x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
ntp-keygen(1) User Commands ntp-keygen(1)
NAME
ntp-keygen - Create a NTP host key
SYNOPSIS
ntp-keygen [-flags] [-flag [value]] [--option-name[[=| ]value]]
All arguments must be options.
DESCRIPTION
This program generates cryptographic data files used by the NTPv4
authentication and identification schemes. It can generate message
digest keys used in symmetric key cryptography and, if the OpenSSL
software library has been installed, it can generate host keys, signing
keys, certificates, and identity keys and parameters used in Autokey
public key cryptography. These files are used for cookie encryption,
digital signature, and challenge/response identification algorithms
compatible with the Internet standard security infrastructure.
The message digest symmetric keys file is generated in a format compat-
ible with NTPv3. All other files are in PEM-encoded printable ASCII
format, so they can be embedded as MIME attachments in email to other
sites and certificate authorities. By default, files are not
encrypted.
When used to generate message digest symmetric keys, the program pro-
duces a file containing ten pseudo-random printable ASCII strings suit-
able 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 SHA1, AES-128-CMAC, and other
message digest algorithms. The message digest symmetric keys file must
be distributed and stored using secure means beyond the scope of NTP
itself. Besides the keys used for ordinary NTP associations, addi-
tional keys can be defined as passwords for the ntpq(1) and ntpdc(1)
utility programs.
The remaining generated files are compatible with other OpenSSL appli-
cations and other Public Key Infrastructure (PKI) resources. Certifi-
cates 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 read password for local encrypted files and
the -q option the write password for encrypted files sent to remote
sites. If no password is specified, the host name returned by the Unix
hostname(1) command, normally the DNS name of the host, is used as the
the default read password, for convenience. 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.
The pw option of the crypto ntpd(1) configuration command specifies the
read password for previously encrypted local files. This must match
the local read password used by this program. If not specified, the
host name is used. Thus, if files are generated by this program with-
out an explicit password, they can be read back by ntpd(1) without
specifying an explicit password but only on the same host. If the
write password used for encryption is specified as the host name, these
files can be read by that host with no explicit password.
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 usu-
ally 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. In these cases, NFS
clients can specify the files in another directory such as /etc using
the keysdir ntpd(1) configuration file command.
This program directs commentary and error messages to the standard
error stream stderr and remote files to the standard output stream std-
out 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.
Running the Program
The safest way to run the ntp-keygen program is logged in directly as
root. The recommended procedure is change to the keys directory, usu-
ally /usr/local/etc, then run the program.
To test and gain experience with Autokey concepts, log in as root and
change to the keys directory, usually /usr/local/etc. When run for the
first time, or if all files with names beginning with ntpkey* have been
removed, use the ntp-keygen command without arguments to generate a
default RSA host key and matching RSA-MD5 certificate file with expira-
tion date one year hence, 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 without options, the program uses the
existing keys and parameters and generates a new certificate file with
new expiration date one year hence, and soft 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 speci-
fied 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, includ-
ing those using the AES128CMAC, MD2, MD5, MDC2, SHA, SHA1 and RIPE160
message digest algorithms. However, the scheme specified in the cer-
tificate 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. Certifi-
cates 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(1) 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 vari-
able 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 ntpd(1) con-
figuration file 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
filestamp file name extensions, the files for an NTP server and depen-
dent 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(1) follows it to the file name to extract the
filestamp. If a link is not present, ntpd(1) 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 filestamp extension for all files generated at one time, so each
generation is distinct and can be readily recognized in monitoring
data.
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 con-
figure it to synchronize from reliable Internet servers. Then config-
ure the other hosts to synchronize to the TH directly or indirectly. A
certificate trail is created when Autokey asks the immediately ascen-
dant host towards the TH to sign its certificate, which is then pro-
vided 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 signa-
ture message digest type is MD5, but any combination of sign key type
and message digest type supported by the OpenSSL library can be speci-
fied 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.
File names begin with the prefix ntpkey_ and end with the suffix _host-
name. filestamp, where hostname is the owner name, usually the string
returned by the Unix hostname(1) command, and filestamp is the NTP sec-
onds when the file was generated, in decimal digits. This both guaran-
tees 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 fur-
ther reduce the risk of misconfiguration, the first two lines of a file
contain the file name and generation date and time as comments.
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 crypto-
type 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 cer-
tificates. When complete, start the NTP daemons beginning at the low-
est stratum and working up the tree. It may take some time for Autokey
to instantiate the certificate trails throughout the subnet, but set-
ting up the environment is completely automatic.
If it is necessary to use a different sign key or different digest/sig-
nature scheme than the default, run ntp-keygen with the -S type option,
where type is either RSA or DSA. The most frequent 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. If ntp-keygen is run
again without these options, it generates a new certificate using the
same scheme and sign key, and soft link.
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, and soft links. However, if the host or sign key
is changed, ntpd(1) should be restarted. When ntpd(1) 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.
Identity Schemes
As mentioned on the Autonomous Authentication page, the default TC
identity scheme is vulnerable to a middleman attack. However, there
are more secure identity schemes available, including PC, IFF, GQ and
MV schemes described below. 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 cer-
tificate 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 non-
trusted 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_ RSA key_alice. filestamp and trusted private certificate file
ntpkey_ RSA-MD5 _ cert_alice. filestamp, and soft links. Copy both
files to all group hosts; they replace the files which would be gener-
ated 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 ntp-
key_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 certifi-
cates without copying them to all other hosts in the group, and recre-
ating the soft links.
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_IFF-
par_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 email
program. Copy or email 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 cer-
tificates 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 ntp-
key_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 ntp-
keys_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 dis-
tribution to her clients. It does not 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 clients. 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.
Command Line Options
-b --imbits= modulus
Set the number of bits in the identity modulus for generating
identity keys to modulus bits. The number of bits in the iden-
tity modulus defaults to 256, but can be set to values from 256
to 2048 (32 to 256 octets). Use the larger moduli with caution,
as this can consume considerable computing resources and
increases the size of authenticated packets.
-c --certificate= scheme
Select certificate signature encryption/message digest scheme.
The scheme can be one of the following: RSA-MD2, RSA-MD5, RSA-
MDC2, RSA-SHA, RSA-SHA1, RSA-RIPEMD160, DSA-SHA, or DSA-SHA1.
Note that RSA schemes must be used with an RSA sign key and DSA
schemes must be used with a DSA sign key. The default without
this option is RSA-MD5. If compatibility with FIPS 140-2 is
required, either the DSA-SHA or DSA-SHA1 scheme must be used.
-C --cipher= cipher
Select the OpenSSL cipher to encrypt the files containing pri-
vate keys. The default without this option is three-key triple
DES in CBC mode, des-ede3-cbc. The openssl -h command provided
with OpenSSL displays available ciphers.
-d --debug-level
Increase debugging verbosity level. This option displays the
cryptographic data produced in eye-friendly billboards.
-D --set-debug-level= level
Set the debugging verbosity to level. This option displays the
cryptographic data produced in eye-friendly billboards.
-e --id-key
Write the IFF or GQ public parameters from the IFFkey or GQkey
client keys file previously specified as unencrypted data to the
standard output stream stdout. This is intended for automatic
key distribution by email.
-G --gq-params
Generate a new encrypted GQ parameters and key file for the
Guillou-Quisquater (GQ) identity scheme. This option is mutu-
ally exclusive with the -I and -V options.
-H --host-key
Generate a new encrypted RSA public/private host key file.
-I --iffkey
Generate a new encrypted IFF key file for the Schnorr (IFF)
identity scheme. This option is mutually exclusive with the -G
and Fl V options.
-i --ident= group
Set the optional Autokey group name to group. This is used in
the identity scheme parameter file names of IFF, GQ, and MV
client parameters files. In that role, the default is the host
name if no group is provided. The group name, if specified
using -i or -s following an `@@' character, is also used in cer-
tificate subject and issuer names in the form host @@ group and
should match the group specified via crypto ident or server
ident in the ntpd configuration file.
-l --lifetime= days
Set the lifetime for certificate expiration to days. The
default lifetime is one year (365 days).
-m --modulus= bits
Set the number of bits in the prime modulus for generating files
to bits. The modulus defaults to 512, but can be set from 256
to 2048 (32 to 256 octets). Use the larger moduli with caution,
as this can consume considerable computing resources and
increases the size of authenticated packets.
-M --md5key
Generate a new symmetric keys file containing 10 MD5 keys, and
if OpenSSL is available, 10 SHA keys. An MD5 key is a string of
20 random printable ASCII characters, while a SHA key is a
string of 40 random hex digits. The file can be edited using a
text editor to change the key type or key content. This option
is mutually exclusive with all other options.
-p --password= passwd
Set the password for reading and writing encrypted files to
passwd. These include the host, sign and identify key files.
By default, the password is the string returned by the Unix
hostname command.
-P --pvt-cert
Generate a new private certificate used by the PC identity
scheme. By default, the program generates public certificates.
Note: the PC identity scheme is not recommended for new instal-
lations.
-q --export-passwd= passwd
Set the password for writing encrypted IFF, GQ and MV identity
files redirected to stdout to passwd. In effect, these files
are decrypted with the -p password, then encrypted with the -q
password. By default, the password is the string returned by
the Unix hostname command.
-s --subject-key= [host] [@@ group]
Specify the Autokey host name, where host is the optional host
name and group is the optional group name. The host name, and
if provided, group name are used in host @@ group form as cer-
tificate subject and issuer. Specifying -s -@@ group is
allowed, and results in leaving the host name unchanged, as with
-i group. The group name, or if no group is provided, the host
name are also used in the file names of IFF, GQ, and MV identity
scheme client parameter files. If host is not specified, the
default host name is the string returned by the Unix hostname
command.
-S --sign-key= [RSA | DSA]
Generate a new encrypted public/private sign key file of the
specified type. By default, the sign key is the host key and
has the same type. If compatibility with FIPS 140-2 is
required, the sign key type must be DSA.
-T --trusted-cert
Generate a trusted certificate. By default, the program gener-
ates a non-trusted certificate.
-V --mv-params nkeys
Generate nkeys encrypted server keys and parameters for the Mu-
Varadharajan (MV) identity scheme. This option is mutually
exclusive with the -I and -G options. Note: support for this
option should be considered a work in progress.
Random Seed File
All cryptographically sound key generation schemes must have means to
randomize the entropy seed used to initialize the internal pseudo-ran-
dom number generator used by the library routines. The OpenSSL library
uses a designated random seed file for this purpose. The file must be
available when starting the NTP daemon and ntp-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 pre-
dictable. Various means dependent on external events, such as key-
stroke 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 dae-
mon 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. Since both the ntp-keygen program and
ntpd(1) daemon must run as root, the logical place to put this file is
in /.rnd or /root/.rnd. If the file is not available or cannot be
written, the daemon exits with a message to the system log and the pro-
gram exits with a suitable error message.
Cryptographic Data Files
All file formats begin with two nonencrypted lines. The first line
contains the file name, including the generated host name and
filestamp, in the format ntpkey_key _ name. filestamp, where key is the
key or parameter type, name is the host or group name and filestamp is
the filestamp (NTP seconds) when the file was created. By convention,
key names in generated file names include both upper and lower case
characters, while key names in generated link names include only lower
case characters. The filestamp is not used in generated link names.
The second line contains the datestamp in conventional Unix date for-
mat. Lines beginning with `#' are considered comments and ignored by
the ntp-keygen program and ntpd(1) daemon.
The remainder of the file contains cryptographic data, encoded first
using ASN.1 rules, then encrypted if necessary, and finally written in
PEM-encoded printable ASCII text, preceded and followed by MIME content
identifier lines.
The format of the symmetric keys file, ordinarily named ntp.keys, is
somewhat different than the other files in the interest of backward
compatibility. Ordinarily, the file is generated by this program, but
it can be constructed and edited using an ordinary text editor.
# ntpkey_MD5key_bk.ntp.org.3595864945
# Thu Dec 12 19:22:25 2013
1 MD5 L";Nw<`.I<f4U0)247"i # MD5 key
2 MD5 &>l0%XXK9O'51VwV<xq~ # MD5 key
3 MD5 lb4zLW~d^!K:]RsD'qb6 # MD5 key
4 MD5 Yue:tL[+vR)M`n~bY,'? # MD5 key
5 MD5 B;fx'Kgr/&4ZTbL6=RxA # MD5 key
6 MD5 4eYwa`o}3i@@@@V@@..R9!l # MD5 key
7 MD5 `A.([h+;wTQ|xfi%Sn_! # MD5 key
8 MD5 45:V,r4]l6y^JH6"Sh?F # MD5 key
9 MD5 3-5vcn*6l29DS?Xdsg)* # MD5 key
10 MD5 2late4Me # MD5 key
11 SHA1 a27872d3030a9025b8446c751b4551a7629af65c # SHA1 key
12 SHA1 21bc3b4865dbb9e920902abdccb3e04ff97a5e74 # SHA1 key
13 SHA1 2b7736fe24fef5ba85ae11594132ab5d6f6daba9 # SHA1 key
14 SHA a5332809c8878dd3a5b918819108a111509aeceb # SHA key
15 MD2 2fe16c88c760ff2f16d4267e36c1aa6c926e6964 # MD2 key
16 MD4 b2691811dc19cfc0e2f9bcacd74213f29812183d # MD4 key
17 MD5 e4d6735b8bdad58ec5ffcb087300a17f7fef1f7c # MD5 key
18 MDC2 a8d5e2315c025bf3a79174c87fbd10477de2eabc # MDC2 key
19 RIPEMD160 77ca332cafb30e3cafb174dcd5b80ded7ba9b3d2 # RIPEMD160 key
20 AES128CMAC f92ff73eee86c1e7dc638d6489a04e4e555af878 # AES128CMAC key
Figure 1. Typical Symmetric Key File
Figure 1 shows a typical symmetric keys file used by the reference
implementation. Following the header the keys are entered one per line
in the format
keyno type key
where keyno is a positive integer in the range 1-65535; type is the key
type for the message digest algorithm, which in the absence of the
OpenSSL library must be MD5 to designate the MD5 message digest algo-
rithm; if the OpenSSL library is installed, the key type can be any
message digest algorithm supported by that library; however, if compat-
ibility with FIPS 140-2 is required, the key type must be either SHA or
SHA1; key is the key itself, which is a printable ASCII string 20 char-
acters or less in length: each character is chosen from the 93 print-
able characters in the range 0x21 through 0x7e ( `'! through `~' )
excluding space and the `#' character, and terminated by whitespace or
a `#' character. An OpenSSL key consists of a hex-encoded ASCII string
of 40 characters, which is truncated as necessary.
Note that the keys used by the ntpq(1) and ntpdc(1) 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 symmetric keys file ntp-
key_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. Sub-
sequently, 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(1) and ntpdc(1) utilities.
OPTIONS
-b imbits, --imbits=imbits
identity modulus bits. This option takes an integer number as
its argument. The value of imbits is constrained to being:
in the range 256 through 2048
The number of bits in the identity modulus. The default is 256.
-c scheme, --certificate=scheme
certificate scheme.
scheme is one of RSA-MD2, RSA-MD5, RSA-MDC2, RSA-SHA, RSA-SHA1,
RSA-RIPEMD160, DSA-SHA, or DSA-SHA1.
Select the certificate signature encryption/message digest
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=cipher
privatekey cipher.
Select the cipher which is used to encrypt the files containing
private keys. The default is three-key triple DES in CBC mode,
equivalent to "-C des-ede3-cbc". The openssl tool lists ciphers
available in "openssl -h" output.
-d, --debug-level
Increase debug verbosity level. This option may appear an
unlimited number of times.
-D number, --set-debug-level=number
Set the debug verbosity level. This option may appear an unlim-
ited number of times. This option takes an integer number as
its argument.
-e, --id-key
Write IFF or GQ identity keys.
Write the public parameters from the IFF or GQ client keys to
the standard output. This is intended for automatic key distri-
bution by email.
-G, --gq-params
Generate GQ parameters and keys.
Generate parameters and keys for the GQ identification scheme,
obsoleting any that may exist.
-H, --host-key
generate RSA host key.
Generate new host keys, obsoleting any that may exist.
-I, --iffkey
generate IFF parameters.
Generate parameters for the IFF identification scheme, obsolet-
ing any that may exist.
-i group, --ident=group
set Autokey group name.
Set 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 subject and issuer
names in the form host@@group and should match the ntpd configu-
ration file.
-l lifetime, --lifetime=lifetime
set certificate lifetime. This option takes an integer number
as its argument.
Set the certificate expiration to lifetime days from now.
-m modulus, --modulus=modulus
prime modulus. This option takes an integer number as its argu-
ment. The value of modulus is constrained to being:
in the range 256 through 2048
The number of bits in the prime modulus. The default is 512.
-M, --md5key
generate symmetric keys.
Generate symmetric keys, obsoleting any that may exist.
-P, --pvt-cert
generate PC private certificate.
Generate a private certificate. By default, the program gener-
ates public certificates.
-p passwd, --password=passwd
local private password.
Local files containing private data are encrypted with the DES-
CBC algorithm and the specified password. The same password
must be specified to the local ntpd via the "crypto pw password"
configuration command. The default password is the local host-
name.
-q passwd, --export-passwd=passwd
export IFF or GQ group keys with password.
Export IFF or GQ identity group keys to the standard output,
encrypted with the DES-CBC algorithm and the specified password.
The same password must be specified to the remote ntpd via the
"crypto pw password" configuration command. See also the option
--id-key (-e) for unencrypted exports.
-s host@group, --subject-name=host@group
set host and optionally group name.
Set 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 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.
-S sign, --sign-key=sign
generate sign key (RSA or DSA).
Generate 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.
-T, --trusted-cert
trusted certificate (TC scheme).
Generate a trusted certificate. By default, the program gener-
ates a non-trusted certificate.
-V num, --mv-params=num
generate <num> MV parameters. This option takes an integer num-
ber as its argument.
Generate parameters and keys for the Mu-Varadharajan (MV) iden-
tification scheme.
-v num, --mv-keys=num
update <num> MV keys. This option takes an integer number as
its argument.
This option has not been fully documented.
-?, --help
Display usage information and exit.
-!, --more-help
Pass the extended usage information through a pager.
-> [cfgfile], --save-opts [=cfgfile]
Save the option state to cfgfile. The default is the last con-
figuration file listed in the OPTION PRESETS section, below.
The command will exit after updating the config file.
-< cfgfile, --load-opts=cfgfile, --no-load-opts
Load options from cfgfile. The no-load-opts form will disable
the loading of earlier config/rc/ini files. --no-load-opts is
handled early, out of order.
--version [{v|c|n}]
Output version of program and exit. The default mode is `v', a
simple version. The `c' mode will print copyright information
and `n' will print the full copyright notice.
OPTION PRESETS
Any option that is not marked as not presettable may be preset by load-
ing values from configuration ("RC" or ".INI") file(s) and values from
environment variables named:
NTP_KEYGEN_<option-name> or NTP_KEYGEN
The 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.
USAGE
ENVIRONMENT
See OPTION PRESETS for configuration environment variables.
FILES
See OPTION PRESETS for configuration files.
EXIT STATUS
One of the following exit values will be returned:
0 (EXIT_SUCCESS)
Successful program execution.
1 (EXIT_FAILURE)
The operation failed or the command syntax was not valid.
66 (EX_NOINPUT)
A specified configuration file could not be loaded.
70 (EX_SOFTWARE)
libopts had an internal operational error. Please report it to
autogen-users@lists.sourceforge.net. Thank you.
AUTHORS
The University of Delaware and Network Time Foundation
COPYRIGHT
Copyright (C) 1992-2020 The University of Delaware and Network Time
Foundation all rights reserved. This program is released under the
terms of the NTP license, <http://ntp.org/license>.
BUGS
It can take quite a while to generate some cryptographic values.
Please report bugs to http://bugs.ntp.org .
Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org
NOTES
Portions of this document came from FreeBSD.
This manual page was AutoGen-erated from the ntp-keygen option defini-
tions.
ntp (4.2.8p15) 23 Jun 2020 ntp-keygen(1)
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