Dnsmasq versão 2.79 no MacOS 10.12.6 usando o Homebrew. Esta é a minha configuração do dnsmasq:
# Never forward plain names (without a dot or domain part)
domain-needed
# Never forward addresses in the non-routed address spaces.
bogus-priv
# If you want dnsmasq to listen for DHCP and DNS requests only on
# specified interfaces (and the loopback) give the name of the
# interface (eg eth0) here.
# Repeat the line for more than one interface.
interface=en4
# Always allocate the host with Ethernet address 11:22:33:44:55:66
# The IP address 192.168.0.60
<bunch of hosts>
# Do the same thing, but using the option name
dhcp-option=option:router,192.168.2.1
dhcp-option=option:ntp-server,192.168.2.1
dhcp-option=6,192.168.2.1,8.8.8.8,8.8.4.4
# Log lots of extra information about DHCP transactions.
log-dhcp
A parte importante é a parte das opções. Estou tentando conseguir que meus clientes DHCP obtenham três servidores DNS configurados: 192.168.2.1 e os dois Google. No entanto, isso é o que eu recebo quando eu sniff o tráfego DHCP vindo deste servidor:
---------------------------------------------------------------------------
TIME: 2018-05-21 17:40:37.454
IP: 192.168.2.1 (f6:5c:89:ca:e0:64) > 192.168.2.30 (0:50:b6:22:8e:6e)
OP: 2 (BOOTPREPLY)
HTYPE: 1 (Ethernet)
HLEN: 6
HOPS: 0
XID: 80916f1c
SECS: 0
FLAGS: 0
CIADDR: 0.0.0.0
YIADDR: 192.168.2.30
SIADDR: 192.168.2.1
GIADDR: 0.0.0.0
CHADDR: 00:50:b6:22:8e:6e:00:00:00:00:00:00:00:00:00:00
SNAME: .
FNAME: .
OPTION: 53 ( 1) DHCP message type 5 (DHCPACK)
OPTION: 54 ( 4) Server identifier 192.168.2.1
OPTION: 51 ( 4) IP address leasetime 43200 (12h)
OPTION: 58 ( 4) T1 21600 (6h)
OPTION: 59 ( 4) T2 37800 (10h30m)
OPTION: 1 ( 4) Subnet mask 255.255.255.0
OPTION: 28 ( 4) Broadcast address 192.168.2.255
OPTION: 3 ( 4) Routers 192.168.2.1
OPTION: 6 ( 4) DNS server 192.168.2.1
OPTION: 12 ( 8) Host name aimdroid
OPTION: 42 ( 4) NTP servers 192.168.2.1
---------------------------------------------------------------------------
Apenas um servidor DNS é relatado. O que está errado aqui?