Configure Networking in Debian 12

/etc/network/interfacese

#iface enp1s0 inet dhcp              #indicates that interface take networking setting from dhcp server .

iface enp1s0 inet static            #add interface configuration manually   
address 10.10.10.1		    #IP address.
network 10.10.10.0                  #network address.
netmask 255.255.255.0              #subnet mask.
broadcast 10.10.10.255              #broadcast address.        
gateway 113.30.150.61               #is used to define the default gateway for the eth0 interface.
dns-nameservers 8.8.8.8.            #is the section where we define DNS servers.

Disable IPv6

Disable IPV6 if you do not need it.

#echo "net.ipv6.conf.all.disable_ipv6 = 1 >> /etc/sysctl.conf

Use bellow command to see results:

sysctl -p

Applying the Configuration

#sysctl restart ifup@enp1s0

Set Temporary addresses

#ifconfig eth0 192.168.1.4 netmask 255.255.255.0 broadcast 192.168.1.255

DNS

/etc/resolve.conf

domain homenetworking.net
search homenetworking.ir
nameserver 8.8.8.8
nameserver 8.8.4.4

Routing

List main route table

# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         113.30.150.254  0.0.0.0         UG    0      0        0 eth0
113.30.150.0    0.0.0.0         255.255.255.0   U     0      0        0 eth0
10.10.10.128    0.0.0.0         255.255.255.192 U     0      0        0 br0
127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        0 lo

Add/Delete Routes Temporary

# route add -host 10.10.10.129 dev eth1
# route add -net 10.10.10.128/26 dev eth0
# route add -net 172.16.10.1/24 gw 10.10.10.130
# route del -net 192.168.1.0/24 dev eth1
# route del default
# route add default gw 10.10.10.129 dev eth1