---
title: inet_arp_init_ifaddr
framework: Kernel
role: symbol
role_heading: Function
platforms: [macOS 10.4+]
path: kernel/1584163-inet_arp_init_ifaddr
---

# inet_arp_init_ifaddr

## Declaration

```occ
void inet_arp_init_ifaddr(ifnet_t interface, ifaddr_t ipaddr);
```

## Parameters

- `interface`: The interface the packet was received on.
- `ipaddr`: The ip interface address.

## Discussion

Discussion This function should be called in two places, when an IP address is added and when the hardware address changes. This function will setup the ifaddr_t for use with the IP ARP functions. This function will also trigger the transmission of a gratuitous ARP packet. When the SIOCSIFADDR ioctl is handled, the data parameter will be an ifaddr_t. If this is an IP address, inet_arp_init_ifaddr should be called. This is usually performed in the protocol attachment's ioctl handler. When the event handler for the protocol attachment receives a KEV_DL_LINK_ADDRESS_CHANGED event, the event handler should call inet_arp_init_ifaddr for each interface ip address. For an example, see bsd/net/ether_inet_pr_module.c in xnu. Search for inet_arp_init_ifaddr.

## See Also

### Address Resolution

- [inet_arp_handle_input](kernel/1584164-inet_arp_handle_input.md)
- [inet_arp_lookup](kernel/1584165-inet_arp_lookup.md)