Hi All, we have a software application that we are trying to use for WOL. It says that its forwarding using port 7725. I thought I had all my ducks in row. I configured my access list, tagged the the SVI with the ip directed broadcast, and added ip forward-protocol udp 7725. However when I try my software app I can never get outside of the subnet that the server is connceted to. Both the server and one of my data networks share the same subnet however, I have a handful of other subnets that I need to forward this port. Here is a partial config of "DO-Switch" which has the server and some hosts in VLAN 1 then another switch's config that has serveral other VLANS that need WOL.
ip address 10.1.0.1 255.255.240.0
ip directed-broadcast 101
no ip mroute-cache
description Wireless WAN B Layer3
ip address 192.168.252.2 255.255.255.0
ip directed-broadcast 101
ip pim sparse-dense-mode
router eigrp 100
ip forward-protocol udp 7725
ip route 0.0.0.0 0.0.0.0 192.168.254.1
no ip http server
access-list 101 permit udp host 10.1.0.6 any eq 7725
Thanks for the reply, where should I add the "ip helper-address 10.x.y.255 " command to every SVI with the exception of Vlan 1? Will this interfere with the other "ip helper-address" commands that I have already set up on the SVI for DHCP? If thats the case do I still need my Access-list and "directed broadcast" command?
1.) The ip forward-protocol command alone does nothing. You need the ip helper-address command, too. The helper address command lets the router interface know that it will be receiving a UDP broadcast from a directly connected client and that it should repackage it as either a directed broadcast to a specific destination subnet or a unicast to a specific machine.
By default, the helper address allows 8 different UDP-based applications to get forwarded, excluding WOL. That is why you need the ip forward-protocol command: to add that UDP-based application to the list of forwarded applications.
2.) The ip directed-broadcast command should be applied to the vlan interface that is expected to receive the directed broadcast from the sending/forwarding router. The directed broadcast is a tool sometimes used by hackers to launch a denial of service attack, so routers block directed broadcasts that are destined for directly connected hosts hanging off the interface.
So, you are dealing with broadcasts in 2 directions - the send side, which is why we use the helper address and the forward protocol commands, and the receive side, which is why we use the ip directed broadcast command.
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