5. Network configuration
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## 5. Network configuration

### 5.1. Network Interfaces

Instead of a generic ethX identifier that Linux® uses to identify a network interface, FreeBSD uses the driver name followed by a number as the identifier. The following output from ifconfig(8) shows two Intel® Pro 1000 network interfaces (`em0` and `em1`):

`%` `ifconfig` em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 options=b<RXCSUM,TXCSUM,VLAN_MTU> inet 10.10.10.100 netmask 0xffffff00 broadcast 10.10.10.255 ether 00:50:56:a7:70:b2 media: Ethernet autoselect (1000baseTX <full-duplex>) status: active em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 options=b<RXCSUM,TXCSUM,VLAN_MTU> inet 192.168.10.222 netmask 0xffffff00 broadcast 192.168.10.255 ether 00:50:56:a7:03:2b media: Ethernet autoselect (1000baseTX <full-duplex>) status: active

### 5.2. IP Configuration

An IP address can be assigned to an interface using ifconfig(8). However, to remain persistent across reboots the IP configuration must be included in `/etc/rc.conf`. The following example specifies the hostname, IP address, and default gateway:

hostname="server1.example.com" ifconfig_em0="inet 10.10.10.100 netmask 255.255.255.0" defaultrouter="10.10.10.1"

Use the following to configure an interface for DHCP:

hostname="server1.example.com" ifconfig_em0="DHCP"

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