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gdanov
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hairpin nat when router is NATed

Wed Jan 26, 2022 12:46 pm

I use ZTE LTE modem for WAN. Unfortunately it's bridge mode is buggy (or MT is buggy) and freezes frequently, so the modem is in router mode and my MT firewall "sees" 192.168.254.x/24 IP as it's external IP.

I need to implement hairpin nat, but on the MT. Rule like this does the job:
pseudocode
chain: dst-nat src-address: <my lan range> dst-address: <my REAL wan IP> action: dst-nat to-addr: <my MT lan IP> ports and so on
Problem is my WAN IP is not fixed and I can't figure out how to have address list containing my up-to-date wan ip. Suggestions how to have hairpin on NATed router?
 
Sob
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Re: hairpin nat when router is NATed  [SOLVED]

Wed Jan 26, 2022 1:43 pm

You need DDNS (you can use built-in IP->Cloud), then add hostname to address list:
/ip firewall address-list
add list=my-wan-ip address=<your DDNS hostname>
Router will automatically resolve it based on TTL. And then in NAT rule use dst-address-list=my-wan-ip.
Come on people, do you really have to quote full posts? It's annoying and in most cases useless.
 
gdanov
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Re: hairpin nat when router is NATed

Wed Jan 26, 2022 2:09 pm

wow, wasn't aware I can put DNS names in address list. re-resolving is based on the DNS record TTL, right?
 
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anav
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Re: hairpin nat when router is NATed

Wed Jan 26, 2022 2:49 pm

Yup!
Happy reading.......
viewtopic.php?t=179343
I'd rather manage rats than software. Follow my advice at your own risk! (Sob & mkx forced me to write that!)
MTUNA Certified, by the Ascerbic Llama!
 
gdanov
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Re: hairpin nat when router is NATed

Wed Jan 26, 2022 2:54 pm

thanks! technically I don't have src-nat problem and don't need hairpin nat :) but anyhow...
 
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anav
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Re: hairpin nat when router is NATed

Wed Jan 26, 2022 4:01 pm

Whatever is working stick with it!!
( Just for sob: Of course if its not configured my way, ........... there can only be one! )
I'd rather manage rats than software. Follow my advice at your own risk! (Sob & mkx forced me to write that!)
MTUNA Certified, by the Ascerbic Llama!

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