DHCP server offers new IP address for existing lease

RouterOS General
1

Hi.

Playing with virtual machines and i’m tired of finding new ip address of vm, adding it ssh known_hosts. I’m using usb-ethernet adapter and passthrough it to guest os on my pc. So every time i get a working internet (with the same mac address of course) without messing with bridge, nat, etc on host pc.

Steps to reproduce:

  1. install stable debian 9 in vm.
  2. reboot - new ip.
  3. don’t even touch any configs inside guest os, just reboot - new ip.

RouterOS v6.42.1 (stable) on 951G-2HnD

Am i getting it right that debian sends “release” message on shutdown?

Added new rule to system/logging with topic=dhcp and action=disk.

May/31/2018 21:52:23 dhcp,debug,packet default received release with id 2431802484 from 192.168.88.187
May/31/2018 21:52:23 dhcp,debug,packet     ciaddr = 192.168.88.187
May/31/2018 21:52:23 dhcp,debug,packet     chaddr = 00:0E:C6:81:82:11
May/31/2018 21:52:23 dhcp,debug,packet     Msg-Type = release
May/31/2018 21:52:23 dhcp,debug,packet     Server-Id = 192.168.88.1
May/31/2018 21:52:23 dhcp,debug,packet     Host-Name = "testdeb"
May/31/2018 21:52:23 dhcp,info default deassigned 192.168.88.187 from 00:0E:C6:81:82:11
May/31/2018 21:52:42 dhcp,debug,packet default received discover with id 891864155 from 0.0.0.0
May/31/2018 21:52:42 dhcp,debug,packet     secs = 7
May/31/2018 21:52:42 dhcp,debug,packet     ciaddr = 0.0.0.0
May/31/2018 21:52:42 dhcp,debug,packet     chaddr = 00:0E:C6:81:82:11
May/31/2018 21:52:42 dhcp,debug,packet     Msg-Type = discover
May/31/2018 21:52:42 dhcp,debug,packet     Address-Request = 192.168.88.187
May/31/2018 21:52:42 dhcp,debug,packet     Host-Name = "testdeb"
May/31/2018 21:52:42 dhcp,debug,packet     Parameter-List = Subnet-Mask,Broadcast-Address,Unknown(2),Router,Domain-Name,Domain-Server,Domain-Search,Host-Name,NETBIOS-Name-Server,NETBIOS-Scope,Interface-MTU,Classless-Route,NTP-Server
May/31/2018 21:52:42 dhcp,info default deassigned 192.168.88.188 from 00:0E:C6:81:82:11
May/31/2018 21:52:42 dhcp,debug,packet default sending offer with id 891864155 to 192.168.88.188
May/31/2018 21:52:42 dhcp,debug,packet     ciaddr = 0.0.0.0
May/31/2018 21:52:42 dhcp,debug,packet     yiaddr = 192.168.88.188
May/31/2018 21:52:42 dhcp,debug,packet     siaddr = 192.168.88.1
May/31/2018 21:52:42 dhcp,debug,packet     chaddr = 00:0E:C6:81:82:11
May/31/2018 21:52:42 dhcp,debug,packet     Msg-Type = offer
May/31/2018 21:52:42 dhcp,debug,packet     Server-Id = 192.168.88.1
May/31/2018 21:52:42 dhcp,debug,packet     Address-Time = 31536600
May/31/2018 21:52:42 dhcp,debug,packet     Subnet-Mask = 255.255.255.0
May/31/2018 21:52:42 dhcp,debug,packet     Router = 192.168.88.1
May/31/2018 21:52:42 dhcp,debug,packet     Domain-Server = 192.168.88.1
May/31/2018 21:52:42 dhcp,debug,packet default received request with id 891864155 from 0.0.0.0
May/31/2018 21:52:42 dhcp,debug,packet     secs = 7
May/31/2018 21:52:42 dhcp,debug,packet     ciaddr = 0.0.0.0
May/31/2018 21:52:42 dhcp,debug,packet     chaddr = 00:0E:C6:81:82:11
May/31/2018 21:52:42 dhcp,debug,packet     Msg-Type = request
May/31/2018 21:52:42 dhcp,debug,packet     Server-Id = 192.168.88.1
May/31/2018 21:52:42 dhcp,debug,packet     Address-Request = 192.168.88.188
May/31/2018 21:52:42 dhcp,debug,packet     Host-Name = "testdeb"
May/31/2018 21:52:42 dhcp,debug,packet     Parameter-List = Subnet-Mask,Broadcast-Address,Unknown(2),Router,Domain-Name,Domain-Server,Domain-Search,Host-Name,NETBIOS-Name-Server,NETBIOS-Scope,Interface-MTU,Classless-Route,NTP-Server
May/31/2018 21:52:42 dhcp,info default assigned 192.168.88.188 to 00:0E:C6:81:82:11
May/31/2018 21:52:42 dhcp,debug,packet default sending ack with id 891864155 to 192.168.88.188
May/31/2018 21:52:42 dhcp,debug,packet     ciaddr = 0.0.0.0
May/31/2018 21:52:42 dhcp,debug,packet     yiaddr = 192.168.88.188
May/31/2018 21:52:42 dhcp,debug,packet     siaddr = 192.168.88.1
May/31/2018 21:52:42 dhcp,debug,packet     chaddr = 00:0E:C6:81:82:11
May/31/2018 21:52:42 dhcp,debug,packet     Msg-Type = ack
May/31/2018 21:52:42 dhcp,debug,packet     Server-Id = 192.168.88.1
May/31/2018 21:52:42 dhcp,debug,packet     Address-Time = 31536600
May/31/2018 21:52:42 dhcp,debug,packet     Subnet-Mask = 255.255.255.0
May/31/2018 21:52:42 dhcp,debug,packet     Router = 192.168.88.1
May/31/2018 21:52:42 dhcp,debug,packet     Domain-Server = 192.168.88.1
2

There were DHCP issues in 6.42.1, upgrade to latest, 6.42.3 and test again