NTP traffic in loopback

Started by Syon, January 05, 2023, 04:48:00 PM

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I have a question, I noticed that on the loopback (lo0) NTP requests rush through every second.
Is this normal behavior? I came across it when I wanted to forward all ntp requests to the OPNSense. This works wonderfully and for the lo0 it makes no difference whether the forward rules are on or off.
Thanks for reading.

January 06, 2023, 08:33:13 AM #1 Last Edit: January 06, 2023, 08:40:27 AM by Syon
So, if I kill the ntp-service, then only the Code 2 read command without the response is left.
What tests the ntp-variables so frequently?
Full info:
read
Frame 7: 44 bytes on wire (352 bits), 44 bytes captured (352 bits) on interface -, id 0
Null/Loopback
Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
User Datagram Protocol, Src Port: 21338, Dst Port: 123
Network Time Protocol (NTP Version 2, control)
    Flags: 0x16, Leap Indicator: no warning, Version number: NTP Version 2, Mode: reserved for NTP control message
    Flags 2: 0x02, Response bit: Request, Opcode: read variables
    Sequence: 1
    [Response In: 8]
    Status: 0x0000
    AssociationID: 0
    Offset: 0
    Count: 0


response
Frame 8: 436 bytes on wire (3488 bits), 436 bytes captured (3488 bits) on interface -, id 0
Null/Loopback
Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
User Datagram Protocol, Src Port: 123, Dst Port: 21338
Network Time Protocol (NTP Version 2, control)
    Flags: 0x16, Leap Indicator: no warning, Version number: NTP Version 2, Mode: reserved for NTP control message
    Flags 2: 0x82, Response bit: Response, Opcode: read variables
    Sequence: 1
    [Request In: 7]
    [Delta Time: 0.000136000 seconds]
    Status: 0x0615, Leap Indicator: no warning, Clock Source: UDP/NTP, System Event Code: clock synchronized
    AssociationID: 0
    Offset: 0
    Count: 392
    Data
        version="ntpd 4.2.8p15@1.3728-o Mon Jul 25 03:38:19 UTC 2022 (1)"
        processor="amd64"
        system="FreeBSD/13.1-RELEASE-p5"
        leap=0
        stratum=4
        precision=-23
        rootdelay=26.611
        rootdisp=89.823
        refid=185.11.138.90
        reftime=0xe7624e9c.f1d5789c
        clock=0xe7624ea1.3f65b643
        peer=54765
        tc=6
        mintc=3
        offset=-3.960432
        frequency=-26.606
        sys_jitter=4.671442
        clk_jitter=1.115
        clk_wander=0.001