Interface arp'able but not pingable

[forty-2]

Hello -
I have 3 devices on a ProxMox VLAN

• a linux machine
• a windows machine
• an OpenWRT instance (latest build as of 2 days ago)

OpenWRT has 2 interfaces & corresponding devices:

• lan0, on the VLAN, static IP, dhcp server
• lan2, on my main network, dhcp client

on the VLAN I can ping the machines from each other, and see the OpenWRT lan0(eth0) via arp -a, but it will not return a ping. I do however see dhcp requests & acks in the log. No problems getting to it through lan2(eth2).

It's a bog simple config; no zones, no routes, firewall set to accept.

Any ideas on where to start troubleshooting this would be appreciated.
thanks!
Paul

[brada4]

Maybe cables are crossed. arp responses will leak with default sysctls while ip responses will follow correct subnet routes.

[forty-2]

hmm... good to know. It's all Virtual Machines on ProxMox, and I've triple checked that all the devices are tagged on the same VLAN; that's all the 'cabling' in question.

[brada4]

so you tagged dhcp client and server in same vlan?

Please connect to your OpenWrt device using ssh and copy the output of the following commands and post it here using the "Preformatted text </> " button:

Remember to redact passwords, VPN keys, MAC addresses and any public IP addresses you may have:

ubus call system board
cat /etc/config/network
cat /etc/config/dhcp
cat /etc/config/firewall

[forty-2]

no, sorry, only lan0 is on the vlan running the dhcp server.
thanks for the assist

system board:

{
        "kernel": "6.6.104",
        "hostname": "OpenWrt",
        "system": "Common KVM processor",
        "model": "QEMU Standard PC (i440FX + PIIX, 1996)",
        "board_name": "qemu-standard-pc-i440fx-piix-1996",
        "rootfs_type": "ext4",
        "release": {
                "distribution": "OpenWrt",
                "version": "24.10.3",
                "revision": "r28872-daca7c049b",
                "target": "x86/64",
                "description": "OpenWrt 24.10.3 r28872-daca7c049b",
                "builddate": "1758316778"
        }
}

network

config interface 'loopback'
        option device 'lo'
        option proto 'static'
        option ipaddr '127.0.0.1'
        option netmask '255.0.0.0'

config globals 'globals'
        option ula_prefix 'fdde:2264:c224::/48'
        option packet_steering '0'

config device
        option name 'eth2'
        option ipv6 '0'

config interface 'lan2'
        option proto 'dhcp'
        option device 'eth2'
        option defaultroute '0'

config device
        option name 'eth0'

config interface 'lan0'
        option proto 'static'
        option device 'eth0'
        option ipaddr '192.168.49.1'
        option netmask '255.255.255.0'

dhcp

config dnsmasq
        option domainneeded '1'
        option boguspriv '1'
        option filterwin2k '0'
        option localise_queries '1'
        option rebind_protection '1'
        option rebind_localhost '1'
        option local '/lan/'
        option domain 'lan'
        option expandhosts '1'
        option nonegcache '0'
        option cachesize '1000'
        option authoritative '1'
        option readethers '1'
        option leasefile '/tmp/dhcp.leases'
        option resolvfile '/tmp/resolv.conf.d/resolv.conf.auto'
        option nonwildcard '1'
        option localservice '1'
        option ednspacket_max '1232'
        option filter_aaaa '0'
        option filter_a '0'

config odhcpd 'odhcpd'
        option maindhcp '0'
        option leasefile '/tmp/hosts/odhcpd'
        option leasetrigger '/usr/sbin/odhcpd-update'
        option loglevel '4'

config dhcp 'lan0'
        option interface 'lan0'
        option start '100'
        option limit '150'
        option leasetime '12h'

firewall

config defaults
        option input 'ACCEPT'
        option output 'ACCEPT'
        option forward 'REJECT'
        option synflood_protect '1'

[brada4]

You have to check with proxmox documentation why bridge is not forwarding.

[forty-2]

yeah, I'll dig deeper into that - the fact that the other two machines on the bridge can ping each other led me to believe that wasn't the issue.
So the config looks OK?

[brada4]

Interfaces are configured exactly as you wanted, there is no magic to add inside the vm.