>Date: Sun, 28 Feb 1999 19:40:57 -0600
>From: Matt Farwell <[EMAIL PROTECTED]>
>Subject: dhcp
>
>Does anyone know which ports and protocols are used in the DHCP process?
>If it matters we are running microsoft dhcp server. Even a reference to
>a place that I could find this info would be great.
Matt,
There are RFCs describing the DHCP protocol. There's at least rfc2131,
rfc2132 and rfc951. There might be news ones - I don't know.
The DHCP protocol doesn't make for easy reading.
If ipfwadm firewall rules make any sense to you, here are the server rules
based on the RFCs.
Bob
-----------------------------------------------------------------------
# DHCP server (67, 68)
# allow dhcp clients (68) to connect to dhcp server (67)
# Note: DHCP clients are the only externel source of broadcast
# messages we should see, ever.
ipfwadm -I -a accept -P udp -W $INTERNAL_INTERFACE \
-S $DHCP_CLIENTS 68 \
-D $DHCP_SERVER 67
ipfwadm -O -a accept -P udp -W $INTERNAL_INTERFACE \
-S $DHCP_SERVER 67 \
-D $DHCP_CLIENTS 68
ipfwadm -I -a accept -P udp -W $INTERNAL_INTERFACE \
-S $BROADCAST_0 68 \
-D $DHCP_SERVER 67
ipfwadm -O -a accept -P udp -W $INTERNAL_INTERFACE \
-S $DHCP_SERVER 67 \
-D $BROADCAST_1 68
# Getting renumbered
ipfwadm -O -a accept -P udp -W $INTERNAL_INTERFACE \
-S $BROADCAST_0 67 \
-D $BROADCAST_1 68
# REBINDING: Lease time expired. Fall back to INIT.
ipfwadm -I -a accept -P udp -W $INTERNAL_INTERFACE \
-S $BROADCAST_0 68 \
-D $BROADCAST_1 67
# As a result of the above, they're supposed to change their IP address with
# this message, which is addressed to their new address before the dhcp
# client has received the update.
ipfwadm -0 -a accept -P udp -W $INTERNAL_INTERFACE \
-S $DHCP_SERVER 67 \
-D $DHCP_CLIENTS 68
-----------------------------------------------------------------------
........................................................................
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