DHCP Question Please

RouterOS Beginner Basics
1

Hi, I went to a new site today to do some bit’s. While I was there I went to the login page on winbox for an existing router onsite whilst I was waiting for the customer to see if he could get the password. However I logged in without ANY password and grabbed the config to have a look at later. The WAN was on a dhcp client from a BT hub. We connected some kit on the LAN side and let the router hand out via dhcp. We were given a 192.168.0.0/24 address and had internet etc. Looking at the DHCP pool however it looks like the default 88.x. How were we handed this address?

# jul/05/2022 11:53:40 by RouterOS 6.45.3
# software id = 601S-KQCH
#
# model = RB2011iL
# serial number = xxxxxx
/interface bridge
add admin-mac=xxxxxx auto-mac=no comment=defconf name=bridge
/interface list
add comment=defconf name=WAN
add comment=defconf name=LAN
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
/ip pool
add name=default-dhcp ranges=192.168.88.10-192.168.88.254
/ip dhcp-server
add address-pool=default-dhcp interface=bridge name=defconf
/interface bridge port
add bridge=bridge comment=defconf interface=ether2
add bridge=bridge comment=defconf interface=ether3
add bridge=bridge comment=defconf interface=ether4
add bridge=bridge comment=defconf interface=ether5
add bridge=bridge comment=defconf interface=ether6
add bridge=bridge comment=defconf interface=ether7
add bridge=bridge comment=defconf interface=ether8
add bridge=bridge comment=defconf interface=ether9
add bridge=bridge comment=defconf interface=ether10
/ip neighbor discovery-settings
set discover-interface-list=LAN
/interface list member
add comment=defconf interface=bridge list=LAN
add comment=defconf interface=ether1 list=WAN
/ip address
add address=192.168.0.1/24 comment=defconf interface=ether2 network=\
    192.168.0.0
/ip dhcp-client
add comment=defconf dhcp-options=hostname,clientid disabled=no interface=\
    ether1
/ip dhcp-server network
add address=192.168.0.0/24 comment=defconf gateway=192.168.0.1 netmask=24
/ip dns
set allow-remote-requests=yes
/ip dns static
add address=192.168.0.1 comment=defconf name=router.lan
/ip firewall filter
add action=accept chain=input comment=\
    "defconf: accept established,related,untracked" connection-state=\
    established,related,untracked
add action=drop chain=input comment="defconf: drop invalid" connection-state=\
    invalid
add action=accept chain=input comment="defconf: accept ICMP" protocol=icmp
add action=accept chain=input comment=\
    "defconf: accept to local loopback (for CAPsMAN)" dst-address=127.0.0.1
add action=drop chain=input comment="defconf: drop all not coming from LAN" \
    in-interface-list=!LAN
add action=accept chain=forward comment="defconf: accept in ipsec policy" \
    ipsec-policy=in,ipsec
add action=accept chain=forward comment="defconf: accept out ipsec policy" \
    ipsec-policy=out,ipsec
add action=fasttrack-connection chain=forward comment="defconf: fasttrack" \
    connection-state=established,related
add action=accept chain=forward comment=\
    "defconf: accept established,related, untracked" connection-state=\
    established,related,untracked
add action=drop chain=forward comment="defconf: drop invalid" \
    connection-state=invalid
add action=drop chain=forward comment=\
    "defconf: drop all from WAN not DSTNATed" connection-nat-state=!dstnat \
    connection-state=new in-interface-list=WAN
/ip firewall nat
add action=masquerade chain=srcnat comment="defconf: masquerade" \
    ipsec-policy=out,none out-interface-list=WAN
/system clock
set time-zone-name=Europe/London
/tool mac-server
set allowed-interface-list=LAN
/tool mac-server mac-winbox
set allowed-interface-list=LAN
2

Well for starters, your DHCP server network is 192.168.0.0/24 and the DHCP server is not specifying which IP Pool to use.

3

Where is that please?

/ip pool
add name=default-dhcp ranges=192.168.88.10-192.168.88.254
/ip dhcp-server
add address-pool=default-dhcp interface=bridge name=defconf

I can see the DHCP network defined

/ip dhcp-server network
add address=192.168.0.0/24 comment=defconf gateway=192.168.0.1 netmask=24

But how will it know what addresses to use or will it just do the whole /24?

4

That’s what I get for trying to read a config when I am dead tired.
I missed that the pool was specified, but the IP for the router is specified as 192.168.0.1/24 as is the gateway. Essentially everywhere in the config where an IP address is specified it is in the 192.168.0.0/24 net except the IP pool for the DHCP server.
Also, the router IP address is specified as ether2 and as I understand it, that should be on the bridge (I’m not good with bridges).

5

That’s the bit I found confusing, looks like the wrong address for the pool but I was correctly handed a 192.168.0.0/24 address but not sure how.

6

/ip address
add address=192.168.0.1/24 comment=defconf interface=ether2 network=
192.168.0.0

To this
/ip address
add address=192.168.0.1/24 comment=defconf interface=bridge network=
192.168.0.0