## Interfaces

### Configure interface

`R(config)>interface <interface_name>`

`R(config-if)>ip address <ip_addr> <netmask>`

`R(config-if)>no shutdown`

### Loopback interfaces

`R(config)>interface loopback[number]`

`R(config)>ip address <ip_addr> <netmask>`

`R(config)>no shutdown`

### Show interface

`R#> show interface <interface_name>`

`R#> show ip interface brief`

## OSPF

### Declare OSPF

`R(config)> router ospf 1`

`R(config-router)> network <network_ip> <rev_mask> area <area_number>`

### Show interface details

`R#>show ip ospf interface <interface_name>`

### Routes resume

`R#> show ip ospf neighbor`

`R#> show ip ospf database`

`R#> show ip route ospf`

### MD5 authentication (for one interface)

`R(config)> interface <interface_name>`

`R(config)> ip ospf authentication message-digest`

`R(config)> ip ospf message-digest-key <key_id> md5 <password>`

## TFTP

### Upload configuration to server

`R#> copy running-config tftp:`

### Download configuration from server

`R#> copy tftp running-config:`