When working with Debian Sid (Unstable), you might accidentally delete critical system files like /etc/hosts. Unlike regular packages, the hosts file doesn't belong to any specific Debian package, which explains why dpkg -S /etc/hosts returns no results.

The default Debian hosts file typically contains these essential entries:

127.0.0.1       localhost
127.0.1.1       your-hostname

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Method 1: Manual Recreation

Create a new file with nano or vim:

sudo nano /etc/hosts

Then paste the default content shown above, replacing your-hostname with your actual hostname (check with hostname command).

Method 2: Using base-files Package

While /etc/hosts isn't owned by a package, the template exists in base-files:

sudo apt install --reinstall base-files
sudo cp /usr/share/base-files/hosts /etc/hosts

Method 3: NetworkManager Fallback

If using NetworkManager, it can generate a basic hosts file:

sudo service network-manager restart
sudo dhclient

After restoration, verify with:

cat /etc/hosts
ping -c 1 localhost
getent hosts

For systems with custom configurations or containers, you might need additional entries. Always test network connectivity after modifying /etc/hosts.

Consider these best practices:

• Backup important config files: sudo cp /etc/hosts /etc/hosts.bak
• Use version control for system configurations
• Implement configuration management tools like Ansible

For development environments, you might want dynamic hosts management. Here's a Python script example:

#!/usr/bin/env python3
import socket

def restore_default_hosts(hostname):
    template = f"""127.0.0.1       localhost
127.0.1.1       {hostname}

# IPv6 configuration
::1     localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
"""
    with open('/etc/hosts', 'w') as f:
        f.write(template)

if __name__ == '__main__':
    restore_default_hosts(socket.gethostname())

Save as restore_hosts.py and run with sudo python3 restore_hosts.py.

---

When you run dpkg -S /etc/hosts on Debian Sid and get no results, it's because the /etc/hosts file isn't actually owned by any specific package in Debian's packaging system. This file is typically generated during system installation.

The closest official source is the base-files package which contains a template. You can extract it with:

apt download base-files
dpkg -x base-files_*.deb /tmp/base-files
cat /tmp/base-files/etc/hosts

Here's the standard minimal configuration:

127.0.0.1       localhost
127.0.1.1       yourhostname

# The following lines are desirable for IPv6 capable hosts
::1             localhost ip6-localhost ip6-loopback
ff02::1         ip6-allnodes
ff02::2         ip6-allrouters

Method 1: Reinstall base-files (won't overwrite existing configs)

sudo apt-get --reinstall install base-files

Method 2: Create manually with hostname detection

sudo bash -c 'cat > /etc/hosts << EOF
127.0.0.1       localhost
127.0.1.1       $(hostname)

# IPv6
::1             localhost ip6-localhost ip6-loopback
ff02::1         ip6-allnodes
ff02::2         ip6-allrouters
EOF'

After restoring, verify with:

ping -c 1 localhost
hostname --fqdn

For systems with special network requirements, you might need additional entries. The Debian Reference recommends keeping the IPv4 localhost line exactly as shown for compatibility.