I was looking some examples on how to connect mysql/tomcat from a remote system. (ex1, ex2, ex3)

I have just provided some links though there are many available. In all the examples I have seen nobody is disclosing his external IP. Some write 'x.x.x.x', some write 'externalIP' and some use other ways. I am just curious to know why people do not disclose their external IP, but do they show their local IP like Can people hack into a system by knowing the external IP or are there any other reasons?

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    It's same as writing your Home address in public place without your name. – codeSetter Feb 6 '14 at 13:09

Giving your real IP address is not really recommended but it's not usually harmful (after all, every time you go to a website, its owner can see your address, and thankfully most of them have better things to do than attacking you).

Now, posting it in a message where you also explain you just turned off both your firewall and your antivirus will really get some attention from the bad persons.

Regarding the fact that you even consider turning those off, I would say the right answer for you is do not post your IP address anywhere!

Now, about your comments to previous answers: you don't have to turn off your firewall to allow connection to one server running on your pc. Just configure it to open the port you need.

Also I'm kind of sure disabling your antivirus will not help at all. Don't do that.

If as I assume you have issues to connect to a server running on your pc from outside your local network, the source of the problem is usually one of those two:

  • you have a router, and you need to configure port forwarding on your router (not on your pc)
  • your server software is configure to only accept local connections (connections originating from the same pc it is running on), and you need to change this setting (Google this since it depends of the actual server you're trying to configure)

Good luck!

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  • Thanks for the answer,+1.I have done the port forwarding but still I am not able to access from internet.I saw some questions in some forums and they said to turn off windows firewall and so i turned it off – SpringLearner Feb 6 '14 at 7:49
  • @JqueryLearner your next move is to check that your server software is listening on the actual network card, and not only on the loopback device. You will have to look on your server documentation for this. Also while you're into the documentation find how to activate debug log. That may give you some useful information if it still doesn't work – LeFauve Feb 6 '14 at 8:09
  • Having just read your comment in another answer about your server accepting connexions from local network, my previous comment won't help (if you can actually connect from another computer, your server is already listening on the actual network card). You may instead check your port forwarding again. – LeFauve Feb 6 '14 at 8:38
  • See tomcat server is installed in so to access from another system I just type but for accessing from internet when I type externalIP:8080/aap then its working.I have done the port forwarding – SpringLearner Feb 6 '14 at 9:06
  • Ok... So if it work from both your local network and an external computer, what is your issue again? – LeFauve Feb 7 '14 at 6:16

There is a potential that if you post your public IP that you will draw more attention to it, then what it would normally receive by simply being on the Internet. Ideally your firewall and host security should already be strong enough to withstand and attacks. There is nothing inherently secret about an IP address. They have to be known for communication to happen.

There is a network reserved explicitly for documentation and sharing So feel free to use that, or one of the other RFC 5735 ranges that are reserved for internal networks or documentation.

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  • My problem was connecting to mysql and tomcat from a remote system. And I wanted to post the codes for it.So If i have my windows firewall turned off and antivirus also turned off then will it create problem If i include externalIp in my codes – SpringLearner Feb 6 '14 at 6:57
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    @JqueryLearner Put it this way, would you give a stranger your home address (your external publicly accessible IP address), leave your door wide open (Firewall set to off), and put the guard dog into the kennel (turn off anti virus)? Mind you, having anti virus alone may not help as anti virus often can't detect new viruses until they found a sample, and create detection method for the virus. – Darius Feb 6 '14 at 7:13
  • @Darius Thanks for your comment.I have done an app using jsp and its hosted in my local system so users within my LAN can only access it.I read some where that using port forwarding any one in the world can access my app and so I have done port forwarding also but still I am not able to access from internet.So I thought of posting question reagrding the problem.So before posting the question I wanted to know is it bad to post externalIP or not.Hope you understood why I turned off windows firewall.If you know how to make local app to be available to internet then please share your knowledge – SpringLearner Feb 6 '14 at 7:54
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    Check out pagekite.net, they offer a proxy service that allows you to expose a local web server on a public address. Free trial, and it's free software, so you could put the public end on a VPS or on a friend's server that has a public IP. – clacke Feb 6 '14 at 10:04
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    @JqueryLearner: Do not turn off your firewall and antivirus. – Marcks Thomas Feb 6 '14 at 12:46

yes and no, the Problem is not hacking (there for they have a firewall which should not let Bad-Things happen) but you can do so called DDOS Attack against the Server/Firewall over the public IP.

Also its not usefull if you write your public IP (cause many DAU users just copy past code, and then you have a problem cause their System would have the same ip as yours which is really bad cause a public ip must be unique.

internal ip is no problem they can just use the same cause its behind the router (the problem with not beeing unique is stuck on their own network so no problem for you)

i hope this helps. sry my bad english - was in a hurry and my motherlanguage is german not english.

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  • Thanks for answering,+1.So do you think If I provide externalIP to users and turn off windows firewall off and antivirus also will create problem – SpringLearner Feb 6 '14 at 6:54

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