From Newsgroup: comp.protocols.time.ntp

Recently IrCOve been toying with a GPS receiver, and it occured to
me that I can configure the NTP instances of two of my boxes
(connected over a Fast Ethernet link) to use each other as rCybackuprCO
time source. Per ntp/assoc.html , it would seem that I need rCypeerrCO
association type for that:

a> Symmetric active/passive mode is intended for configurations where a
a> clique of low-stratum peers operate as mutual backups for each other.
a> Each peer operates with one or more primary reference sources, such
a> as a reference clock, or a set of secondary (stratum, 2) servers known
a> to be reliable and authentic. [rCa]

In this case, one of the boxes has better Internet connectivity,
allowing for the use of the NTP pool servers as its reference
clock; and the other has said GPS receiver connected.

To my surprise, IrCOve found that as part of the rCyhardeningrCO effort
for NTPsec (the version included in Debian Trixie) the rCypeerrCO
association type got removed; this is what I get in syslog:

CONFIG: peer deprecated, treated as server: (peer-IP-address)

The question is: what is the best current practice for having
rCya clique of low-stratum peers operate as mutual backups for each
otherrCO? Is rCypeerrCO truly deprecated for any and all possible uses?
Are there any rCyhardenedrCO NTP implementations that /do/ support
rCypeerrCO? Or is it that those interested in such configurations
are ought to rely on the Reference Implementation?

(JFTR, I donrCOt see any mention of a function like that in OpenNTPdrCOs
ntpd.conf(5), either. Conversely, the machine to which the GPS
receiver is connected runs NTP 4.2.8p15 from NetBSD 10.1 and, so
far as I can tell, has no trouble with rCypeerrCO.)

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From Newsgroup: comp.protocols.time.ntp

On 3/19/2026 6:25 AM, Ivan Shmakov wrote:

Recently IrCOve been toying with a GPS receiver, and it occured to
me that I can configure the NTP instances of two of my boxes
(connected over a Fast Ethernet link) to use each other as rCybackuprCO
time source. Per ntp/assoc.html , it would seem that I need rCypeerrCO
association type for that:

a> Symmetric active/passive mode is intended for configurations where a
a> clique of low-stratum peers operate as mutual backups for each other.
a> Each peer operates with one or more primary reference sources, such
a> as a reference clock, or a set of secondary (stratum, 2) servers known
a> to be reliable and authentic. [rCa]

In this case, one of the boxes has better Internet connectivity,
allowing for the use of the NTP pool servers as its reference
clock; and the other has said GPS receiver connected.

To my surprise, IrCOve found that as part of the rCyhardeningrCO effort
for NTPsec (the version included in Debian Trixie) the rCypeerrCO
association type got removed; this is what I get in syslog:

CONFIG: peer deprecated, treated as server: (peer-IP-address)

The question is: what is the best current practice for having
rCya clique of low-stratum peers operate as mutual backups for each
otherrCO? Is rCypeerrCO truly deprecated for any and all possible uses?
Are there any rCyhardenedrCO NTP implementations that /do/ support
rCypeerrCO? Or is it that those interested in such configurations
are ought to rely on the Reference Implementation?

(JFTR, I donrCOt see any mention of a function like that in OpenNTPdrCOs
ntpd.conf(5), either. Conversely, the machine to which the GPS
receiver is connected runs NTP 4.2.8p15 from NetBSD 10.1 and, so
far as I can tell, has no trouble with rCypeerrCO.)

If you're running "real" NTP - from the NTP Project, why would you not
want to run the latest -stable code on production boxes?

See https://downloads.nwtime.org/ntp/ChangeLog-stable for what's been
changed since p15, for example.
--
Harlan Stenn <stenn@ntp.org>
NTP Project Lead. The NTP Project is part of
https://www.nwtime.org/ - be a member!I



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From Newsgroup: comp.protocols.time.ntp

On Thu, Mar 19, 2026 at 01:25:23PM +0000, Ivan Shmakov wrote:

To my surprise, IrCOve found that as part of the rCyhardeningrCO effort
for NTPsec (the version included in Debian Trixie) the rCypeerrCO
association type got removed; this is what I get in syslog:

CONFIG: peer deprecated, treated as server: (peer-IP-address)

The question is: what is the best current practice for having
rCya clique of low-stratum peers operate as mutual backups for each
otherrCO? Is rCypeerrCO truly deprecated for any and all possible uses?

"peer" configures a symmetric association. "server" configures a
client-server association. A symmetric association can be fully
replaced by two client-server associations in the opposite directions.
It just doubles the network traffic. Basically, the client-server mode
is a special case of the symmetric mode. NTP originally had only
the symmetric mode, later was added client-server mode, and couple
decades later the symmetric mode might be removed from NTP completely.

The current best practice for "a clique of low-stratum peers operate
as mutual backups for each other" is the same except use "server"
instead of "peer".

The only interesting feature of the symmetric mode is that time can be
pushed to a host that doesn't specify the other peer in its config.
The disadvantages are much more difficult implementation, worse
security, and less accurate measurement of the network delay due to
much larger intervals between requests and responses.
--
Miroslav Lichvar

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