Unable to connect Proxmox via Ethernet after installation

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roti

New Member
May 2, 2024
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Hi everyone,
I've just installed Proxmox on an old laptop without any particular expectation or need, just to fiddle with it.

My problem is that the Ethernet connection doesn't work. I searched a bit on this forum and apparently it's something that happens frequently, but I tried all the options and none worked.

Important: my router IP is 192.168.1.254, so I tought I had to edit /etc/network/interfaces with this IP (before was like 192.168.1.1). I'm sorry but I'm just learning and I don't understand networks so well yet.

Anyway, I hope there's someone that can help me. Here's something that may be useful to understand the problem.

cat /etc/network/interface output:

Bash: 
auto lo

iface lo inet loopback

iface eth0 inet manual

auto vmbr0

iface vmbr0 inet static

address 192.168.1.250/24

gateway 192.168.100.251

bridge-ports etho

bridge-stp off

bridge-fd 0

iface wlp16s0 inet manual

source /etc/network/interfaces.d/*

ip a output:
Bash: 
1: 10: <LOOPBACK, UP, LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
   link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
   Inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6:: 1/128 scope host noprefixroute
       valid_lft forever preferred_lft forever

2: ethe: <BROADCAST, MULTICAST, UP, LOWER_UP> mtu 1500 qdisc pfifo_fast master vmbre state UP group default qlen 1000
      link/ether 00:17:08:41:48:6b brd ffffffffffff
3: wlp16s0: <BROADCAST, MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
      link/ether 00:18:de:a2:6d:03 brd ffffffffffff
4: vmbre: <BROADCAST, MULTICAST, UP, LOWER_UP> mtu 1580 qdisc noqueue state UP group default qlen 1000
      link/ether 00:17:08:41:48:6b brd ffffffffffff
      inet 192.168.1.250/24 scope global vmbre
           valid_lft forever preferred_lft forever
      inet6 fe80::217:8ff:fe41:4a6b/64 scope link
           valid_lft forever preferred_lft forever

lspci | grep 'Ethernet' output:
Bash: 
02:08.0 Ethernet controller: Broadcom Inc. and subsidiaries BCM4401-B0 100Base-TX (rev 02)

Thanks in advance.
 
Last edited:
roti said:
address 192.168.1.250/24
gateway 192.168.100.251
Click to expand...
This can not work.

For traffic to be able to leave your network you need a gateway inside of this very network. ".100." and ".1." are two different networks (as long as /24 is specified.)

Find out what your actual gateway is. This is essential.

If - for example, I can not know - it is ".100.251" as you stated, you may try "address 192.168.100.250/24" for this computer. (If this address is unused.)
 
UdoB said:
This can not work.

For traffic to be able to leave your network you need a gateway inside of this very network. ".100." and ".1." are two different networks (as long as /24 is specified.)

Find out what your actual gateway is. This is essential.

If - for example, I can not know - it is ".100.251" as you stated, you may try "address 192.168.100.250/24" for this computer. (If this address is unused.)
Click to expand...
Hi, thanks for trying to help me.

First, sorry for spelling errors, I edited the question with vmbr0.

I find out that my default gateway is 192.168.1.254, so I changed /etc/network/interfaces in
Code: 
address: 192.168.1.27/24
gateway: 192.168.1.254

Is that right? I checked the address IP with nmap and it seemed unused.

Anyway, even doing this changes, internet doesn't work...
 
roti said:
Is that right?
Click to expand...
At least it is technically ok :-)
  1. did you activate it? (Via ifrealod -a or by a reboot.) Does "ip a" confirm this?
  2. does a "ping" locally on that lan work? At least the device confirmed-to-be-the-router must work: ping 192.168.1.254
  3. routing can be confirmed by ip route show - the first line must show "default via 192.168.1.254"
  4. only then a ping to the outside can work. At first without DNS: ping 9.9.9.9 must work
  5. we did not talk about DNS yet. If configured correctly ping dns9.quad9.net can work now
 
UdoB said:
At least it is technically ok :)
  1. did you activate it? (Via ifrealod -a or by a reboot.) Does "ip a" confirm this?
  2. does a "ping" locally on that lan work? At least the device confirmed-to-be-the-router must work: ping 192.168.1.254
  3. routing can be confirmed by ip route show - the first line must show "default via 192.168.1.254"
  4. only then a ping to the outside can work. At first without DNS: ping 9.9.9.9 must work
  5. we did not talk about DNS yet. If configured correctly ping dns9.quad9.net can work now
Click to expand...
Thank you so much for your time.
Point 1 gives
Bash: 
1: 10: <LOOPBACK, UP, LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1888

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo

valid_lft forever preferred_lft forever

inet6:: 1/128 scope host nopref ixroute

valid_lft forever preferred_lft forever

2: eth0: <BROADCAST, MULTICAST, UP, LOWER_UP> mtu 1500 qdisc pfifo_fast master vmb0 state UP group default qlen 1000

link/ether 00:17:08:41:48:6b brd ff:ff:ff:ff:ff:ff : wlp1650: <BROADCAST, MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1806 3

link/ether 08:18:de:a2:6d:03 brd ffffffffffff

4: vmbr0: <BROADCAST, MULTICAST, UP, LOWER_UP> mtu 1588 qdisc noqueue state UP group default qlen 1000

link/ether 00:17:08:41:48:6b brd ffffffffffff inet 192.168.1.27/24 scope global vmbr0

valid_lft forever preferred_lft forever

inet6 fe80::217:8ff:fe41:4a6b/64 scope link valid_Ift forever preferred_ift

Point 2,3,4 gave the output you expected, but 5 didn't
Code: 
(temporary failure in name resolution)
 
Last edited:
There are still typos! You need to be more careful:
roti said:
2: eth0: <BROADCAST, MULTICAST, UP, LOWER_UP> mtu 1500 qdisc pfifo_fast master vmb0 state UP group default qlen 1000
Click to expand...
That "vmb0" ist just wrong!

Correct the typo, then again post the outputs of "cat /etc/network/interfaces; ifreload -a && ip a" ;-)
 
UdoB said:
There are still typos! You need to be more careful:

That "vmb0" ist just wrong!

Correct the typo, then again post the outputs of "cat /etc/network/interfaces; ifreload -a && ip a" ;-)
Click to expand...
Sorry, my fault. Posting photos instead of transcribing may be the solution.

Here you are:
 

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Okay :-)

My "5." was mentioning DNS. The officiall place to configure it is "<node> --> System --> DNS". What is shown there as "DNS server 1"? You can edit it to read 9.9.9.9.

At the end this setting can be verified via the command line with "cat /etc/resolv.conf" - it needs to show the same settings as entered in that dialog.

Now on the command line host google.com and finally ping google.com should work.
 
UdoB said:
Okay :)

My "5." was mentioning DNS. The officiall place to configure it is "<node> --> System --> DNS". What is shown there as "DNS server 1"? You can edit it to read 9.9.9.9.

At the end this setting can be verified via the command line with "cat /etc/resolv.conf" - it needs to show the same settings as entered in that dialog.

Now on the command line host google.com and finally ping google.com should work.
Click to expand...
Thanks a lot man, it worked. I wish you all the best.

One last thing: I can't connect to the web interface. Is that related to IPs or something?

EDIT: nevermind, I find out I had to edit also /etc/hosts.
 
Last edited:
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