LEDE as Stratum 1 NTP server using USB GPS

Installing and Using OpenWrt
22

Hi,
I also got the same result: no /etc/ntp.conf. I'm running OpenWrt 19.07.3 r11063-85e04e9f46 / LuCI openwrt-19.07 branch git-20.247.75781-0d0ab01.

What I noticed is that ntpd generates the ntpd.conf under /var/etc/ every time it starts parsing /etc/config/system for timeserver section for the list of ntp servers. I made some modifications to /etc/init.d/ntpd file to look like following:

#!/bin/sh /etc/rc.common
# Copyright (C) 2006-2011 OpenWrt.org

START=65
STOP=65

USE_PROCD=1
PROG=/sbin/ntpd
HOTPLUG_HELPER=/usr/sbin/ntpd.hotplug-helper

config_file=/var/etc/ntpd.conf

trunc() {
        echo -n "" > $config_file
}

emit() {
        echo -e "$@" >> $config_file
}

validate_ntp_section() {
        uci_load_validate system timeserver "$1" "$2" \
                'server:list(host)' 'enabled:bool:1' 'enable_server:bool:0' \
                'interface:list(string)'
}

start_ntpd_instance() {
        local intf i

        [ "$2" = 0 ] || {
                echo "validation failed"
                return 1
        }

        [ "$enabled" = 0 ] && return

 [ -z "$server" -a "$enable_server" = 0 ] && return

        # not sure that the interfaces enumerated should be validated,
        # since some of them might be dynamic interfaces (like IPsec
        # tunnels) which aren't known by ubus.

        mkdir -p "$(dirname "$config_file")"

        trunc
        emit "driftfile /var/lib/ntp/ntp.drift\n"

        if [ "$enable_server" != 0 ]; then
                emit "restrict default limited kod nomodify notrap nopeer"
                emit "restrict -6 default limited kod nomodify notrap nopeer"
        else
                emit "restrict -4 default noserve"
                emit "restrict -6 default noserve"
        fi
        emit "restrict source noquery"

        emit "\n# No limits for local monitoring"
        emit "restrict 127.0.0.1"
        emit "restrict -6 ::1\n"

        emit "\n# GPS"
        emit "server 127.127.28.0 minpoll 4 prefer"
        emit "fudge 127.127.28.0 refid GPS\n"

if [ -n "$interface" ]; then
                local loopback=$(ubus call network.interface dump | jsonfilter -e "@.interface[@.interface='loopback']['device']")

                local saw_lo=
                for intf in $interface; do
                        emit "interface listen $intf"
                        [ "$intf" = "$loopback" ] && saw_lo=1
                done
                [ -z "$saw_lo" ] && emit "interface listen $loopback"
                emit ""
        fi

        emit "\n# Servers or Pools found in /etc/config/system  timeserver section"

        for i in $server
        do
                emit "server $i iburst"
        done

        mkdir -p /var/lib/ntp
        chown -R ntp:ntp /var/lib/ntp

        procd_open_instance
        procd_set_param command $PROG -g -u ntp:ntp -p /var/run/ntpd.pid -n \
                -c $config_file
        procd_close_instance

        procd_open_instance
        procd_set_param command $HOTPLUG_HELPER
        procd_close_instance
}


start_service() {
        validate_ntp_section ntp start_ntpd_instance
}

service_triggers() {
        procd_add_reload_trigger "system"
        procd_add_validation validate_ntp_section
}

with my changes being:

...
        emit "\n# GPS"
        emit "server 127.127.28.0 minpoll 4 prefer"
        emit "fudge 127.127.28.0 refid GPS\n"
...
        emit "\n# Servers or Pools found in /etc/config/system  timeserver section"

Must make these changes every time ntpd is upgraded, till someone in the project pushes these modifications to the package.

Hope this hleps someone

2 Likes
23

Only reading the title, you'd be a Stratum 0 server if getting time from GPS. Just wanted to be clear.

24

Nope: stratum 0 would be the GPS itself, the computer that controls the GPS becomes stratum 1. A NTP server can never announce itself as stratum 0.

1 Like
25

Well, depends on how they're connected (USB ain't it) - I stand corrected