Re: [Dnsmasq-discuss] [dnsmasq] DHCP broadcast option

[Simon Kelley]

Ignore my last.

You are confusing the broadcast option, which is an IP address that the 
client can use to send broadcasts to, with the broadcast flag, which 
controls if _DHCP_ packets are broadcast to the client or not.


The reason, that's not being done is that you've configured

dhcp-broadcast=tag:needs-broadcast

which says to force broadcast-to-client mode when the needs-broadcast 
tag is set, but you don't set needs-broadcast anywhere: looking at the logs:


tags: br-nat2

no needs-broadcast tag there.

You need to either set the needs-broadcast flag for the clients which 
need it, or force broadcast unconditionally with a simple


dhcp-broadcast

option.


Cheers,

Simon.



On 14/04/2022 12:20, Gokularajan G T wrote:

Dear Simon,

Looking forward to your thoughts on our observations posted above.

Best Regards,
Gokularajan G T
flag
On Fri, Apr 8, 2022 at 12:47 PM Gokularajan G T > wrote:


Hi Simon,

Thanks for your response. I have collected packet captures, log
dumps and config file. Attaching them.

 From logs we are able to see the broadcast option 28 is requested
and sent in the offer packet.
Apr  8 08:23:16 dnsmasq-dhcp[29720]: 2975419768 requested options:
15:domain-name, 26:mtu, 28:broadcast, 121:classless-static-route,
Apr  8 08:23:16 dnsmasq-dhcp[29720]: 2975419768 sent size:  4
option: 28 broadcast  172.31.7.255

But we are able to see the OFFER packet (packet no: 562) is being
sent as unicast even though the broadcast tag is enabled in the
config file. Please see BOOTP flags.

Please let me know your thoughts.

Best Regards,
Gokularajan G T

On Thu, Apr 7, 2022 at 2:10 PM Simon Kelley mailto:si...@thekelleys.org.uk>> wrote:

There's no regression that I'm aware of. It's worth setting the
log-dhcp
option to see what's going on with tags. Also look at packet
dumps. Is
the "broadcast" flag set in the OFFER packets?

Simon.

On 07/04/2022 08:35, Gokularajan G T wrote:
 > Dear Simon,
 >
 > I believe dnsmasq currently supports the DHCP broadcast
option for OFFER
 > packets with either --dhcp-broadcast command line option or
using
 > "dhcp-broadcast=tag:needs-broadcast" in the config file.
 > Even though we use any of those options, the offer packet
is*always sent
 > as unicast* to the client.
 >
 > Can this be a regression or am I missing something? Need some
 > clarification on this please.
 >
 > I am currently using,
 > dnsmasq version: 2.86
 > OS: Linux
 >
 > Best Regards,
 > Gokularajan



-- 
Gokularajan.G.T

Contact: +919489186237



--
Gokularajan.G.T
Contact: +919489186237


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Re: [Dnsmasq-discuss] [dnsmasq] DHCP broadcast option

[Simon Kelley]

There's no regression that I'm aware of. It's worth setting the log-dhcp 
option to see what's going on with tags. Also look at packet dumps. Is 
the "broadcast" flag set in the OFFER packets?


Simon.

On 07/04/2022 08:35, Gokularajan G T wrote:

Dear Simon,

I believe dnsmasq currently supports the DHCP broadcast option for OFFER 
packets with either --dhcp-broadcast command line option or using 
"dhcp-broadcast=tag:needs-broadcast" in the config file.
Even though we use any of those options, the offer packet is*always sent 
as unicast* to the client.


Can this be a regression or am I missing something? Need some 
clarification on this please.


I am currently using,
dnsmasq version: 2.86
OS: Linux

Best Regards,
Gokularajan


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