> For the complete documentation index, see [llms.txt](https://cleberjamaral.gitbook.io/mind/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cleberjamaral.gitbook.io/mind/knowledge/it/networks.md).

# networks

### network configuration

* using ip `$ ip a`
* using ifconfig `$ ifconfig`
* using nmcli (networkmanager) `$ nmcli device show`

### Enable/disable interfaces

* using ifdown e ifup # `ifdown eth0 && ifup eth0`
* using ip `# ip link set dev eth0 down && ip link set dev eth0 up`
* using networking (deprecated) `# service networking restart`
* using network restart `# /etc/init.d/network restart`
* using ifconfig `# ifconfig eth0 down && ifconfig eth0 up`

### Setting persistent configuration

* sample ‌`/etc/network/interfaces` configuration

```
network 191.36.8.32
address 191.36.8.36
gateway 191.36.8.62
broadcast 191.36.8.63
netmask 255.255.255.224
dns-nameservers 191.36.8.2
dns-nameservers 191.36.8.3
```

* after changing, restart the interface (e.g. `auto eth0 iface eth0 inet static`)

### scan devices

* using nmap `$ sudo nmap -sn 192.168.0.0/24`

### using ip command

* show all interfaces configuration `$ ip a`
* add an ip to an interface (not persistent) `$ ip a add 192.168.0.1/24 dev eth0`
* Remove an ip from an interface `$ ip a del 192.168.0.1/24 dev eth0`
* deactivate an interface `$ ip link set dev eth0 down`
* activate an interface `$ ip link set dev eth0 up`
* modifying a MAC address of an interface (interface must be deactivated) `$ ip link set dev eth0 address 00:0c:13:45:5b:b6`
* add default route (default may be replaced by 0/0) `$ ip route add default via 192.168.0.254`
* add a static route to a subnetwork `$ ip route add 10.0.0.0/24 via 192.168.0.254 dev eth0`

### useful tools

* ip calculator `# ipcalc 191.36.8.36/27`