TLSDATE(1) User Manuals TLSDATE(1)NAMEtlsdate - secure parasitic rdate replacement
SYNOPSIStlsdate [-hnvVstlw] [-H [hostname]] [-p [port]] [-P
[sslv23|sslv3|tlsv1]] [--certdir [dirname]] [-x [--proxy]
proxy-type://proxyhost:proxyport]
DESCRIPTIONtlsdate is a tool for setting the system clock by hand or by communica‐
tion with the network. It does not set the Real Time Clock. It is
designed to be as secure as TLS (RFC 2246) but of course the security
of TLS is often reduced to whichever CA racket you believe is trustwor‐
thy. By default, tlsdate trusts your local CA root store - so any of
these companies could assist in a MITM attack against you and you'd be
screwed.
This tool is designed to be run by hand or as a system daemon. It must
be run as root or otherwise have the proper caps; it will not be able
to set the system time without running as root or another privileged
user.
OPTIONS-h | --help
Print the help message
-s | --skip-verification
Skip certificate verification
-H | --host [hostname|ip]
Set remote hostname (default: 'google.com')
-n | --dont-set-clock
Do not set the system clock to the time of the remote server
-p | --port [port]
Set remote port (default: '443')
-P | --protocol [sslv23|sslv3|tlsv1]
Set protocol to use when communicating with server (default:
'tlsv1')
-C | --certdir [dirname]
Set the local directory where certificates are located (default:
'/etc/ssl/certs') This allows for certificate or certificate
authority (CA) pinning. To ensure that signatures are only valid
if they are signed by a specific CA or certificate, set the path
to a directory containing only the desired certificates.
-x | --proxy [proxy-type://proxyhost:proxyport]
The proxy argument expects HTTP, SOCKS4A or SOCKS5 formatted as
followed:
http://127.0.0.1:8118
socks4a://127.0.0.1:9050
socks5://127.0.0.1:9050
The proxy support should not leak DNS requests and is suitable
for use with Tor.
-v | --verbose
Provide verbose output
-V | --showtime [human|raw]
Show the time retrieved from the remote server in a human-read‐
able format or as a raw time_t.
-t | --timewarp
If the local clock is before RECENT_COMPILE_DATE; we set the
clock to the RECENT_COMPILE_DATE. If the local clock is after
RECENT_COMPILE_DATE, we leave the clock alone. Clock setting is
performed as the first operation and will impact certificate
verification. Specifically, this option is helpful if on first
boot, the local system clock is set back to the era of Disco and
Terrible Hair. This should ensure that
X509_V_ERR_CERT_NOT_YET_VALID or X509_V_ERR_CERT_HAS_EXPIRED are
not encountered because of a broken RTC or the lack of a local
RTC; we assume that tlsdate is recompiled yearly and that all
certificates are otherwise considered valid.
-l | --leap
Normally, the passing of time or time yet to come ensures that
SSL verify functions will fail to validate certificates. Com‐
monly, X509_V_ERR_CERT_NOT_YET_VALID and
X509_V_ERR_CERT_HAS_EXPIRED are painfully annoying but still
very important error states. When the only issue with the cer‐
tificates in question is the timing information, this option
allows you to trust the remote system's time, as long as it is
after RECENT_COMPILE_DATE and before MAX_REASONABLE_TIME. The
connection will only be trusted if X509_V_ERR_CERT_NOT_YET_VALID
and/or X509_V_OKX509_V_ERR_CERT_HAS_EXPIRED are the only errors
encountered. The SSL verify function will not return X509_V_OK
if there are any other issues, such as self-signed certificates
or if the user pins to a CA that is not used by the remote
server. This is useful if your RTC is broken on boot and you are
unable to use DNSEC until you've at least had some kind of leap
of cryptographically assured data.
-w | --http
Run in web mode: look for the time in an HTTP "Date" header
inside an HTTPS connection, rather than in the TLS connection
itself. The provided hostname and port must support HTTPS.
BUGS
It's likely! Let us know by contacting jacob@appelbaum.net
Note that tlsdate(1) is in Beta, and may not work as expected.
AUTHOR
Jacob Appelbaum <jacob at appelbaum dot net>
SEE ALSOtlsdate(1), tlsdate-helper(1), tlsdated(8), tlsdated.conf(5)Linux OCTOBER 2012 TLSDATE(1)
