NTP_KEYGEN(8) | System Manager's Manual (user) | NTP_KEYGEN(8) |
ntp-keygen
—
ntp-keygen |
[-flags ] [-flag
[value]] [--option-name [[=|
]value]]
All arguments must be options. |
All files are in PEM-encoded printable ASCII format, so they can be embedded as MIME attachments in mail to other sites and certificate authorities. By default, files are not encrypted.
When used to generate message digest keys, the program produces a file containing ten pseudo-random printable ASCII strings suitable for the MD5 message digest algorithm included in the distribution. If the OpenSSL library is installed, it produces an additional ten hex-encoded random bit strings suitable for the SHA1 and other message digest algorithms. The message digest keys file must be distributed and stored using secure means beyond the scope of NTP itself. Besides the keys used for ordinary NTP associations, additional keys can be defined as passwords for the ntpq(8) and ntpdc(8) utility programs.
The remaining generated files are compatible with other OpenSSL applications and other Public Key Infrastructure (PKI) resources. Certificates generated by this program are compatible with extant industry practice, although some users might find the interpretation of X509v3 extension fields somewhat liberal. However, the identity keys are probably not compatible with anything other than Autokey.
Some files used by this program are encrypted using a private
password. The -p
option specifies the password for
local encrypted files and the -q
option the password
for encrypted files sent to remote sites. If no password is specified, the
host name returned by the Unix gethostname
()
function, normally the DNS name of the host is used.
The pw option of the crypto configuration command specifies the read password for previously encrypted local files. This must match the local password used by this program. If not specified, the host name is used. Thus, if files are generated by this program without password, they can be read back by ntpd without password but only on the same host.
Normally, encrypted files for each host are generated by that host and used only by that host, although exceptions exist as noted later on this page. The symmetric keys file, normally called ntp.keys, is usually installed in /etc. Other files and links are usually installed in /usr/local/etc, which is normally in a shared filesystem in NFS-mounted networks and cannot be changed by shared clients. The location of the keys directory can be changed by the keysdir configuration command in such cases. Normally, this is in /etc.
This program directs commentary and error messages to the standard error stream stderr and remote files to the standard output stream stdout where they can be piped to other applications or redirected to files. The names used for generated files and links all begin with the string ntpkey and include the file type, generating host and filestamp, as described in the “Cryptographic Data Files” section below.
ntp-keygen
command without arguments to generate a
default RSA host key and matching RSA-MD5 certificate with expiration date one
year hence. If run again without options, the program uses the existing keys
and parameters and generates only a new certificate with new expiration date
one year hence.
Run the command on as many hosts as necessary. Designate one of
them as the trusted host (TH) using ntp-keygen
with
the -T
option and configure it to synchronize from
reliable Internet servers. Then configure the other hosts to synchronize to
the TH directly or indirectly. A certificate trail is created when Autokey
asks the immediately ascendant host towards the TH to sign its certificate,
which is then provided to the immediately descendant host on request. All
group hosts should have acyclic certificate trails ending on the TH.
The host key is used to encrypt the cookie when required and so
must be RSA type. By default, the host key is also the sign key used to
encrypt signatures. A different sign key can be assigned using the
-S
option and this can be either RSA or DSA type. By
default, the signature message digest type is MD5, but any combination of
sign key type and message digest type supported by the OpenSSL library can
be specified using the -c
option. The rules say
cryptographic media should be generated with proventic filestamps, which
means the host should already be synchronized before this program is run.
This of course creates a chicken-and-egg problem when the host is started
for the first time. Accordingly, the host time should be set by some other
means, such as eyeball-and-wristwatch, at least so that the certificate
lifetime is within the current year. After that and when the host is
synchronized to a proventic source, the certificate should be
re-generated.
Additional information on trusted groups and identity schemes is on the “Autokey Public-Key Authentication” page.
The ntpd(8)
configuration command crypto pw
password specifies the read password for previously
encrypted files. The daemon expires on the spot if the password is missing
or incorrect. For convenience, if a file has been previously encrypted, the
default read password is the name of the host running the program. If the
previous write password is specified as the host name, these files can be
read by that host with no explicit password.
File names begin with the prefix ntpkey_
and end with the postfix _hostname.filestamp, where
hostname is the owner name, usually the string
returned by the Unix gethostname() routine, and
filestamp is the NTP seconds when the file was
generated, in decimal digits. This both guarantees uniqueness and simplifies
maintenance procedures, since all files can be quickly removed by a
rm ntpkey*
command or all files generated at a
specific time can be removed by a rm
*filestamp command. To further reduce the risk of
misconfiguration, the first two lines of a file contain the file name and
generation date and time as comments.
All files are installed by default in the keys directory /usr/local/etc, which is normally in a shared filesystem in NFS-mounted networks. The actual location of the keys directory and each file can be overridden by configuration commands, but this is not recommended. Normally, the files for each host are generated by that host and used only by that host, although exceptions exist as noted later on this page.
Normally, files containing private values, including the host key, sign key and identification parameters, are permitted root read/write-only; while others containing public values are permitted world readable. Alternatively, files containing private values can be encrypted and these files permitted world readable, which simplifies maintenance in shared file systems. Since uniqueness is insured by the hostname and file name extensions, the files for a NFS server and dependent clients can all be installed in the same shared directory.
The recommended practice is to keep the file name extensions when
installing a file and to install a soft link from the generic names
specified elsewhere on this page to the generated files. This allows new
file generations to be activated simply by changing the link. If a link is
present, ntpd follows it to the file name to extract the filestamp. If a
link is not present, ntpd(8)
extracts the filestamp from the file itself. This allows clients to verify
that the file and generation times are always current. The
ntp-keygen
program uses the same timestamp extension
for all files generated at one time, so each generation is distinct and can
be readily recognized in monitoring data.
ntp-keygen
program is logged
in directly as root. The recommended procedure is change to the keys
directory, usually /usr/local/etc, then run the
program. When run for the first time, or if all ntpkey
files have been removed, the program generates a RSA host key file and
matching RSA-MD5 certificate file, which is all that is necessary in many
cases. The program also generates soft links from the generic names to the
respective files. If run again, the program uses the same host key file, but
generates a new certificate file and link.
The host key is used to encrypt the cookie when required and so must be RSA type. By default, the host key is also the sign key used to encrypt signatures. When necessary, a different sign key can be specified and this can be either RSA or DSA type. By default, the message digest type is MD5, but any combination of sign key type and message digest type supported by the OpenSSL library can be specified, including those using the MD2, MD5, SHA, SHA1, MDC2 and RIPE160 message digest algorithms. However, the scheme specified in the certificate must be compatible with the sign key. Certificates using any digest algorithm are compatible with RSA sign keys; however, only SHA and SHA1 certificates are compatible with DSA sign keys.
Private/public key files and certificates are compatible with other OpenSSL applications and very likely other libraries as well. Certificates or certificate requests derived from them should be compatible with extant industry practice, although some users might find the interpretation of X509v3 extension fields somewhat liberal. However, the identification parameter files, although encoded as the other files, are probably not compatible with anything other than Autokey.
Running the program as other than root and using the Unix
su
command to assume root may not work properly,
since by default the OpenSSL library looks for the random seed file
.rnd
in the user home directory. However, there
should be only one .rnd
, most conveniently in the
root directory, so it is convenient to define the
$RANDFILE
environment variable used by the OpenSSL
library as the path to /.rnd
.
Installing the keys as root might not work in NFS-mounted shared
file systems, as NFS clients may not be able to write to the shared keys
directory, even as root. In this case, NFS clients can specify the files in
another directory such as /etc using the
keysdir
command. There is no need for one client to
read the keys and certificates of other clients or servers, as these data
are obtained automatically by the Autokey protocol.
Ordinarily, cryptographic files are generated by the host that uses them, but it is possible for a trusted agent (TA) to generate these files for other hosts; however, in such cases files should always be encrypted. The subject name and trusted name default to the hostname of the host generating the files, but can be changed by command line options. It is convenient to designate the owner name and trusted name as the subject and issuer fields, respectively, of the certificate. The owner name is also used for the host and sign key files, while the trusted name is used for the identity files.
All files are installed by default in the keys directory /usr/local/etc, which is normally in a shared filesystem in NFS-mounted networks. The actual location of the keys directory and each file can be overridden by configuration commands, but this is not recommended. Normally, the files for each host are generated by that host and used only by that host, although exceptions exist as noted later on this page.
Normally, files containing private values, including the host key, sign key and identification parameters, are permitted root read/write-only; while others containing public values are permitted world readable. Alternatively, files containing private values can be encrypted and these files permitted world readable, which simplifies maintenance in shared file systems. Since uniqueness is insured by the hostname and file name extensions, the files for a NFS server and dependent clients can all be installed in the same shared directory.
The recommended practice is to keep the file name extensions when
installing a file and to install a soft link from the generic names
specified elsewhere on this page to the generated files. This allows new
file generations to be activated simply by changing the link. If a link is
present, ntpd follows it to the file name to extract the filestamp. If a
link is not present, ntpd(8)
extracts the filestamp from the file itself. This allows clients to verify
that the file and generation times are always current. The
ntp-keygen
program uses the same timestamp extension
for all files generated at one time, so each generation is distinct and can
be readily recognized in monitoring data.
ntp-keygen
program is logged
in directly as root. The recommended procedure is change to the keys
directory, usually /usr/local/etc, then run the
program. When run for the first time, or if all ntpkey
files have been removed, the program generates a RSA host key file and
matching RSA-MD5 certificate file, which is all that is necessary in many
cases. The program also generates soft links from the generic names to the
respective files. If run again, the program uses the same host key file, but
generates a new certificate file and link.
The host key is used to encrypt the cookie when required and so must be RSA type. By default, the host key is also the sign key used to encrypt signatures. When necessary, a different sign key can be specified and this can be either RSA or DSA type. By default, the message digest type is MD5, but any combination of sign key type and message digest type supported by the OpenSSL library can be specified, including those using the MD2, MD5, SHA, SHA1, MDC2 and RIPE160 message digest algorithms. However, the scheme specified in the certificate must be compatible with the sign key. Certificates using any digest algorithm are compatible with RSA sign keys; however, only SHA and SHA1 certificates are compatible with DSA sign keys.
Private/public key files and certificates are compatible with other OpenSSL applications and very likely other libraries as well. Certificates or certificate requests derived from them should be compatible with extant industry practice, although some users might find the interpretation of X509v3 extension fields somewhat liberal. However, the identification parameter files, although encoded as the other files, are probably not compatible with anything other than Autokey.
Running the program as other than root and using the Unix
su
command to assume root may not work properly,
since by default the OpenSSL library looks for the random seed file
.rnd
in the user home directory. However, there
should be only one .rnd
, most conveniently in the
root directory, so it is convenient to define the
$RANDFILE
environment variable used by the OpenSSL
library as the path to /.rnd
.
Installing the keys as root might not work in NFS-mounted shared
file systems, as NFS clients may not be able to write to the shared keys
directory, even as root. In this case, NFS clients can specify the files in
another directory such as /etc using the
keysdir
command. There is no need for one client to
read the keys and certificates of other clients or servers, as these data
are obtained automatically by the Autokey protocol.
Ordinarily, cryptographic files are generated by the host that uses them, but it is possible for a trusted agent (TA) to generate these files for other hosts; however, in such cases files should always be encrypted. The subject name and trusted name default to the hostname of the host generating the files, but can be changed by command line options. It is convenient to designate the owner name and trusted name as the subject and issuer fields, respectively, of the certificate. The owner name is also used for the host and sign key files, while the trusted name is used for the identity files. seconds. seconds. s Trusted Hosts and Groups Each cryptographic configuration involves selection of a signature scheme and identification scheme, called a cryptotype, as explained in the Authentication Options section of ntp.conf(5). The default cryptotype uses RSA encryption, MD5 message digest and TC identification. First, configure a NTP subnet including one or more low-stratum trusted hosts from which all other hosts derive synchronization directly or indirectly. Trusted hosts have trusted certificates; all other hosts have nontrusted certificates. These hosts will automatically and dynamically build authoritative certificate trails to one or more trusted hosts. A trusted group is the set of all hosts that have, directly or indirectly, a certificate trail ending at a trusted host. The trail is defined by static configuration file entries or dynamic means described on the Automatic NTP Configuration Options section of ntp.conf(5).
On each trusted host as root, change to the keys directory. To
insure a fresh fileset, remove all ntpkey
files.
Then run ntp-keygen
-T
to
generate keys and a trusted certificate. On all other hosts do the same, but
leave off the -T
flag to generate keys and
nontrusted certificates. When complete, start the NTP daemons beginning at
the lowest stratum and working up the tree. It may take some time for
Autokey to instantiate the certificate trails throughout the subnet, but
setting up the environment is completely automatic.
If it is necessary to use a different sign key or different
digest/signature scheme than the default, run
ntp-keygen
with the -S
type option, where type is
either RSA
or DSA
. The most
often need to do this is when a DSA-signed certificate is used. If it is
necessary to use a different certificate scheme than the default, run
ntp-keygen
with the -c
scheme option and selected
scheme as needed. f ntp-keygen
is run again without these options, it generates a new certificate using the
same scheme and sign key.
After setting up the environment it is advisable to update
certificates from time to time, if only to extend the validity interval.
Simply run ntp-keygen
with the same flags as before
to generate new certificates using existing keys. However, if the host or
sign key is changed, ntpd(8)
should be restarted. When
ntpd(8) is restarted, it loads
any new files and restarts the protocol. Other dependent hosts will continue
as usual until signatures are refreshed, at which time the protocol is
restarted.
http://www.eecis.udel.edu/%7emills/keygen.html
). These
schemes are based on a TA, one or more trusted hosts and some number of
nontrusted hosts. Trusted hosts prove identity using values provided by the
TA, while the remaining hosts prove identity using values provided by a
trusted host and certificate trails that end on that host. The name of a
trusted host is also the name of its sugroup and also the subject and issuer
name on its trusted certificate. The TA is not necessarily a trusted host in
this sense, but often is.
In some schemes there are separate keys for servers and clients. A server can also be a client of another server, but a client can never be a server for another client. In general, trusted hosts and nontrusted hosts that operate as both server and client have parameter files that contain both server and client keys. Hosts that operate only as clients have key files that contain only client keys.
The PC scheme supports only one trusted host in the group. On
trusted host alice run ntp-keygen
-P
-p
password to generate the host key file
ntpkey_RSAkey_alice.filestamp
and trusted private certificate file
ntpkey_RSA-MD5_cert_alice.filestamp.
Copy both files to all group hosts; they replace the files which would be
generated in other schemes. On each host bob install a soft link from the
generic name ntpkey_host_bob
to the host key file and soft link
ntpkey_cert_bob to the private
certificate file. Note the generic links are on bob, but point to files
generated by trusted host alice. In this scheme it is not possible to
refresh either the keys or certificates without copying them to all other
hosts in the group.
For the IFF scheme proceed as in the TC scheme to generate keys
and certificates for all group hosts, then for every trusted host in the
group, generate the IFF parameter file. On trusted host alice run
ntp-keygen
-T
-I
-p
password to produce her parameter file
ntpkey_IFFpar_alice.filestamp,
which includes both server and client keys. Copy this file to all group
hosts that operate as both servers and clients and install a soft link from
the generic ntpkey_iff_alice
to this file. If there are no hosts restricted to operate only as clients,
there is nothing further to do. As the IFF scheme is independent of keys and
certificates, these files can be refreshed as needed.
If a rogue client has the parameter file, it could masquerade as a
legitimate server and present a middleman threat. To eliminate this threat,
the client keys can be extracted from the parameter file and distributed to
all restricted clients. After generating the parameter file, on alice run
ntp-keygen
-e
and pipe the
output to a file or mail program. Copy or mail this file to all restricted
clients. On these clients install a soft link from the generic
ntpkey_iff_alice to this file.
To further protect the integrity of the keys, each file can be encrypted
with a secret password.
For the GQ scheme proceed as in the TC scheme to generate keys and
certificates for all group hosts, then for every trusted host in the group,
generate the IFF parameter file. On trusted host alice run
ntp-keygen
-T
-G
-p
password to produce her parameter file
ntpkey_GQpar_alice.filestamp,
which includes both server and client keys. Copy this file to all group
hosts and install a soft link from the generic
ntpkey_gq_alice to this file.
In addition, on each host bob install a soft link from generic
ntpkey_gq_bob to this file. As
the GQ scheme updates the GQ parameters file and certificate at the same
time, keys and certificates can be regenerated as needed.
For the MV scheme, proceed as in the TC scheme to generate keys
and certificates for all group hosts. For illustration assume trish is the
TA, alice one of several trusted hosts and bob one of her clients. On TA
trish run ntp-keygen
-V
n -p
password, where n is the number
of revokable keys (typically 5) to produce the parameter file
ntpkeys_MVpar_trish.filestamp
and client key files
ntpkeys_MVkeyd_trish.filestamp
where d is the key number (0 <
d < n). Copy the parameter
file to alice and install a soft link from the generic
ntpkey_mv_alice to this file.
Copy one of the client key files to alice for later distribution to her
clients. It doesn't matter which client key file goes to alice, since they
all work the same way. Alice copies the client key file to all of her
cliens. On client bob install a soft link from generic
ntpkey_mvkey_bob to the client
key file. As the MV scheme is independent of keys and certificates, these
files can be refreshed as needed.
-c
schemeRSA-MD2
, RSA-MD5
,
RSA-SHA
, RSA-SHA1
,
RSA-MDC2
, RSA-RIPEMD160
,
DSA-SHA
, or DSA-SHA1
. Note
that RSA schemes must be used with a RSA sign key and DSA schemes must be
used with a DSA sign key. The default without this option is
RSA-MD5
.-d
-e
-G
-g
-H
-I
-i
name-M
-P
-p
password-q
-S
[RSA
| DSA
]-s
name-T
-V
nkeysntp-keygen
program. If a site
supports OpenSSL or its companion OpenSSH, it is very likely that means to do
this are already available.
It is important to understand that entropy must be evolved for each generation, for otherwise the random number sequence would be predictable. Various means dependent on external events, such as keystroke intervals, can be used to do this and some systems have built-in entropy sources. Suitable means are described in the OpenSSL software documentation, but are outside the scope of this page.
The entropy seed used by the OpenSSL library is contained in a
file, usually called .rnd
, which must be available
when starting the NTP daemon or the ntp-keygen
program. The NTP daemon will first look for the file using the path
specified by the randfile
subcommand of the
crypto
configuration command. If not specified in
this way, or when starting the ntp-keygen
program,
the OpenSSL library will look for the file using the path specified by the
RANDFILE
environment variable in the user home
directory, whether root or some other user. If the
RANDFILE
environment variable is not present, the
library will look for the .rnd
file in the user home
directory. If the file is not available or cannot be written, the daemon
exits with a message to the system log and the program exits with a suitable
error message.
ntp-keygen
program and ntpd(8) daemon.
Cryptographic values are encoded first using ASN.1 rules, then encrypted if
necessary, and finally written PEM-encoded printable ASCII format preceded and
followed by MIME content identifier lines.
The format of the symmetric keys file is somewhat different than the other files in the interest of backward compatibility. Since DES-CBC is deprecated in NTPv4, the only key format of interest is MD5 alphanumeric strings. Following hte heard the keys are entered one per line in the format
#
’ character.
Note that the keys used by the ntpq(8) and ntpdc(8) programs are checked against passwords requested by the programs and entered by hand, so it is generally appropriate to specify these keys in human readable ASCII format.
The ntp-keygen
program generates a MD5
symmetric keys file
ntpkey_MD5key_hostname.filestamp.
Since the file contains private shared keys, it should be visible only to
root and distributed by secure means to other subnet hosts. The NTP daemon
loads the file ntp.keys, so
ntp-keygen
installs a soft link from this name to
the generated file. Subsequently, similar soft links must be installed by
manual or automated means on the other subnet hosts. While this file is not
used with the Autokey Version 2 protocol, it is needed to authenticate some
remote configuration commands used by the
ntpq(8) and
ntpdc(8) utilities.
-b
imbits,
--imbits
=imbitsin the range 256 through 2048
The number of bits in the identity modulus. The default is 256.
-c
scheme,
--certificate
=schemescheme is one of RSA-MD2, RSA-MD5, RSA-SHA, RSA-SHA1, RSA-MDC2, RSA-RIPEMD160, DSA-SHA, or DSA-SHA1.
Select the certificate message digest/signature encryption scheme. Note that RSA schemes must be used with a RSA sign key and DSA schemes must be used with a DSA sign key. The default without this option is RSA-MD5.
-C
cipher,
--cipher
=cipherSelect the cipher which is used to encrypt the files containing private keys. The default is three-key triple DES in CBC mode, equivalent to "@code{-C des-ede3-cbc". The openssl tool lists ciphers available in "openssl -h" output.
-d
,
--debug-level
-D
number,
--set-debug-level
=number-e
,
--id-key
Write the IFF or GQ client keys to the standard output. This is intended for automatic key distribution by mail.
-G
,
--gq-params
Generate parameters and keys for the GQ identification scheme, obsoleting any that may exist.
-H
,
--host-key
Generate new host keys, obsoleting any that may exist.
-I
,
--iffkey
Generate parameters for the IFF identification scheme, obsoleting any that may exist.
-i
group,
--ident
=groupSet the optional Autokey group name to name. This is used in the file name of IFF, GQ, and MV client parameters files. In that role, the default is the host name if this option is not provided. The group name, if specified using -i/--ident or using -s/--subject-name following an '@' character, is also a part of the self-signed host certificate's subject and issuer names in the form host@group and should match the ´crypto ident' or 'server ident' configuration in ntpd's configuration file.
-l
lifetime,
--lifetime
=lifetimeSet the certificate expiration to lifetime days from now.
-M
,
--md5key
Generate MD5 keys, obsoleting any that may exist.
-m
modulus,
--modulus
=modulusin the range 256 through 2048
The number of bits in the prime modulus. The default is 512.
-P
,
--pvt-cert
Generate a private certificate. By default, the program generates public certificates.
-p
passwd,
--pvt-passwd
=passwdEncrypt generated files containing private data with the specified password and the cipher selected with -C/--cipher.
-q
passwd,
--get-pvt-passwd
=passwdSet the password for reading files to the specified password.
-S
sign,
--sign-key
=signGenerate a new sign key of the designated type, obsoleting any that may exist. By default, the program uses the host key as the sign key.
-s
host@group,
--subject-name
=host@groupSet the Autokey host name, and optionally, group name specified following an '@' character. The host name is used in the file name of generated host and signing certificates, without the group name. The host name, and if provided, group name are used in host@group form for the host certificate's subject and issuer fields. Specifying '-s @group' is allowed, and results in leaving the host name unchanged while appending @group to the subject and issuer fields, as with -i group. The group name, or if not provided, the host name are also used in the file names of IFF, GQ, and MV client parameter files.
-T
,
--trusted-cert
Generate a trusted certificate. By default, the program generates a non-trusted certificate.
-V
num,
--mv-params
=numGenerate parameters and keys for the Mu-Varadharajan (MV) identification scheme.
-v
num,
--mv-keys
=numThis option has not been fully documented.
-?
,
--help
-!
,
--more-help
->
[cfgfile], --save-opts
[=cfgfile]-<
cfgfile,
--load-opts
=cfgfile,
--no-load-opts
--version
[{v|c|n}]NTP_KEYGEN_<option-name> or NTP_KEYGENThe environmental presets take precedence (are processed later than) the configuration files. The homerc files are "$HOME", and ".". If any of these are directories, then the file .ntprc is searched for within those directories. cvt_prog='/usr/local/gnu/share/autogen/texi2mdoc' cvt_prog=`cd `dirname "$cvt_prog"` >/dev/null && pwd
-p
password option specifies
the write password and -q
password option the read password for previously
encrypted files. The ntp-keygen
program prompts for
the password if it reads an encrypted file and the password is missing or
incorrect. If an encrypted file is read successfully and no write password is
specified, the read password is used as the write password by default.
Please report bugs to http://bugs.ntp.org .
Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org
This manual page was AutoGen-erated from the ntp-keygen option definitions.
December 24 2013 | SunOS 5.10 |