NetworkManager DHCP disable DHCP Request "Broadcast" flag

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1

Hello,

Some client of ours is saying that his DHCP server/system is throwing alarms about DHCP “snooping”, and the offending device is a DELL 5001, running Ubuntu Core 16, with our own snaps. It is trying to get a DHCP lease/ip address, but cannot get any. After some wireshark snooping, it turns out that the DHCP requests being sent has this bootp “broadcast” flag enabled, that is most likely causing the issue.

NetworkManager is using it’s own “internal” DHCP client. is there a way we can disable this “broadcast” flag? I have never done it before. As reported by this, the guys patched the system to give the capability to disable it in systemd-system on the network config?

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=797894

[DHCP] RequestBroadcast=false

Any advice?

2

try something like:

nmcli con mod <name of your connection> +ipv4.method auto

that should be the equivalent of “BOOTPROTO=dhcp” which should disable bootp …

3

Hello, We are looking to change the bootp flag from “broadcast” to “unicast”. (Your method +ipv4.method auto in this case did not work.)

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Thanks.

4

perhaps @abeato has another idea …