On Tue, Oct 20, 2020 at 09:25:01PM +0200, Daniele Riccucci wrote:
Hello,
I'm trying to push a different DNS server via DHCP to a specific client (a
VoIP thingie from Grandstream, model HT802) from an EdgeRouter; the current
firmware is running Dnsmasq version 2.79-1-2-geff17ee.
Some options are already generated by the OS unfortunately, namely:
dhcp-range=set:home,10.0.0.20,10.0.0.254,255.255.255.0,86400
domain=home.domain.com,10.0.0.0/24,local
dhcp-option=tag:home,option:domain-name,home.domain.com
dhcp-option=tag:home,option:router,10.0.0.1
dhcp-option=tag:home,option:dns-server,10.0.0.1
dhcp-host=c0:74:ad:0c:0c:b7,set:home,10.0.0.5
host-record=voipgw.home.domain.com,10.0.0.5,86400
which are contained in /etc/dnsmasq.d/dnsmasq-dhcp-config.conf.
I can only set options above this point (/etc/dnsmasq.conf), and I tried
with:
dhcp-option=tag:home,option:dns-server,10.0.0.1
options dhcp-option=vendor:HT8XX,option:dns-server,85.38.28.0,85.38.28.1
options
dhcp-option-force=vendor:HT8XX,option:dns-server,85.38.28.0,85.38.28.1
because from tcpdump I saw that the client was sending a Vendor-Class
string:
c0:74:ad:0c:0c:b7 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 590:
(tos 0x0, ttl 64, id 0, offset 0, flags [none], proto UDP (17), length 576)
0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from
c0:74:ad:0c:0c:b7, length 548, xid 0xbed7bb5e, Flags [none]
Client-Ethernet-Address c0:74:ad:0c:0c:b7
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether c0:74:ad:0c:0c:b7
Hostname Option 12, length 6: "voipgw"
Vendor-Class Option 60, length 18: "HT8XX dslforum.org"
Parameter-Request Option 55, length 17:
Subnet-Mask, Time-Zone, Default-Gateway, Domain-Name-Server
Hostname, Domain-Name, TTL, BR
Static-Route, NTP, Vendor-Option, Lease-Time
Server-ID, TFTP, Classless-Static-Route, Option 125
Option 160
However, the reply from dnsmasq is sending 10.0.0.1 as DNS server:
20:19:01.081957 24:a4:3c:b3:c2:8d > c0:74:ad:0c:0c:b7, ethertype IPv4
(0x0800), length 390: (tos 0xc0, ttl 64, id 53937, offset 0, flags [none],
proto UDP (17), length 376)
10.0.0.1.67 > 10.0.0.5.68: BOOTP/DHCP, Reply, length 348, xid
0xbed7bb5e, Flags [none]
Client-IP 10.0.0.5
Server-IP 10.0.0.1
Client-Ethernet-Address c0:74:ad:0c:0c:b7
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: ACK
Server-ID Option 54, length 4: 10.0.0.1
Lease-Time Option 51, length 4: 86358
Subnet-Mask Option 1, length 4: 255.255.255.0
BR Option 28, length 4: 10.0.0.255
Hostname Option 12, length 6: "voipgw"
Domain-Name-Server Option 6, length 4: 10.0.0.1
Option 6
Default-Gateway Option 3, length 4: 10.0.0.1
Domain-Name Option 15, length 15: "home.domain.com"
Vendor-Option Option 43, length 21:
6.8.85.38.28.0.85.38.28.1.
Option 6, eight bytes, dns.ser.ver.0, dns.ser.ver.1
\ 6.8.85.38.28.0.85.38.28.1.255
Option 6, eight bytes, dns.ser.ver.0, dns.ser.ver.1, end
Vendor-Class Option 60, length 18: "HT8XX dslforum.org"
Also shown from the device:
Product Model: HT802
MAC Address: c0:74:ad:0c:0c:b7
Network:
IPv4 Address -- 10.0.0.5
IPv6 Address --
Netmask -- 255.255.255.0
Gateway -- 10.0.0.1
DNS Server -- 10.0.0.1
How could I solve this? Is there a way to override the dns-server option for
this device?
Something like changing the
| dhcp-host=c0:74:ad:0c:0c:b7,set:home,10.0.0.5
| host-record=voipgw.home.domain.com,10.0.0.5,86400
in
| dhcp-host=c0:74:ad:0c:0c:b7,set:myvoiptag,10.0.0.5,voipgw
| dhcp-option=tag:myvoiptag,option:dns-server,85.38.28.1
I can send further tcpdumps if required.
Thank you.
Please provide feedback.
Regards
Geert Stappers
