Could not open connection to host (ubuntu server) on port 23, 5432, 3306

Question

I have recently installed few packages for telnet, mysql and postgreSQL. I can access all these service locally on the ubuntu server but somehow I am not able to access these services from other machines. Below are the active internet connections using:

sudo netstat -tulpn 

tcp   0    0 0.0.0.0:23     0.0.0.0:*    LISTEN      18776/inetd
tcp   0    0 0.0.0.0:3306   0.0.0.0:*    LISTEN      19451/mysqld
tcp   0    0 0.0.0.0:5432   0.0.0.0:*    LISTEN      8453/postgres

I am not able to figure out what I am missing. I am almost sure that I have configured these packages correctly to allow outside world connections.

When I am trying telnet from windows, I got "Could not open connection to the host, on port 23: Connect failed"

I doubt, my router might have blocked these connections but I don't know how to troubleshoot or unblock these connections. Please suggest, Many thanks!

Solution

Your machine has a local IP address, if you want to access it from the internet you have to do a Static Port Mapping or Static Nating.

the best way to do that is from your router if it support static/custom port mapping by do the following

forward 192.168.0.33 port 23 to 23

and then you can access your server from your public IP address.

these are sample images for the router configurations.

also you can know your public IP from google https://www.google.com.eg/search?q=my+ip or from your router.

Comments

[Ahmed Daif]

are you trying to access it from the local network or the internet ??

[kuri]

I am trying to access it from internet

[kuri]

My machine has local network IP address i,e 192.168.0.33

[kuri]

22 DENY Anywhere 2222 ALLOW Anywhere 80 ALLOW Anywhere 25 ALLOW Anywhere 143 ALLOW Anywhere 110 ALLOW Anywhere 993 ALLOW Anywhere 995 ALLOW Anywhere 8080 ALLOW Anywhere 3306 ALLOW Anywhere 23 ALLOW Anywhere

[kuri]

above is the result of sudo ufw status. Sorry for bad formatting but I don't understand how this damn thing works. I tried using two spaces at the end of each line also using linebreaks <br/>

[2707974]

ok, port 23 is for telnet. Is open. If I understand you try to connect to server and server and pc on same lan? If not, and traffic flow is pc -> router -> internet -> router -> server, you must add port forwarding rule to router on server side.

[hmayag]

@2707974 has a point. If you are using a xDSL modem/router, then look in the setup for something like "virtual servers" or "port forwarding" and create a rule for each one of your servers. Also for postgres make sure that the sever is configured to listen for external TCP/IP connections. The default is to listen only to localhost for security reasons. Read here for more information.

[kuri]

Thanks 2707974 and hmayag. Suggestion to add port forwarding rule in router, works :)