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TFTP connection tracking helper, why?

Could anyone please explain me why TFTP doesn’t work with NAT device?

I understood it’s necessary to enable connection tracking helper for TFTP service but don't know why.

Thanks a lot,
Nitass

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0 BarryG over 19 years ago

If it's anything like FTP, the ports used for transfers are completely random and thus require something watching to figure it out.

Barry
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0 BarryG over 19 years ago

If it's anything like FTP, the ports used for transfers are completely random and thus require something watching to figure it out.

Barry
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0 nitass over 19 years ago in reply to BarryG

Thanks for reply. I understood the TFTP doesn’t use 2 separate connections like FTP. If I misunderstood anything, please let me know.

Thanks,
Nitass
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0 BarryG over 19 years ago in reply to nitass

We're both apparently right...

[ QUOTE ]
To establish a TFTP connection, you send a
packet to port 69, and wait for an answer which will *not* come from port
69. Therefore, the helper module will never kick in, and the first packet
will stay in an "UNREPLIED" state.

[/ QUOTE ]
from https://lists.netfilter.org/pipermail/netfilter-devel/2002-January/006419.html

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