Posted: Tue Jun 14, 2022 15:38 Post subject: [SOLVED] DHCP, VMs, switch ports, and Proxmox
kernel: Linux 4.4.241 #1327 SMP Tue Nov 3 09:06:16 +03 2020 armv7l
build: DD-WRT v3.0-r44715 std (11/03/20)
hardware: Asus RT-AC5300
Howdy, folks. I'm seeing some strange behavior from the DHCP server servicing my embedded switch. I have a Proxmox server attached to a switch port. Proxmox is configured for bridging with bridge IP assigned via DHCP. VMs mapped to that bridge have unique MAC addresses and are requesting addresses via DHCP also.
As the VMs boot the router is reassigning the same LAN IP address to each VM despite each of them having a distinct MAC. There's nothing in the logs which suggests, for instance, that the initial DHCP request is going out with the bridge MAC and thus that's the source of the re-used IP. Generally, there's nothing in the router logs nor in Proxmox logs to suggest that either is unhappy with the DHCP process though clearly the VMs end up not being happy about the situation.
I dug into STP settings and didn't see anything special that needed to be set on the router to allow for multiple MAC addresses on a single switch port.
VLANs are enable neither on the router nor on the Proxmox server. I have the option to store MAC addresses in NVRAM turned off because it seems to prevent the WAN port on the router from getting a DHCP address from ISP for some undetermined region.
Any thoughts? At this point I'm considering just virtualizing the firewall/router as a work-around because this has me pretty baffled.
Joined: 18 Mar 2014 Posts: 12917 Location: Netherlands
Posted: Tue Jun 14, 2022 15:45 Post subject:
Welcome to the forum.
You are using an old and outdated build (not that I think that that is the problem but you never know)
Current build is 49197
See the forum guidelines with helpful pointers about how to research your router, where and what firmware to download, where and how to post and many other helpful tips:
https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=324087
Joined: 31 Jul 2021 Posts: 2146 Location: All over YOUR webs
Posted: Tue Jun 14, 2022 19:04 Post subject:
marquin wrote:
New firmware hasn't resolved.
I'll have to "schedule some downtime" for the hand re-configure as my config is fairly complicated and has evolved over quite some time.
I'll post up here with status/resolution as things develop.
Sorry to read that
I forgot to mention you could have dumped the config to text file for reference, and grabbing file to desktop or your preferred location.
Code:
nvram show > /tmp/sombkp-id.txt
The above tip is now included in the backup tab within the routers built in help pages as well since Im giving the English strings a much needed once over, I added new stuff.
Posted: Sat Jun 18, 2022 17:32 Post subject: Solved! /etc/machine-id!
Solved!
The machines were deployed from VM template and had the same /etc/machine-id value. The DHCP server was using machine-id/client-id over the MAC address when assigning IPs and thus the overlaps.
FWIW, I noticed this by looking at dd-wrt's /tmp/dnsmasq.leases file while rebooting the VMs and then looking up the meaning of the data in each field.
Thanks for the help, folks! So glad this is resolved and I can continue the automation I'm working on!
