[ISSUE] DHCP Broadcasts blocked - adb connection drops

[Uj947nXmRqV2nRaWshKtHzTvckUUpD]

Android System (1000) is being blocked periodically (i think when dhcp ip renew is about to happen).

Denied 12 times in one hour (from firewall logs):

wlan0
Dest: 255.255.255.255:67
Host: 255.255.255.255
Source: 192.168.0.X:68 (my phone's wlan ip)
Protocol UDP

I am on Android 10 rooted with magisk ( + edpxosed module ) and issue occurs on both 3.4.0 and 3.5.0 beta 1 versions .

My afwall configuration is one 'whitelist mode' and I only allow selected. For System(pid 1000) LAN and VPN is allowed only.

Note that some days ago I was having full connection drops without recovering when fully blocking PID 1000 on LAN. i was seeing blocked connections from my ip:68 towards 192.168.100.1:67 (my gateway = my router's ip). After allowing it on LAN, these are gone, only broadcasts are blocked.

Adb wifi connection drops with errors (from logcat):

10-10 04:53:04.955 1693 2312 V AlarmManager: Triggering alarm #0: 2 when =2965835 package =com.android.networkstack.inprocess operation = null listenTag =DhcpClient.wlan0.KICK flags =0x9
10-10 04:53:04.957 1693 2898 D DhcpClient: Broadcasting DHCPREQUEST ciaddr=192.168.0.X request=0.0.0.0 serverid=null
10-10 04:53:04.959 1693 2898 E DhcpClient: Can't send packet:
10-10 04:53:04.959 1693 2898 E DhcpClient: android.system.ErrnoException: sendto failed: EPERM (Operation not permitted)
10-10 04:53:04.959 1693 2898 E DhcpClient: at libcore.io.Linux.sendtoBytes(Native Method)
10-10 04:53:04.959 1693 2898 E DhcpClient: at libcore.io.Linux.sendto(Linux.java:225)
10-10 04:53:04.959 1693 2898 E DhcpClient: at libcore.io.ForwardingOs.sendto(ForwardingOs.java:193)
10-10 04:53:04.959 1693 2898 E DhcpClient: at libcore.io.BlockGuardOs.sendto(BlockGuardOs.java:358)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.system.Os.sendto(Os.java:522)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.net.dhcp.DhcpClient.transmitPacket(DhcpClient.java:463)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.net.dhcp.DhcpClient.sendRequestPacket(DhcpClient.java:500)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.net.dhcp.DhcpClient.access$2600(DhcpClient.java:116)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.net.dhcp.DhcpClient$DhcpReacquiringState.sendPacket(DhcpClient.java:1053)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.net.dhcp.DhcpClient$PacketRetransmittingState.processMessage(DhcpClient.java:787)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.net.networkstack.util.StateMachine$SmHandler.processMsg(StateMachine.java:992)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.net.networkstack.util.StateMachine$SmHandler.handleMessage(StateMachine.java:809)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.os.Handler.dispatchMessage(Handler.java:107)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.net.networkstack.util.WakeupMessage.onAlarm(WakeupMessage.java:133)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.app.AlarmManager$ListenerWrapper.run(AlarmManager.java:263)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.os.Handler.handleCallback(Handler.java:883)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.os.Handler.dispatchMessage(Handler.java:100)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.os.Looper.loop(Looper.java:214)
10-10 04:53:04.959 1693 2898 E DhcpClient: at android.os.HandlerThread.run(HandlerThread.java:67)
10-10 04:53:04.965 1693 2898 D DhcpClient: doQuit
10-10 04:53:04.968 1693 2898 D ApfFilter: (wlan0): shutting down

Let me know if more info is needed, I am glad to provide it.

[Uj947nXmRqV2nRaWshKtHzTvckUUpD]

I managed to workaround the issue with a custom script set in afwall:
iptables -I afwall-wifi 1 -o wlan0 -s 192.168.0.0/16 -d 255.255.255.255 -p udp --sport 68 --dport 67 -j ACCEPT -m comment --comment "Allow DHCP request broadcast"

#supposing that your lan is somewhere in 192.168.0.0/16

Still, this doesn't answer the question why this occurs? Is it a bug?
@ukanth Can you please shed some light on this . Thank you!

[ukanth]

Have you enabled DHCP from the list ?