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NAT/PORT Selection

I am running 5.2(1) on a 520. It appears that the PIX is sometimes putting traffic onto port 69. My IDS thinks this is possibly TFTP traffic and trips an alarm. Is there a way to force the traffic to the correct port (or at least to a non-standard port). For example, the PIX took traffic coming from port 123 of a PC to port 69 on the outgoing interface of the PIX. Thanks in advance for any suggestions or help.

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Cisco Employee

Re: NAT/PORT Selection

You can't specify the port the PIX will use specifically, unless of course you use a static then the ports are left the same. The PIX PAT's source ports as follows:

- If the source port is TCP/UDP 1-511, then the PIX will PAT the SRC address to one in that range.

- If the source port is TCP/UDP 512-1023, then the PIX will PAT the SRC address to one in that range.

- If the source port is TCP/UDP 1024-65535, then the PIX will PAT the SRC address to one in that range.

You could set up a filter in your IDS to just ignore any port 69 from the PIX's PAT address.

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