenticating a server). A pattern may also be preceded -by -.Ql ! -to indicate negation: if the host name matches a negated -pattern, it is not accepted (by that line) even if it matched another -pattern on the line. -.Pp -Bits, exponent, and modulus are taken directly from the host key; they -can be obtained, e.g., from -.Pa /etc/ssh_host_key.pub . -The optional comment field continues to the end of the line, and is not used. -.Pp -Lines starting with -.Ql # -and empty lines are ignored as comments. -.Pp -When performing host authentication, authentication is accepted if any -matching line has the proper key. It is thus permissible (but not -recommended) to have several lines or different host keys for the same -names. This will inevitably happen when short forms of host names -from different domains are put in the file. It is possible -that the files contain conflicting information; authentication is -accepted if valid information can be found from either file. -.Pp -Note that the lines in these files are typically hundreds of characters -long, and you definitely don't want to type in the host keys by hand. -Rather, generate them by a script -or by taking -.Pa /etc/ssh_host_key.pub -and adding the host names at the front. -.Ss Examples -closenet,closenet.hut.fi,.\|.\|.\|,130.233.208.41 1024 37 159.\|.\|.93 closenet.hut.fi -.Sh FILES -.Bl -tag -width Ds -.It Pa /etc/sshd_config -Contains configuration data for -.Nm sshd . -This file should be writable by root only, but it is recommended -(though not necessary) that it be world-readable. -.It Pa /etc/ssh_host_key -Contains the private part of the host key. -This file should only be owned by root, readable only by root, and not -accessible to others. -Note that -.Nm -does not start if this file is group/world-accessible. -.It Pa /etc/ssh_host_key.pub -Contains the public part of the host key. -This file should be world-readable but writable only by -root. Its contents should match the private part. This file is not -really used for anything; it is only provided for the convenience of -the user so its contents can be copied to known hosts files. -These two files are created using -.Xr ssh-keygen 1 . -.It Pa /var/run/sshd.pid -Contains the process ID of the -.Nm -listening for connections (if there are several daemons running -concurrently for different ports, this contains the pid of the one -started last). The contents of this file are not sensitive; it can be -world-readable. -.It Pa $HOME/.ssh/authorized_keys -Lists the RSA keys that can be used to log into the user's account. -This file must be readable by root (which may on some machines imply -it being world-readable if the user's home directory resides on an NFS -volume). It is recommended that it not be accessible by others. The -format of this file is described above. -.It Pa /etc/ssh_known_hosts -This file is consulted when using rhosts with RSA host -authentication to check the public key of the host. The key must be -listed in this file to be accepted. -.It Pa $HOME/.ssh/known_hosts -The client uses this file -and -.Pa /etc/ssh_known_hosts -to verify that the remote host is the one we intended to -connect. These files should be writable only by root/the owner. -.Pa /etc/ssh_known_hosts -should be world-readable, and -.Pa $HOME/.ssh/known_hosts -can but need not be world-readable. -.It Pa /etc/nologin -If this file exists, -.Nm -refuses to let anyone except root log in. The contents of the file -are displayed to anyone trying to log in, and non-root connections are -refused. The file should be world-readable. -.It Pa /etc/hosts.allow, /etc/hosts.deny -If compiled with -.Sy LIBWRAP -support, tcp-wrappers access controls may be defined here as described in -.Xr hosts_access 5 . -.It Pa $HOME/.rhosts -This file contains host-username pairs, separated by a space, one per -line. The given user on the corresponding host is permitted to log in -without password. The same file is used by rlogind and rshd. -The file must -be writable only by the user; it is recommended that it not be -accessible by others. -.Pp -If is also possible to use netgroups in the file. Either host or user -name may be of the form +@groupname to specify all hosts or all users -in the group. -.It Pa $HOME/.shosts -For ssh, -this file is exactly the same as for -.Pa .rhosts . -However, this file is -not used by rlogin and rshd, so using this permits access using SSH only. -.Pa /etc/hosts.equiv -This file is used during -.Pa .rhosts -authentication. In the -simplest form, this file contains host names, one per line. Users on -those hosts are permitted to log in without a password, provided they -have the same user name on both machines. The host name may also be -followed by a user name; such users are permitted to log in as -.Em any -user on this machine (except root). Additionally, the syntax -.Dq +@group -can be used to specify netgroups. Negated entries start with -.Ql \&- . -.Pp -If the client host/user is successfully matched in this file, login is -automatically permitted provided the client and server user names are the -same. Additionally, successful RSA host authentication is normally -required. This file must be writable only by root; it is recommended -that it be world-readable. -.Pp -.Sy "Warning: It is almost never a good idea to use user names in" -.Pa hosts.equiv . -Beware that it really means that the named user(s) can log in as -.Em anybody , -which includes bin, daemon, adm, and other accounts that own critical -binaries and directories. Using a user name practically grants the -user root access. The only valid use for user names that I can think -of is in negative entries. -.Pp -Note that this warning also applies to rsh/rlogin. -.It Pa /etc/shosts.equiv -This is processed exactly as -.Pa /etc/hosts.equiv . -However, this file may be useful in environments that want to run both -rsh/rlogin and ssh. -.It Pa $HOME/.ssh/environment -This file is read into the environment at login (if it exists). It -can only contain empty lines, comment lines (that start with -.Ql # ) , -and assignment lines of the form name=value. The file should be writable -only by the user; it need not be readable by anyone else. -.It Pa $HOME/.ssh/rc -If this file exists, it is run with /bin/sh after reading the -environment files but before starting the user's shell or command. If -X11 spoofing is in use, this will receive the "proto cookie" pair in -standard input (and -.Ev DISPLAY -in environment). This must call -.Xr xauth 1 -in that case. -.Pp -The primary purpose of this file is to run any initialization routines -which may be needed before the user's home directory becomes -accessible; AFS is a particular example of such an environment. -.Pp -This file will probably contain some initialization code followed by -something similar to: "if read proto cookie; then echo add $DISPLAY -$proto $cookie | xauth -q -; fi". -.Pp -If this file does not exist, -.Pa /etc/sshrc -is run, and if that -does not exist either, xauth is used to store the cookie. -.Pp -This file should be writable only by the user, and need not be -readable by anyone else. -.It Pa /etc/sshrc -Like -.Pa $HOME/.ssh/rc . -This can be used to specify -machine-specific login-time initializations globally. This file -should be writable only by root, and should be world-readable. -.Sh AUTHOR -Tatu Ylonen <ylo@cs.hut.fi> -.Pp -Information about new releases, mailing lists, and other related -issues can be found from the SSH WWW home page: -.Pp -.Dl http://www.cs.hut.fi/ssh. -.Pp -OpenSSH -is a derivative of the original (free) ssh 1.2.12 release, but with bugs -removed and newer features re-added. Rapidly after the 1.2.12 release, -newer versions bore successively more restrictive licenses. This version -of OpenSSH -.Bl -bullet -.It -has all components of a restrictive nature (ie. patents, see -.Xr ssl 8 ) -directly removed from the source code; any licensed or patented components -are chosen from -external libraries. -.It -has been updated to support ssh protocol 1.5. -.It -contains added support for -.Xr kerberos 8 -authentication and ticket passing. -.It -supports one-time password authentication with -.Xr skey 1 . -.El -.Pp -The libraries described in -.Xr ssl 8 -are required for proper operation. -.Sh SEE ALSO -.Xr rlogin 1 , -.Xr rsh 1 , -.Xr scp 1 , -.Xr ssh 1 , -.Xr ssh-add 1 , -.Xr ssh-agent 1 , -.Xr ssh-keygen 1 , -.Xr ssl 8 |