IP Helper supports the following pre-defined relay protocols:
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DHCP—UDP port number 67/68
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Net-Bios DNS—UDP port number 137
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Net-Bios Datagram—UDP port number 138
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DNS—UDP port number 53
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Time Service—UDP port number 37
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Wake on LAN (WOL)—UPD port number 7
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mDNS—UDP port number 5353; multicast address 224.0.0.251
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Each protocol has the following configurable options:
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Name—The name of the protocol (case sensitive and unique).
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Port 1/2—The unique UDP port number.
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Translate IP—Translation of the source IP while forwarding a packet.
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Timeout—IP Helper cache timeout in seconds at an increment of 10.
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Raw Mode—Unidirectional forwarding that does not create an IP Helper cache.
This is suitable for most of the user-defined protocols that are used for discovery, for example WOL/mDNS. |
The pre-defined and user-defined IP Helper protocols are displayed in the Relay Protocols panel on the Network > IP Helper page.