[Dnsmasq-discuss] dnsmasq dhcp relay not relaying response from upstream to client

Geert Stappers stappers at stappers.nl
Sat Jun 26 16:57:20 UTC 2021


On Sat, Jun 26, 2021 at 11:52:10AM +0700, Bino Oetomo wrote:
> On Sat, Jun 26, 2021 at 4:12 AM Geert Stappers <stappers at stappers.nl> wrote:
> > On Fri, Jun 25, 2021 at 11:30:18AM +0700, Bino Oetomo wrote:
> > > but how to know if dnsmasq is receiving that response?
> >
> >   ... use networksniffer at **server** to verify that
> >        the network packets actual do leave 'freeradius'
> >        at the correct network interface.
> >
> > Next step will be netsniffing at the DHCP relay computer.
> >
> I'm not good in network sniffing.

Luckly there is now a good reason to get more comfortable with it.


> This is tcpdump  at the relay :
> 
> 11:42:41.275012 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 08:00:27:84:51:1b, length 300
> 11:42:41.275324 IP 10.10.253.1.67 > 10.10.254.1.67: BOOTP/DHCP, Request from 08:00:27:84:51:1b, length 300
> 11:42:41.433288 IP 10.10.254.1.67 > 10.10.253.1.67: BOOTP/DHCP, Reply, length 301
> 11:42:45.558901 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 08:00:27:84:51:1b, length 300
> 11:42:45.559148 IP 10.10.253.1.67 > 10.10.254.1.67: BOOTP/DHCP, Request from 08:00:27:84:51:1b, length 300
> 11:42:45.721512 IP 10.10.254.1.67 > 10.10.253.1.67: BOOTP/DHCP, Reply, length 301
> 11:42:56.982058 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 08:00:27:84:51:1b, length 300
> 11:42:56.982472 IP 10.10.253.1.67 > 10.10.254.1.67: BOOTP/DHCP, Request from 08:00:27:84:51:1b, length 300
> 11:42:57.113442 IP 10.10.254.1.67 > 10.10.253.1.67: BOOTP/DHCP, Reply, length 301
> 
> Againt, I'm pretty sure that freeradius sent the response and it reach the
> relay.

Yes, `tcpdump` does proof that.

 
> But, still got the same conndition and client side
> 
> root at bakalandebian:~# dhclient -d enp0s8
       ...
> DHCPDISCOVER on enp0s8 to 255.255.255.255 port 67 interval 3
> DHCPDISCOVER on enp0s8 to 255.255.255.255 port 67 interval 7
> DHCPDISCOVER on enp0s8 to 255.255.255.255 port 67 interval 14
> No DHCPOFFERS received.
> No working leases in persistent database - sleeping.
> 
> Yes isc-dhcp-relay works,
> but I need to stick with dnsmasq since I need to take care about iPXE.
 
I'm also here for the great combination of iPXE and dnsmasq.


> > So kindly please help me to fix this problem
> >
> > That was recieved as
> >
> >   Kindly help me with diagnosing a problem.
> >
> >
> > Already started   :-)
> >

And there is the good observation from Nicolas Cavallari 

I suggest to continue the email thread there.

 

> > > log-dhcp
> > > dhcp-relay=10.10.253.1,10.10.254.1
> >
> > Manual page dnsmasq snippet:
> >    --dhcp-relay=<local address>,<server address>[,<interface]
> >
> > So the 'dhcp-relay=10.10.253.1,10.10.254.1' looks good ...
> >
> I edited it to --> dhcp-relay=10.10.253.1,10.10.254.1,enp0s8
> enp0s8 is facing freeradius.

Acknowledge


> I Apologize for my bad english

Advice:
* Focus on the technical challenge  ( focus on the "original problem" )
* Prevent getting exhausted on non-native language stuff


> Dear Geert Stappers
> I really apprecate your help
 
We all appreciate a healthy community.


 
Groeten
Geert Stappers
-- 
Silence is hard to parse



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