Subject: [ntpwg] [Technical Errata Reported] RFC5905 (3613)

From: RFC Errata System <[email-masked]>
Date: Mon, 6 May 2013 01:33:04 -0700 (PDT)

The following errata report has been submitted for RFC5905,
"Network Time Protocol Version 4: Protocol and Algorithms Specification".

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You may review the report below and at:
http://www.rfc-editor.org/errata_search.php?rfc=5905&eid=3613

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Type: Technical
Reported by: Tony O'Brien <[email-masked]>

Section: 8

Original Text
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Corrected Text
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Notes
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In the paragraph explaining the sanity checks on received packets, it states: "In the exchange above, a packet is duplicate or replay if the transmit timestamp t3 in the packet matches the org state variable T3."  But in the pseudo-code in A.5.1 it states

        /*

         * If the transmit timestamp duplicates a previous one, the

         * packet is a replay.

         */

        if (r->xmt == p->xmt)

i.e. comparing the transmit timestamp p->xmt with the xmt state variable T1.  Which is correct?

Similarly for the check for a bogus packet, Section 8 states: "A packet is bogus if the origin timestamp t1 in the packet does not match the xmt state variable T1.  But the pseudo-code says:

        /*

         * If this is a broadcast mode packet, skip further checking.

         * If the origin timestamp is zero, the sender has not yet heard

         * from us.  Otherwise, if the origin timestamp does not match

         * the transmit timestamp, the packet is bogus.

         */

        synch = TRUE;

        if (r->mode != M_BCST) {

                if (r->org == 0)

                        synch = FALSE;  /* unsynchronized */

                else if (r->org != p->xmt)

                        synch = FALSE;  /* bogus packet */

        }

i.e. it is comparing the transmit timestamp t3 in the packet with the org state variable T3.

Which is correct?  Looking at Figure 15 my guess would be Section 8 is correct but I have seen code that more closely follows the pseudo-code.

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RFC5905 (draft-ietf-ntp-ntpv4-proto-13)
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Title               : Network Time Protocol Version 4: Protocol and Algorithms Specification
Publication Date    : June 2010
Author(s)           : D. Mills, J. Martin, Ed., J. Burbank, W. Kasch
Category            : PROPOSED STANDARD
Source              : Network Time Protocol
Area                : Internet
Stream              : IETF
Verifying Party     : IESG
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