Network access (ssh and ping) lost when logged out

Glubbdrubb

6/7/23, 10:00 AM

My host (5.4.0-97-generic Ubuntu 20.04.3 LTS) responds to ping and allows ssh when my user is logged in, remotely or locally. However, if I restart or log out all user sessions, I lose ssh access and it no longer responds to ICMP requests.

This behaviour started a few weeks ago after I remotely updated and restarted the host. I used to be able to login without any users logged in. I have since come back to the office and installed more updates, but the problem persists.

My firewall is set to public mode (I have a public IP) and explicitly allows SSH.

I tried specifying the IP settings (auto settings) as answered in this question but it didn't work after restarting.

# interfaces(5) file used by ifup(8) and ifdown(8)
auto eth0
iface eth0 inet dhcp

My public IP is semi-static.

Here is the output of /etc/netplan/*.yaml

# Let NetworkManager manage all devices on this system
network:
  version: 2
  renderer: NetworkManager

Here's what Network Manager has:

0 + 0

network-manager

networking

Thomas Aichinger

6/8/23, 4:37 PM

can you show us your netplan configuration. /etc/netplan/*.yaml

Glubbdrubb

6/9/23, 11:58 AM

I added what you wanted :-)

Thomas Aichinger

6/9/23, 11:23 PM

I recommend to stop network manager and set in place a real netplan yaml file. Here you can find some examples https://wiki.ubuntuusers.de/Netplan/

Glubbdrubb

6/10/23, 9:31 AM

That did the trick. Would you like to answer the question? Or should I answer it myself with the netplan yaml I used? I am disappointed that NetworkManager changed it's behaviour after an update though.

Score:1

Ubuntu

Thomas Aichinger

6/10/23, 10:19 AM

I would recommend to use a netplan yaml file with renderer networkd.

Here is the default after installation.

01-netplan.yaml

# This file describes the network interfaces available on your system
# For more information, see netplan(5).
network:
  version: 2
  renderer: networkd
  ethernets:
    ens32:
      dhcp4: yes
      dhcp6: yes

0 + 0

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Network access (ssh and ping) lost when logged out

TH: การเข้าถึงเครือข่าย (ssh และ ping) หายไปเมื่อออกจากระบบ

RO: Accesul la rețea (ssh și ping) s-a pierdut la deconectare

RU: Доступ к сети (ssh и ping) потерян при выходе из системы

VI: Truy cập mạng (ssh và ping) bị mất khi đăng xuất

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