Proxmox host has no internet connection, but VM's do

[realTyr]

HI!

Wen't to go do some updates on the proxmox host when I noticed the host itself seems to have no public internet connection, can't ping anything etc. However my windows VM (only thing I've set up atm) has a completely fine wired internet connection- it seems like most of my configs are correct, and I took my DNS right from my routers defaults so hoping someone can give some pointers of where to go from here! Total proxmox noob, just set everything up for the first time yesterday. Enterprise stuff has been removed from the respository.

 

[vshab]

What's your network topology? Have you tried disabling firewall with pve-firewall stop? (wiki link)

 

[Frenzy0897]

I was just about to destroy my proxmox lab and start all over again until I saw your question. Maybe we can help each other? I'm new to Proxmox as well and having this same problem as well: My proxmox host has no Internet access, yet my VMs and containers (pfSense, Ubuntu Servers, Docker and Portainer) all have Internet access.

Below are the things I've checked so far along with my results so you can compare. Hopefully we can resolve this issue:

0) I ssh into Proxmox

ssh root@192.168.100.3

1) Ping Google (unsuccessful)

ping google.com

2) Ping 8.8.8.8 (unsuccessful)

ping 8.8.8.8

3) Ping my ISP's internet router (success!)

ping 192.168.100.1

4) Traceroute (All "***", from 1 to 30)

traceroute 8.8.8.8

5) Nslookup (REFUSED)

nslookup 8.8.8.8 #** server can't find 8.8.8.8.in-addr.arpa: REFUSED

6) nslookup (REFUSED)

nslookup google.com
Server:        192.168.100.1
Address:    192.168.100.1#53

** server can't find google.com: REFUSED

7) ip route

ip route
default via 192.168.100.1 dev vmbr0 proto kernel onlink
10.10.1.0/24 dev vmbr1 proto kernel scope link src 10.10.1.0
192.168.100.0/24 dev vmbr0 proto kernel scope link src 192.168.100.100

8) DNS config

cat /etc/resolv.conf
nameserver 192.168.100.1
nameserver 8.8.8.8

9) I changed my Proxmox host IP to 192.168.100.100

10) Hosts lookup table

cat /etc/hosts
127.0.0.1 localhost.localdomain localhost
192.168.100.100 lab.local lab

11) Interfaces

cat /etc/network/interfaces
auto lo
iface lo inet loopback

iface enp0s31f6 inet manual

auto vmbr0
iface vmbr0 inet static
    address 192.168.100.100/24
    gateway 192.168.100.1
    bridge-ports enp0s31f6
    bridge-stp off
    bridge-fd 0

iface wlp4s0 inet manual

auto vmbr1
iface vmbr1 inet static
    address 10.10.1.0/24
    bridge-ports none
    bridge-stp off
    bridge-fd 0
    bridge-vlan-aware yes
    bridge-vids 2-4094
#LAB LAN

source /etc/network/interfaces.d/*

12) Proxmox firewall status

pve-firewall status # Status: enabled/running
cat /etc/pve/firewall/cluster.fw # (enable: 1)

Note: there were no firewall rules in my cluster.fw

13) Firewall rules in output chain related to proxmox 192.168.100.100

iptables -L OUTPUT -v -n | grep '192.168.100.100' # no results found
iptables -L -v -n # Lots of rules but can't figure it out yet

14) My ISP's Internet router's DHCP range is from 192.168.100.2 to 192.168.100.254 and no other device is using my proxmox IP (192.168.100.100)

15) I'm carefully going through Dunuin's comment from another post:

What does your network configuration look like (cat /etc/network/interfaces, cat /etc/hosts, cat /etc/resolv.conf)? Did you make sure the gateway and DNS server is setup correctly?
When guests can go online but the host not, its usually either:
1.) wrong gateway
2.) wrong DNS server
3.) double use of IPs, IP already used by another host
4.) host got 2 IPs in the same subnet
5.) using a IP of a wrong subnet
6.) bad firewall rules

EDIT: 16) When i checked the DNS on my laptop, I get a different nameserver

nameserver 127.0.0.53
options edns0 trust-ad
search .

 

[vshab]

My proxmox host has no Internet access, yet my VMs and containers (pfSense, Ubuntu Servers, Docker and Portainer) all have Internet access.

Do these VMs and containers use DHCP provided IP addresses? Maybe your router doesn't route traffic for hosts that don't have valid DHCP lease?

 

[Frenzy0897]

Do these VMs and containers use DHCP provided IP addresses? Maybe your router doesn't route traffic for hosts that don't have valid DHCP lease?

Yes they do. I have a pfSense VM in Proxmox that provides DHCP to three VLANs in Proxmox and all the VMs in these VLANs have Internet access.

EDIT:

Maybe your router doesn't route traffic for hosts that don't have valid DHCP lease?

I think you are quite correct. I was wondering the same thing. I was thinking about reserving the Proxmox IP address in the ISP's router but I read in note in the router that said you can reserve addresses that were assigned an IP address from DHCP, so i did not bother to try. What should i do? A bit of a long stretch but I was thinking about connecting to my router another physical hardware device with pfsense on it and maybe i can get it working that way

 

[Frenzy0897]

@vshab My Proxmox host finally has internet access now and updated successfully. Thank you very much for pointing me in the right direction!

You were correct. My ISP's router was not providing Internet access "for hosts that don't have valid DHCP lease".

I fixed it by making a backup copy of the interfaces file, changed my Proxmox host from static to dhcp, restarted the network service, successfully pinged 8.8.8.8, wrote down my new IP address, restored my back up copy of the interface file using my new static IP address, restarted the network service again and everything worked perfectly again. I then saved this IP address in my ISP's router under the DHCP Static IP Configuration.

(Perform these steps from Proxmox machine, not the Proxmox Web Interface)

Backup your interfaces file

cp /etc/network/interfaces /etc/network/interfaces.backup

Modify interfaces file for DHCP

nano /etc/network/interfaces


...
auto vmbr0
iface vmbr0 inet dhcp
        bridge-ports enp0s31f6
        bridge-stp off
        bridge-fd 0
...

Restart networking service

systemctl restart networking

Check for Internet connectivity

ping 8.8.8.8 # success!

Note the new IP

ip a # 192.168.100.206

Restore interfaces file with new IP

cp /etc/network/interfaces /etc/network/interfaces.old
cp /etc/network/interfaces.backup /etc/network/interfaces
nano /etc/network/interfaces


...
auto vmbr0
iface vmbr0 inet static
        address 192.168.100.206/24
        gateway 192.168.100.1
        dns-nameservers 8.8.8.8 8.8.4.4
        bridge-ports enp0s31f6
        bridge-stp off
        bridge-fd 0
...

Restart networking service

systemctl restart networking

Check for Internet connectivity

ping 8.8.8.8 # success!
ip route # default via 192.168.100.1 dev vmbr0 ...