ifconfig
eth0      Link encap:Ethernet  HWaddr 00:e0:b6:05:7a:93
          inet addr:192.168.1.1  Bcast:0.0.0.0  Mask:255.255.0.0
          inet6 addr: fe80::2e0:b6ff:fe05:7a93/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:25900177 errors:0 dropped:0 overruns:0 frame:0
          TX packets:34526150 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1051279369 (1.0 GB)  TX bytes:691316784 (691.3 MB)
eth4      Link encap:Ethernet  HWaddr 00:24:21:b6:78:86
          inet addr:172.16.1.1  Bcast:0.0.0.0  Mask:255.255.0.0
          inet6 addr: fe80::224:21ff:feb6:7886/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:34915468 errors:0 dropped:0 overruns:0 frame:0
          TX packets:25619138 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1162053437 (1.1 GB)  TX bytes:1104174378 (1.1 GB)
          Interrupt:43 Base address:0x2000
eth0.150  Link encap:Ethernet  HWaddr 00:e0:b6:05:7a:93
          inet addr:10.0.150.250  Bcast:0.0.0.0  Mask:255.255.255.0
          inet6 addr: fe80::2e0:b6ff:fe05:7a93/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4404 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:434222 (434.2 KB)
eth0.171  Link encap:Ethernet  HWaddr 00:e0:b6:05:7a:93
          inet addr:10.0.171.250  Bcast:0.0.0.0  Mask:255.255.255.0
          inet6 addr: fe80::2e0:b6ff:fe05:7a93/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4405 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:434287 (434.2 KB)
eth0.172  Link encap:Ethernet  HWaddr 00:e0:b6:05:7a:93
          inet addr:10.0.172.250  Bcast:0.0.0.0  Mask:255.255.255.0
          inet6 addr: fe80::2e0:b6ff:fe05:7a93/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4404 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:434222 (434.2 KB)

dhcpd.conf
shared-network t {
min-lease-time 36000;
default-lease-time 43200;
max-lease-time 86400;
option domain-name "example.org";
one-lease-per-client true;
subnet 192.168.0.0 netmask 255.255.0.0 {
        option routers 192.168.1.1;
        #deny unknown-clients;
        option domain-name-servers 192.168.1.1;
        server-identifier 192.168.1.1;
        pool {
                range 192.168.20.10 192.168.20.200;
                allow members of "ubnt-modems";
        }
}
subnet 172.16.0.0 netmask 255.255.0.0 {
        range 172.16.10.10 172.16.10.200;
        option routers 172.16.1.1;
        allow unknown-clients;
        min-lease-time 30;
        default-lease-time 30;
        max-lease-time 30;
        authoritative;
        option domain-name-servers 172.16.1.1;
        server-identifier 172.16.1.1;
}
}
shared-network su{
min-lease-time 36000;
default-lease-time 43200;
max-lease-time 86400;
option domain-name "example.org";
one-lease-per-client true;
include "/etc/dhcp/subnets-auto.conf";
}

subnets-auto.conf

subnet 10.0.171.0 netmask 255.255.255.0 {
    option routers 10.0.171.250;
    option domain-name-servers 10.0.171.250;
    pool {
        deny unknown-clients;
        range 10.0.171.1 10.0.171.126;
    }
    pool {
        range 10.0.171.127 10.0.171.200;
        allow unknown-clients;
        min-lease-time 20;
        default-lease-time 20;
        max-lease-time 20;
    }
}
subnet 10.0.172.0 netmask 255.255.255.0 {
    option routers 10.0.172.250;
    option domain-name-servers 10.0.172.250;
    pool {
        deny unknown-clients;
        range 10.0.172.1 10.0.172.126;
    }
    pool {
        range 10.0.172.127 10.0.172.200;
        allow unknown-clients;
        min-lease-time 20;
        default-lease-time 20;
        max-lease-time 20;
    }
}
subnet 10.0.173.0 netmask 255.255.255.0 {
    option routers 10.0.173.250;
    option domain-name-servers 10.0.173.250;
    pool {
        deny unknown-clients;
        range 10.0.173.1 10.0.173.126;
    }
    pool {
        range 10.0.173.127 10.0.173.200;
        allow unknown-clients;
        min-lease-time 20;
        default-lease-time 20;
        max-lease-time 20;
    }
        max-lease-time 20;
    }
}
subnet 10.0.174.0 netmask 255.255.255.0 {
    option routers 10.0.174.250;
    option domain-name-servers 10.0.174.250;
    pool {
        deny unknown-clients;
        range 10.0.174.1 10.0.174.126;
    }
    pool {
        range 10.0.174.127 10.0.174.200;
        allow unknown-clients;
        min-lease-time 20;
        default-lease-time 20;
        max-lease-time 20;
    }
}

и лог


Nov 13 14:14:58 example dhcpd: Multiple interfaces match the same shared network: eth0 eth4
Nov 13 14:14:58 example dhcpd: Multiple interfaces match the same shared network: eth0.171 eth0.172
Nov 13 14:14:58 example dhcpd: Multiple interfaces match the same shared network: eth0.171 eth0.173
Nov 13 14:14:58 example dhcpd: Multiple interfaces match the same shared network: eth0.171 eth0.174
Nov 13 14:14:58 example dhcpd: Multiple interfaces match the same shared network: eth0.171 eth0.175
Nov 13 14:14:58 example dhcpd: Multiple interfaces match the same shared network: eth0.171 eth0.176
Nov 13 14:14:58 example dhcpd: Multiple interfaces match the same shared network: eth0.171 eth0.177
Nov 13 14:14:58 example dhcpd: Multiple interfaces match the same shared network: eth0.171 eth0.178
Nov 13 14:14:58 example dhcpd: Multiple interfaces match the same shared network: eth0.171 eth0.150
Nov 13 14:14:58 example dhcpd: Multiple interfaces match the same shared network: eth0.171 eth0.201