[-h host_key_file] [-k key_gen_time] [-p port] [-u len]
DESCRIPTION
sshd (SSH Daemon) is the daemon program for ssh(1). Together these pro-
grams replace rlogin and rsh, 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.
sshd is the daemon that listens for connections from clients. It is nor-
mally started at boot from /etc/rc. It forks a new daemon for each
incoming connection. The forked daemons handle key exchange, encryption,
authentication, command execution, and data exchange. This implementa-
tion of sshd supports both SSH protocol version 1 and 2 simultaneously.
sshd works as follows.
SSH protocol version 1
Each host has a host-specific RSA key (normally 1024 bits) used to iden-
tify 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.
Whenever a client connects the daemon responds with its public host and
server keys. The client compares the RSA host key against its own data-
base 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 use this random number as a session key which is used to
encrypt all further communications in the session. The rest of the ses-
sion is encrypted using a conventional cipher, currently Blowfish or
3DES, with 3DES being used by default. The client selects the encryption
algorithm to use from those offered by the server.
Next, the server and the client enter an authentication dialog. The
client tries to authenticate itself using .rhosts authentication, .rhosts
authentication combined with RSA host authentication, RSA challenge-
response authentication, or password based authentication.
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 rshd(8), rlogind(8), and rexecd(8)
are disabled (thus completely disabling rlogin(1) and rsh(1) into the
machine).
SSH protocol version 2
Version 2 works similarly: Each host has a host-specific key (RSA or DSA)
used to identify the host. However, when the daemon starts, it does not
generate a server key. Forward security is provided through a Diffie-
Hellman key agreement. This key agreement results in a shared session
key.
The rest of the session is encrypted using a symmetric cipher, currently
128 bit AES, Blowfish, 3DES, CAST128, Arcfour, 192 bit AES, or 256 bit
connections, or forwarding the authentication agent connection over the
secure channel.
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.
When the user program terminates and all forwarded X11 and other connec-
tions have been closed, the server sends command exit status to the
client, and both sides exit.
sshd can be configured using command-line options or a configuration
file. Command-line options override values specified in the configura-
tion file.
sshd rereads its configuration file when it receives a hangup signal,
SIGHUP, by executing itself with the name it was started as, i.e.,
/usr/sbin/sshd.
The options are as follows:
-b bits
Specifies the number of bits in the ephemeral protocol version 1
server key (default 768).
-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. Multiple -d
options increase the debugging level. Maximum is 3.
-e When this option is specified, sshd will send the output to the
standard error instead of the system log.
-f configuration_file
Specifies the name of the configuration file. The default is
/etc/sshd_config. sshd refuses to start if there is no configu-
ration file.
-g login_grace_time
Gives the grace time for clients to authenticate themselves
(default 600 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.
-h host_key_file
Specifies the file from which the host key is read (default
/etc/ssh_host_key). This option must be given if sshd is not run
as root (as the normal host file is normally not readable by any-
one but root). It is possible to have multiple host key files
for the different protocol versions and host key algorithms.
if the machine is cracked into or physically seized. A value of
zero indicates that the key will never be regenerated.
-p port
Specifies the port on which the server listens for connections
(default 22).
-q Quiet mode. Nothing is sent to the system log. Normally the
beginning, authentication, and termination of each connection is
logged.
-t Test mode. Only check the validity of the configuration file and
sanity of the keys. This is useful for updating sshd reliably as
configuration options may change.
-u len This option is used to specify the size of the field in the utmp
structure that holds the remote host name. If the resolved host
name is longer than len, the dotted decimal value will be used
instead. This allows hosts with very long host names that over-
flow this field to still be uniquely identified. Specifying -u0
indicates that only dotted decimal addresses should be put into
the utmp file. -u0 is also be used to prevent sshd from making
DNS requests unless the authentication mechanism or configuration
requires it. Authentication mechanisms that may require DNS
include RhostsAuthentication, RhostsRSAAuthentication,
HostbasedAuthentication and using a from="pattern-list" option in
a key file.
-D When this option is specified sshd will not detach and does not
become a daemon. This allows easy monitoring of sshd.
-4 Forces sshd to use IPv4 addresses only.
-6 Forces sshd to use IPv6 addresses only.
CONFIGURATION FILE
sshd reads configuration data from /etc/sshd_config (or the file speci-
fied with -f on the command line). The file contains keyword-argument
pairs, one per line. Lines starting with `#' and empty lines are inter-
preted as comments.
The possible keywords and their meanings are as follows (note that key-
words are case-insensitive and arguments are case-sensitive):
AFSTokenPassing
Specifies whether an AFS token may be forwarded to the server.
Default is ``yes''.
AllowGroups
This keyword can be followed by a list of group names, separated
by spaces. If specified, login is allowed only for users whose
primary group or supplementary group list matches one of the pat-
wildcards in the patterns. Only user names are valid; a numeri-
cal user ID is not recognized. By default login is allowed
regardless of the user name. If the pattern takes the form
USER@HOST then USER and HOST are separately checked, restricting
logins to particular users from particular hosts.
AuthorizedKeysFile
Specifies the file that contains the public keys that can be used
for user authentication. AuthorizedKeysFile may contain tokens
of the form %T which are substituted during connection set-up.
The following tokens are defined: %% is replaced by a literal
'%', %h is replaced by the home directory of the user being
authenticated and %u is replaced by the username of that user.
After expansion, AuthorizedKeysFile is taken to be an absolute
path or one relative to the user's home directory. The default
is ``.ssh/authorized_keys''
Banner In some jurisdictions, sending a warning message before authenti-
cation may be relevant for getting legal protection. The con-
tents of the specified file are sent to the remote user before
authentication is allowed. This option is only available for
protocol version 2.
ChallengeResponseAuthentication
Specifies whether challenge response authentication is allowed.
All authentication styles from login.conf(5) are supported. The
default is ``yes''.
Ciphers
Specifies the ciphers allowed for protocol version 2. Multiple
ciphers must be comma-separated. The default is
``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour.''
ClientAliveInterval
Sets a timeout interval in seconds after which if no data has
been received from the client, sshd will send a message through
the encrypted channel to request a response from the client. The
default is 0, indicating that these messages will not be sent to
the client. This option applies to protocol version 2 only.
ClientAliveCountMax
Sets the number of client alive messages (see above) which may be
sent without sshd receiving any messages back from the client. If
this threshold is reached while client alive messages are being
sent, sshd will disconnect the client, terminating the session.
It is important to note that the use of client alive messages is
very different from KeepAlive (below). The client alive messages
are sent through the encrypted channel and therefore will not be
spoofable. The TCP keepalive option enabled by KeepAlive is
spoofable. The client alive mechanism is valuable when the client
or server depend on knowing when a connection has become inac-
tive.
This keyword can be followed by a number of user names, separated
by spaces. Login is disallowed for user names that match one of
the patterns. `*' and `'? can be used as wildcards in the pat-
terns. Only user names are valid; a numerical user ID is not
recognized. By default login is allowed regardless of the user
name.
GatewayPorts
Specifies whether remote hosts are allowed to connect to ports
forwarded for the client. By default, sshd binds remote port
forwardings to the loopback addresss. This prevents other remote
hosts from connecting to forwarded ports. GatewayPorts can be
used to specify that sshd should bind remote port forwardings to
the wildcard address, thus allowing remote hosts to connect to
forwarded ports. The argument must be ``yes'' or ``no''. The
default is ``no''.
HostbasedAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication
together with successful public key client host authentication is
allowed (hostbased authentication). This option is similar to
RhostsRSAAuthentication and applies to protocol version 2 only.
The default is ``no''.
HostKey
Specifies the file containing the private host keys (default
/etc/ssh_host_key) used by SSH protocol versions 1 and 2. Note
that sshd will refuse to use a file if it is group/world-accessi-
ble. It is possible to have multiple host key files. ``rsa1''
keys are used for version 1 and ``dsa'' or ``rsa'' are used for
version 2 of the SSH protocol.
IgnoreRhosts
Specifies that .rhosts and .shosts files will not be used in
RhostsAuthentication, RhostsRSAAuthentication or
HostbasedAuthentication.
/etc/hosts.equiv and /etc/shosts.equiv are still used. The
default is ``yes''.
IgnoreUserKnownHosts
Specifies whether sshd should ignore the user's
$HOME/.ssh/known_hosts during RhostsRSAAuthentication or
HostbasedAuthentication. The default is ``no''.
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 tempo-
rarily, and some people find it annoying. On the other hand, if
keepalives are not sent, sessions may hang indefinitely on the
Kerberos servtab which allows the verification of the KDC's iden-
tity. Default is ``yes''.
KerberosOrLocalPasswd
If set then if password authentication through Kerberos fails
then the password will be validated via any additional local
mechanism such as /etc/passwd. Default is ``yes''.
KerberosTgtPassing
Specifies whether a Kerberos TGT may be forwarded to the server.
Default is ``no'', as this only works when the Kerberos KDC is
actually an AFS kaserver.
KerberosTicketCleanup
Specifies whether to automatically destroy the user's ticket
cache file on logout. Default is ``yes''.
KeyRegenerationInterval
In protocol version 1, the ephemeral server key is automatically
regenerated after this many seconds (if it has been used). The
purpose of regeneration is to prevent decrypting captured ses-
sions 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).
ListenAddress
Specifies the local addresses sshd should listen on. The follow-
ing forms may be used:
ListenAddress host|IPv4_addr|IPv6_addr
ListenAddress host|IPv4_addr:port
ListenAddress [host|IPv6_addr]:port
If port is not specified, sshd will listen on the address and all
prior Port options specified. The default is to listen on all
local addresses. Multiple ListenAddress options are permitted.
Additionally, any Port options must precede this option for non
port qualified addresses.
LoginGraceTime
The server disconnects after this time if the user has not suc-
cessfully logged in. If the value is 0, there is no time limit.
The default is 600 (seconds).
LogLevel
Gives the verbosity level that is used when logging messages from
sshd. The possible values are: QUIET, FATAL, ERROR, INFO, VER-
BOSE and DEBUG. The default is INFO. Logging with level DEBUG
violates the privacy of users and is not recommended.
MACs Specifies the available MAC (message authentication code) algo-
rithms. The MAC algorithm is used in protocol version 2 for data
(10) unauthenticated connections. The probability increases lin-
early and all connection attempts are refused if the number of
unauthenticated connections reaches ``full'' (60).
PAMAuthenticationViaKbdInt
Specifies whether PAM challenge response authentication is
allowed. This allows the use of most PAM challenge response
authentication modules, but it will allow password authentication
regardless of whether PasswordAuthentication is disabled. The
default is ``no''.
PasswordAuthentication
Specifies whether password authentication is allowed. The
default is ``yes''.
PermitEmptyPasswords
When password authentication is allowed, it specifies whether the
server allows login to accounts with empty password strings. The
default is ``no''.
PermitRootLogin
Specifies whether root can login using ssh(1). The argument must
be ``yes'', ``without-password'', ``forced-commands-only'' or
``no''. The default is ``yes''.
If this option is set to ``without-password'' password authenti-
cation is disabled for root.
If this option is set to ``forced-commands-only'' root login with
public key authentication will be allowed, but only if the
command option has been specified (which may be useful for taking
remote backups even if root login is normally not allowed). All
other authentication methods are disabled for root.
If this option is set to ``no'' root is not allowed to login.
PidFile
Specifies the file that contains the process identifier of the
sshd daemon. The default is /var/run/sshd.pid.
Port Specifies the port number that sshd listens on. The default is
22. Multiple options of this type are permitted. See also
ListenAddress.
PrintLastLog
Specifies whether sshd should print the date and time when the
user last logged in. The default is ``yes''.
PrintMotd
Specifies whether sshd should print /etc/motd when a user logs in
interactively. (On some systems it is also printed by the shell,
/etc/profile, or equivalent.) The default is ``yes''.
maps back to the very same IP address. The default is ``no''.
RhostsAuthentication
Specifies whether authentication using rhosts or /etc/hosts.equiv
files is sufficient. Normally, this method should not be permit-
ted because it is insecure. 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 ``no''. This option applies to protocol version 1
only.
RhostsRSAAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication
together with successful RSA host authentication is allowed. The
default is ``no''. This option applies to protocol version 1
only.
RSAAuthentication
Specifies whether pure RSA authentication is allowed. The
default is ``yes''. This option applies to protocol version 1
only.
ServerKeyBits
Defines the number of bits in the ephemeral protocol version 1
server key. The minimum value is 512, and the default is 768.
StrictModes
Specifies whether sshd 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
``yes''.
Subsystem
Configures an external subsystem (e.g., file transfer daemon).
Arguments should be a subsystem name and a command to execute
upon subsystem request. The command sftp-server(8) implements
the ``sftp'' file transfer subsystem. By default no subsystems
are defined. Note that this option applies to protocol version 2
only.
SyslogFacility
Gives the facility code that is used when logging messages from
sshd. The possible values are: DAEMON, USER, AUTH, LOCAL0,
LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. The
default is AUTH.
UseLogin
Specifies whether login(1) is used for interactive login ses-
sions. The default is ``no''. Note that login(1) is never used
for remote command execution. Note also, that if this is
enabled, X11Forwarding will be disabled because login(1) does not
XAuthLocation
Specifies the location of the xauth(1) program. The default is
/usr/X11R6/bin/xauth.
Time Formats
sshd command-line arguments and configuration file options that specify
time may be expressed using a sequence of the form: time[qualifier],
where time is a positive integer value and qualifier is one of the fol-
lowing:
<none> seconds
s | S seconds
m | M minutes
h | H hours
d | D days
w | W weeks
Each member of the sequence is added together to calculate the total time
value.
Time format examples:
600 600 seconds (10 minutes)
10m 10 minutes
1h30m 1 hour 30 minutes (90 minutes)
LOGIN PROCESS
When a user successfully logs in, sshd does the following:
1. If the login is on a tty, and no command has been specified,
prints last login time and /etc/motd (unless prevented in the
configuration file or by $HOME/.hushlogin; see the FILES sec-
tion).
2. If the login is on a tty, records login time.
3. Checks /etc/nologin; if it exists, prints contents and quits
(unless root).
4. Changes to run with normal user privileges.
5. Sets up basic environment.
6. Reads $HOME/.ssh/environment if it exists.
7. Changes to user's home directory.
8. If $HOME/.ssh/rc exists, runs it; else if /etc/sshrc exists,
runs it; otherwise runs xauth. The ``rc'' files are given the
X11 authentication protocol and cookie in standard input.
9. Runs user's shell or command.
lus and comment fields give the RSA key for protocol version 1; the com-
ment field is not used for anything (but may be convenient for the user
to identify the key). For protocol version 2 the keytype is ``ssh-dss''
or ``ssh-rsa''.
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 identity.pub, id_dsa.pub or the id_rsa.pub
file and edit it.
The options (if present) consist of comma-separated option specifica-
tions. No spaces are permitted, except within double quotes. The fol-
lowing option specifications are supported (note that option keywords are
case-insensitive):
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).
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 client requests a
pty; otherwise it is run without a tty. If a 8-bit clean channel
is required, one must not request a pty or should specify no-pty.
A quote may be included in the command by quoting it with a back-
slash. 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. Note that the
client may specify TCP/IP and/or X11 forwarding unless they are
explicitly prohibited. Note that this option applies to shell,
command or subsystem execution.
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. This option is automatically disabled
if UseLogin is enabled.
no-port-forwarding
Forbids TCP/IP forwarding when this key is used for authentica-
permitopen="host:port"
Limit local ``ssh -L'' port forwarding such that it may only con-
nect to the specified host and port. IPv6 addresses can be spec-
ified with an alternative syntax: host/port. Multiple permitopen
options may be applied separated by commas. No pattern matching
is performed on the specified hostnames, they must be literal
domains or addresses.
Examples
1024 33 12121...312314325 ylo@foo.bar
from="*.niksula.hut.fi,!pc.niksula.hut.fi" 1024 35 23...2334 ylo@niksula
command="dump /home",no-pty,no-port-forwarding 1024 33 23...2323
backup.hut.fi
permitopen="10.2.1.55:80",permitopen="10.2.1.56:25" 1024 33 23...2323
SSH_KNOWN_HOSTS FILE FORMAT
The /etc/ssh_known_hosts, and $HOME/.ssh/known_hosts files contain host
public keys for all known hosts. The global file should be prepared by
the administrator (optional), and the per-user file is maintained auto-
matically: whenever the user connects from an unknown host its key is
added to the per-user file.
Each line in these files contains the following fields: hostnames, bits,
exponent, modulus, comment. The fields are separated by spaces.
Hostnames is a comma-separated list of patterns ('*' and '?' act as wild-
cards); 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 `'! 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.
Bits, exponent, and modulus are taken directly from the RSA host key;
they can be obtained, e.g., from /etc/ssh_host_key.pub. The optional
comment field continues to the end of the line, and is not used.
Lines starting with `#' and empty lines are ignored as comments.
When performing host authentication, authentication is accepted if any
matching line has the proper key. It is thus permissible (but not recom-
mended) 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 con-
flicting information; authentication is accepted if valid information can
be found from either file.
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 /etc/ssh_host_key.pub and
These files should only be owned by root, readable only by root,
and not accessible to others. Note that sshd does not start if
this file is group/world-accessible.
/etc/ssh_host_key.pub, /etc/ssh_host_dsa_key.pub,
/etc/ssh_host_rsa_key.pub
These three files contain the public parts of the host keys.
These files should be world-readable but writable only by root.
Their contents should match the respective private parts. These
files are not really used for anything; they are provided for the
convenience of the user so their contents can be copied to known
hosts files. These files are created using ssh-keygen(1).
/etc/moduli
Contains Diffie-Hellman groups used for the "Diffie-Hellman Group
Exchange".
/var/run/sshd.pid
Contains the process ID of the sshd listening for connections (if
there are several daemons running concurrently for different
ports, this contains the pid of the one started last). The con-
tent of this file is not sensitive; it can be world-readable.
$HOME/.ssh/authorized_keys
Lists the public keys (RSA or DSA) 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. Users will place the contents of their
identity.pub, id_dsa.pub and/or id_rsa.pub files into this file,
as described in ssh-keygen(1).
/etc/ssh_known_hosts and $HOME/.ssh/known_hosts
These files are consulted when using rhosts with RSA host authen-
tication or protocol version 2 hostbased authentication to check
the public key of the host. The key must be listed in one of
these files to be accepted. The client uses the same files to
verify that it is connecting to the correct remote host. These
files should be writable only by root/the owner.
/etc/ssh_known_hosts should be world-readable, and
$HOME/.ssh/known_hosts can but need not be world-readable.
/etc/nologin
If this file exists, sshd 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.
/etc/hosts.allow, /etc/hosts.deny
Access controls that should be enforced by tcp-wrappers are
defined here. Further details are described in hosts_access(5).
this file is not used by rlogin and rshd, so using this permits
access using SSH only.
/etc/hosts.equiv
This file is used during .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 any user on this machine (except root). Additionally, the
syntax ``+@group'' can be used to specify netgroups. Negated
entries start with `-'.
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.
Warning: It is almost never a good idea to use user names in
hosts.equiv. Beware that it really means that the named user(s)
can log in as 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.
Note that this warning also applies to rsh/rlogin.
/etc/shosts.equiv
This is processed exactly as /etc/hosts.equiv. However, this
file may be useful in environments that want to run both
rsh/rlogin and ssh.
$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
`#'), 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.
$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 com-
mand. If X11 spoofing is in use, this will receive the "proto
cookie" pair in standard input (and DISPLAY in environment).
This must call xauth(1) in that case.
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 envi-
ronment.
/etc/sshrc
Like $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.
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 cre-
ated OpenSSH. Markus Friedl contributed the support for SSH protocol
versions 1.5 and 2.0.
SEE ALSO
scp(1), sftp(1), ssh(1), ssh-add(1), ssh-agent(1), ssh-keygen(1),
login.conf(5), moduli(5), sftp-server(8)
T. Ylonen, T. Kivinen, M. Saarinen, T. Rinne, and S. Lehtinen, SSH
Protocol Architecture, draft-ietf-secsh-architecture-09.txt, July 2001,
work in progress material.
M. Friedl, N. Provos, and W. A. Simpson, Diffie-Hellman Group Exchange
for the SSH Transport Layer Protocol, draft-ietf-secsh-dh-group-
exchange-01.txt, April 2001, work in progress material.
BSD September 25, 1999 BSD
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