Unable to contact the remote controller

[Stefanos Ntouvlis]

Greetings,
i am trying to do some work with mininet-wifi and pox controller having as reference Brian's tutorial (https://www.brianlinkletter.com/2015/09/using-pox-components-to-create-a-software-defined-networking-application/#fn1-3488) and this video(https://www.youtube.com/watch?v=neT8yyuGqVc&list=PLc-DtsgeIdzENYnpFKlWQ_u3X1FBg3YHK&index=18&t=271s) but the issue i am facing is that when i start the simulation before i start the pox controller this is printed on my terminal

alekos@alekos-X555LB:~$ sudo mn --wifi  --topo linear,5  --controller=remote,ip=127.0.0.1,port=6633
*** Adding stations:
sta1 sta2 sta3 sta4 sta5
*** Adding access points:
ap1 ap2 ap3 ap4 ap5
*** Configuring wifi nodes...
*** Creating network
*** Adding controller
Unable to contact the remote controller at 127.0.0.1:6633
*** Adding hosts:

*** Adding switches:

*** Adding links:
(ap2, ap1) (ap3, ap2) (ap4, ap3) (ap5, ap4) (sta1, ap1) (sta2, ap2) (sta3, ap3) (sta4, ap4) (sta5, ap5)
*** Starting controller(s)
c0
*** Starting L2 nodes
ap1 ap2 ap3 ap4 ap5 ...
*** Starting CLI:

I have tried setting the controller ip also via miniedit to my ethernet ip and it prints the same message, whereas  when i start the pox controller first and the i put my ip everything runs fine.
Could you give me a hint about why is this happening?

By the way, so as not to bother you again after that. After i set the ip e.g 192.168.xx.xx where should i look in wireshark to see the transmitted messages, because i am a bit confused as to if i should check loopback or some other interface.
Thanks in advance.

Regards,
Stefanos Ntouvlis

[Ramon Fontes]

What is the outcome for "telnet 127.0.0.1 6633"?

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[Stefanos Ntouvlis]

alekos@alekos-X555LB:~$ telnet 127.0.0.1 6633
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused

[Ramon Fontes]

> Trying 127.0.0.1...
> telnet: Unable to connect to remote host: Connection refused

As you can see, the controller is not running (working?) on port 6633.

[Stefanos Ntouvlis]

Isn't that made possible by customizing the controller's port on mininet or via command line typing, port=6633?

[Ramon Fontes]

Dear,

Did you mean customize or connect to the port where the controller is running on? Are you using a remote controller, right??

[Stefanos Ntouvlis]

I am really sorry if my questions seem stupid, i am not too familiar with networking of this level and i am trying hard to do my dissertation.
It is just that in Brian's tutorial he mentions this:
"We defined the remote controller address and TCP port as 127.0.0.1:6633 because we know from POX documentation it will be listening on port 6633." (Maybe it is outdated?)
Of course this is for plain mininet, not mn-wifi, but the outcome is the same.

[Ramon Fontes]

This is not really about networking. This is about basic OS concepts - an application cannot connect to a service if it is not available for use.

[Stefanos Ntouvlis]

I understand my main issue is that i do not understand why it is not available and how to make it, in such a case.
Anyway i don't want to bother you any longer if i have something specific i will ask you in another thread.
Thanks