Yeah, I'm puzzled as well, I patched the init script to show entry and no-carrier exit of dhcp_check() and, on an AR300M-Lite (with cable plugged in its single jack) I see it checking br-lan which is downhas no carrier at first, then comes up.
$ diff -u dnsmasq.orig dnsmasq
--- dnsmasq.orig 2019-03-01 09:17:35.000000000 -0800
+++ dnsmasq 2019-03-01 09:17:35.000000000 -0800
@@ -65,12 +65,16 @@
local stamp="${BASEDHCPSTAMPFILE_CFG}.${ifname}.dhcp"
local rv=0
+ logger -t dnsmasq "Entry dhcp_check() $@"
+
[ -s "$stamp" ] && return $(cat "$stamp")
# If there's no carrier yet, skip this interface.
# The init script will be called again once the link is up
case "$(devstatus "$ifname" | jsonfilter -e @.carrier)" in
- false) return 1;;
+ false)
+ logger -t dnsmasq "Exit dhcp_check() -- $ifname has no carrier"
+ return 1;;
esac
udhcpc -n -q -s /bin/true -t 1 -i "$ifname" >&- && rv=1 || rv=0
root@OpenWrt:~# logread | fgrep dnsmasq
Fri Mar 1 16:50:10 2019 user.notice dnsmasq: DNS rebinding protection is active, will discard upstream RFC1918 responses!
Fri Mar 1 16:50:10 2019 user.notice dnsmasq: Allowing 127.0.0.0/8 responses
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: started, version 2.80 cachesize 150
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: DNS service limited to local subnets
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP no-DHCPv6 no-Lua TFTP no-conntrack no-ipset no-auth no-DNSSEC no-ID loop-detect inotify dumpfile
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: using local addresses only for domain test
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: using local addresses only for domain onion
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: using local addresses only for domain localhost
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: using local addresses only for domain local
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: using local addresses only for domain invalid
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: using local addresses only for domain bind
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: using local addresses only for domain lan
Fri Mar 1 16:50:11 2019 daemon.warn dnsmasq[773]: no servers found in /tmp/resolv.conf.auto, will retry
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: read /etc/hosts - 4 addresses
Fri Mar 1 16:50:11 2019 daemon.info dnsmasq[773]: read /tmp/hosts/dhcp.cfg01411c - 0 addresses
Fri Mar 1 16:50:18 2019 user.notice dnsmasq: Entry dhcp_check() br-lan
Fri Mar 1 16:50:18 2019 user.notice dnsmasq: Exit dhcp_check() -- br-lan has no carrier
Fri Mar 1 16:50:18 2019 daemon.info dnsmasq[773]: read /etc/hosts - 4 addresses
Fri Mar 1 16:50:18 2019 daemon.info dnsmasq[773]: read /tmp/hosts/dhcp.cfg01411c - 0 addresses
Fri Mar 1 16:50:19 2019 user.notice dnsmasq: Entry dhcp_check() br-lan
Fri Mar 1 16:50:22 2019 daemon.info dnsmasq[773]: exiting on receipt of SIGTERM
Fri Mar 1 16:50:22 2019 daemon.info dnsmasq[1229]: started, version 2.80 cachesize 150
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: DNS service limited to local subnets
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP no-DHCPv6 no-Lua TFTP no-conntrack no-ipset no-auth no-DNSSEC no-ID loop-detect inotify dumpfile
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq-dhcp[1229]: DHCP, IP range 192.168.1.100 -- 192.168.1.249, lease time 12h
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: using local addresses only for domain test
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: using local addresses only for domain onion
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: using local addresses only for domain localhost
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: using local addresses only for domain local
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: using local addresses only for domain invalid
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: using local addresses only for domain bind
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: using local addresses only for domain lan
Fri Mar 1 16:50:23 2019 daemon.warn dnsmasq[1229]: no servers found in /tmp/resolv.conf.auto, will retry
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: read /etc/hosts - 4 addresses
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: read /tmp/hosts/dhcp.cfg01411c - 2 addresses
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq-dhcp[1229]: read /etc/ethers - 0 addresses
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: read /etc/hosts - 4 addresses
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq[1229]: read /tmp/hosts/dhcp.cfg01411c - 2 addresses
Fri Mar 1 16:50:23 2019 daemon.info dnsmasq-dhcp[1229]: read /etc/ethers - 0 addresses
Fri Mar 1 17:26:35 2019 user.info kernel: [ 10.301747] kmodloader: done loading kernel modules from /etc/modules.d/*
Fri Mar 1 17:26:35 2019 user.notice dnsmasq: DNS rebinding protection is active, will discard upstream RFC1918 responses!
Fri Mar 1 17:26:35 2019 user.notice dnsmasq: Allowing 127.0.0.0/8 responses
Fri Mar 1 17:26:36 2019 daemon.info dnsmasq[773]: started, version 2.80 cachesize 150
Fri Mar 1 17:26:39 2019 user.notice rc.local: Running rc.local
Fri Mar 1 17:26:41 2019 daemon.notice netifd: Interface 'lan' is enabled
Fri Mar 1 17:26:41 2019 daemon.notice netifd: Interface 'lan' is setting up now
Fri Mar 1 17:26:41 2019 kern.info kernel: [ 18.144462] IPv6: ADDRCONF(NETDEV_UP): br-lan: link is not ready
Fri Mar 1 17:26:41 2019 daemon.notice netifd: Interface 'lan' is now up
Fri Mar 1 17:26:41 2019 user.notice firewall: Reloading firewall due to ifup of lan (br-lan)
Fri Mar 1 17:26:43 2019 daemon.notice netifd: Network device 'eth0' link is up
Fri Mar 1 17:26:43 2019 daemon.notice netifd: bridge 'br-lan' link is up
Fri Mar 1 17:26:43 2019 daemon.notice netifd: Interface 'lan' has link connectivity
Fri Mar 1 17:26:43 2019 kern.info kernel: [ 20.269103] IPv6: ADDRCONF(NETDEV_CHANGE): br-lan: link becomes ready
Fri Mar 1 17:26:44 2019 user.notice dnsmasq: Entry dhcp_check() br-lan
Fri Mar 1 17:26:44 2019 kern.info kernel: [ 21.255202] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
Fri Mar 1 17:26:44 2019 daemon.notice netifd: Network device 'wlan0' link is up
Fri Mar 1 17:26:47 2019 daemon.info dnsmasq[773]: exiting on receipt of SIGTERM
Fri Mar 1 17:26:48 2019 daemon.info dnsmasq[1247]: started, version 2.80 cachesize 150
to /etc/rc.local so that dnsmasq is definitely restarted when everything is finished. I did not plug a LAN cable until I was sure that everything was done. This also does not help. Dnsmasq restarts, but no IPv4 address via DHCP.
Have you tried option force_link 1 in the LAN configuration?
This makes no sense though because the MT7620 has an internal switch between eth0 and the physical ports. eth0 always has carrier from the switch whether or not cable(s) are plugged in.
No, the fresh and untouched installation without any configuration file touched yet behaves like this: No DHCPv4 via LAN (and also not via WLAN if one enables it) if no LAN cable is plugged to the "LAN" port during boot.
That's why I filed a bug about this: This is imo a severe issue because the router lacks fundamental functionality after flashing OpenWrt!
@Pippo It has been clearly and repeatedly established in multiple ways what is and is not running and when. It has been shown that the config file differs in a line directly related to DHCP. Perhaps if you have basic questions about the operation of OpenWrt they could be asked on your own thread. They are more than “slightly off topic” as you describe them, especially at this point in the thread.
With some coffee in me this morning, let me explain why. /etc/init.d/network is a shell script. Its behavior can be understood by reading the script, or, in your case of a single point of behavior, checked on your own device. The output of netstat does not show a listener for DHCP, so the wireless association or client behavior is irrelevant. If a DHCP server were running, you'd see a line such as
The problem happens/shows up inside the dhcp_check() function of the init script. I added some debugging messages (similarily to what you did earlier) to find out what exactly happens.
In both cases (plugged/unplugged), this function is called only once, with $ifname set to "br-lan" and $stamp set to "/var/run/dnsmasq.cfg01411c.br-lan.dhcp".
If the LAN cable is plugged, the function completes and returns 0 at the end, which then results in the dhcp-range line being added to the config by dhcp_add().
If no LAN cable is plugged, the function returns at
# If there's no carrier yet, skip this interface.
# The init script will be called again once the link is up
case "$(devstatus "$ifname" | jsonfilter -e @.carrier)" in
false) return 1;;
esac
This causes dhcp_add() to return before the dhcp-range line is added.
When the device boots up without a LAN cable plugged and one sets an IP address manually (or uses the IPv6 DHCP address which can be obtained in this case), logs in and runs
devstatus br-lan | jsonfilter -e @.carrier
it returns "true".
So I'm pretty sure that this is some hardware-specific timing problem or similar. I'm not deep enough into OpenWrt (yet), but it looks like the LAN bridge does not have a "carrier" without a LAN cable being plugged when it should have one.
I updated it, but it doesn't change anything. The behavior is still the same.
@Pippo: I'm not sure if I understand your question … yes, this is the router I'm talking about and apart of the WAN/LAN ports having a gray border instead of a yellow one, it looks exacly like the photos of the linked hardware page.
Hi I have reported the same problem. I do have work around a service the stop and start the dnsmasq two calls. Reload will not work. I think the problem is in
This must start race problem with dhcp_check I think changing the order and adding sleep will solve the problem, as you could run in to real problems I have not tried it yet. I need to trace a little more.
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