Configuração na Rede

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DHCP and firewalls

Firewalls usually have to permit DHCP traffic explicitly. Specification of the DHCP client-server protocol describes several cases when packets must have the source address of 0x00000000 or the destination address of 0xffffffff. Anti-spoofing policy rules and tight inclusive firewalls often stop such packets. Multi-homed DHCP servers require special consideration and further complicate configuration.

To allow DHCP, network administrators need to allow several types of packets through the server-side firewall. All DHCP packets travel as UDP datagrams; all client-sent packets have source port 68 and destination port 67; all server-sent packets have source port 67 and destination port 68. For example, a server-side firewall should allow the following types of packets:

* Incoming packets from 0.0.0.0 or dhcp-pool to dhcp-ip
* Incoming packets from any address to 255.255.255.255
* Outgoing packets from dhcp-ip to dhcp-pool or 255.255.255.255

where dhcp-ip represents any address configured on a DHCP server host and dhcp-pool stands for the pool from which a DHCP server assigns addresses to clients