Ubuntu – How to set up an Ubuntu server to be (securely) available from the internet

You need to do 2 things:

• configure nameservers (probably in some control panel of the registrar from which you bought the domain) to point the A record to the (static) IP address of your router (i.e. its external address) - I hope by "I changed my IP address to static" you mean that you contacted your ISP and requested a static IP address from them, not that you configured your machine's local IP to be static (though the latter is needed too)

• Secondly, you go to your router's configuration page (see your router instructions, usually it's something like http://10.0.0.1:8080/) and configure Port Forwarding - i.e. you need to tell your router to take all requests which come to its external interface on port 80 and redirect them into internal network to the IP of your server, then take the response and send it back as if it was generated by the router. So for external world the responses will be coming from the external IP of the router. To which IP your DNS records point to. Easy-peasy.

Also, some ISPs, to protect users, block all incoming connections to the client's IPs or only to some common ports. So the access from outside may not work even if everything is configured correctly. You will need to check with your ISP to figure out how to remove port blocking.

There's no need to change anything in your Ubuntu settings, no need to change permissions on /var/www or anything... as such, it may be beneficial for you if this question was migrated to serverdefault.

First of all, the correct command is: ssh user@my.external.ip.address

And the router should be configured to forward the SSH port 22 to your server's local IP address.

For further debugging:

1) Check that port 22 (SSH) is open on your server and on the router (port forwarding).

2) Check that the SSH server is running on your server

3) Use ping, ssh -v while connecting and look at /var/log/auth.log to debug any further connection problems.

1) On your router: follow router specific instructions

On your server: sudo ufw status (unless you use another firewall configuration utility) or sudo iptables -L (general method, but complex output)

To open port 22: sudo ufw allow 22

cf https://help.ubuntu.com/12.04/serverguide/firewall.html

2) Check it is installed: dpkg -l openssh-server

Check it is running: service ssh status or ps aux | grep sshd

3) On the connecting client:

• ping my.external.ip.address
• ssh -v user@my.external.ip.address

On the server:

• sudo less /var/log/auth.log

You can check the router logs as well if necessary.

Here's an online port scanner: https://www.grc.com/x/ne.dll?bh0bkyd2

I think you can use tools like nmap or other as well, but I'm not that familiar with them yet.

Dealing with a changing external IP address:

1) Get a dynDNS or similar account: http://dyn.com/dns/

Lists of dynamic DNS providers:

• http://dnslookup.me/dynamic-dns/
• http://www.dmoz.org/Computers/Internet/Protocols/DNS/DNS_Providers/Dynamic_DNS/

2) Another solution, is to set up a crontab job, which regularly mails you your external IP address or puts in into an online storage service like dropbox.

Here's a script a friend of mine uses:

    #!/bin/bash
    # Bash script to get the external IP address
    MYWANIP=$(curl http://mire.ipadsl.net | sed -nr -e 's|^.*<span class="ip">([0-9.]+)</span>.*$|\1| p')
    echo "My IP address is: $MYWANIP"

    IPold=$(cat /home/USER/Dropbox/test.txt)
    echo "Previous IP Address: $IPold"

    if [[ $IPold != $MYWANIP ]] ;
    then
      echo "New IP"
      rm /home/USER/Dropbox/test.txt
      echo $MYWANIP >> /home/USER/Dropbox/test.txt;
      echo $MYWANIP;
    else
      echo "Same IP";
    fi

    # example crontab entry:
    ## m h  dom mon dow   command
    ## */10 * * * * /home/USER/Dropbox/test_ip.sh

Router port forwarding:

1) First, figure out your router's local IP address by running:

ip route | grep default

It is usually something like 192.168.x.x.

Alternative ways and other OS solutions:

• https://www.cyberciti.biz/faq/how-to-find-gateway-ip-address/
• http://www.howtogeek.com/233952/how-to-find-your-routers-ip-address-on-any-computer-smartphone-or-tablet/
• https://wiki.amahi.org/index.php/Find_Your_Gateway_IP
• https://portforward.com/networking/routers_ip_address.htm

2) Using any computer connected locally to the router, access the IP found previously, i.e. via http://192.168.1.1 for example. This should bring up the router configuration interface.

3) The next steps vary depending on your router. Here is how it is done on a router with OpenWRT for example:

https://newspaint.wordpress.com/2012/08/26/how-to-add-a-port-forward-using-the-web-interface-on-openwrt-10-03-1/