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Archer A9 and 21 port forwarding

Archer A9 and 21 port forwarding

Archer A9 and 21 port forwarding
Archer A9 and 21 port forwarding
Thursday - last edited Thursday
Tags: #Port Forwarding
Model: Archer A9  
Hardware Version: V6
Firmware Version: 1.0.4 Build 20190522 rel.66382(5255)

Hello, tried to add port forwarding for 21 port. made needed settings like 21 -> 2021 port. 

 

in result it works in strange way:

 

1. run telnet-command using terminal/filezilla OUTSIDE router local network - SUCCESS

telnet x.x.x.x 21

Trying x.x.x.x...
Connected to x.x.x.x
Escape character is '^]'.
220 ProFTPD Server (Debian) [x.x.x.x]

 

2. run telnet-command using terminal/filezilla INSIDE router local network - FAIL

telnet x.x.x.x 21
Trying x.x.x.x...
telnet: connect to address x.x.x.x: Operation timed out
telnet: Unable to connect to remote host

 

also tried to disable FTP ALG, TFTP ALG - no changes.

 

if i change port forwarding to 211 -> 2021 - then BOTH cases work SUCCESSFULLY.

 

question:

what is the reason and suggested ways to achieve my basic case with port 21?

 

thanks!

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#1
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Re:Archer A9 and 21 port forwarding
Saturday - last edited Saturday

  @lon9man 

 

According to your port-forwarding rule, the correct test from inside your local network should be:

telnet 192.168.1.104 2101
If x.x.x.x is your external public IP address, this probably is some issue of router hairpinning / NAT loopback with port 21.

Another culprit could be the Debian utilities, like nftables or iptables, if you're using these.

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#2
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Re:Archer A9 and 21 port forwarding
Saturday

  @terziyski thanks for the response!


2101 port works as expected.

 

> If x.x.x.x is your external public IP address, this probably is some issue of router hairpinning / NAT loopback with port 21.

yes, x.x.x.x - it is my public DNS name, which routes to public IP.

My basic tests (described in first post) were by using terminal on Mac and remote AWS EC2-instance.
Next I tested same cases using separate iPad (tried to connect using ftp client app) on:

a) same WiFi-network - FAILED

b) mobile LTE-network - SUCCESS

 

so results are the same. So it seems router has some internal logic related to 21 port, which is not described clearly by the producer.


> Another culprit could be the Debian utilities, like nftables or  iptables, if you're using these.

I don't use any custom settings 

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#3
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Re:Archer A9 and 21 port forwarding
Saturday

  @lon9man 

 

Usually people change (for security reasons) the default FTP port 21 to something else like you did to 2101, but from the outside.

On the inside you can use the standard port 21. In this case your router rule would look like this:

In this case, probably you won't have this issue.

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Re:Archer A9 and 21 port forwarding
Saturday - last edited Saturday

  @terziyski 

 

> Usually people change (for security reasons) the default FTP port 21 to something else like you did to 2101, but from the outside.

 I can understand everything)) people can, but producer should give clear options for own product. It is not something complex like space mission.. it is port forwarding.

 

And I have paid for the device, which should do concrete things, which I am trying to achieve OR in opposite it should have docs with clear descriptions how it works with such nuances like "21 port".


i understand that I can use any other port and it will work, BUT:

3rd party service, which I use strictly needs 21 port to use for FTP connection without any possibility to change to the other port. So my case needs concrete this numbers.

 

Maybe you know: any producer's related member answers here on this forum or not?

 

thanks!

 

P.S. 2101 port on local side needs to contact with docker con

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#5
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Re:Archer A9 and 21 port forwarding
Yesterday - last edited Yesterday

  @lon9man 

 

I see that you're using a rather old FW release (details). What I would do is to update the A9 FW to the latest FW release available.

This issue may have been resolved in newer FW releases. You can download Archer A9(EU)_V6_210315 from here and test if there's any improvement.

If you're not comfortable doing that or there's no improvement, you can always contact your local support for further assistance.

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Re:Archer A9 and 21 port forwarding
Yesterday - last edited Yesterday

  @terziyski 

upgraded to 1.1.1 Build 20210315 rel.40637(5255).

 

nothing changed. behavior is completely the same.

 

wrote email here: https://www.tp-link.com/uk-ua/support/contact-technical-support/#E-mail-Support

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