accesing a server which is inside a LAN

Posted on 2003-02-26
Medium Priority
Last Modified: 2010-04-01
Hi. I am trying to make a program like PC anywhere (just to learn), so I should create a server and a client program. The problem comes because my client computer is inside a LAN. By an example it will be easier to explain the problem:
My client computer's IP is
My ISP's IP is
So, my client will be running but if I am outside the LAN, how can I reach it?
How do I have to program it to tell it that the client has to connect to through
And to make things more difficult, is there a way to do it if the LAN's IP is not static (ie, using DHCP)?

Just any comments, ideas or links will be appreciated.
Question by:antoniovincenzo2
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LVL 32

Accepted Solution

jhance earned 90 total points
ID: 8028831
You CANNOT reach a private IP from the outside world unless the FIREWALL provides an inbound path with port mapping or you use some sort of VPN.

Talk to the administrator of this firewall which is protecting this host and see if they will permit you this access.  If not, then you cannot do what you propose.

Author Comment

ID: 8030126
Thanks for your comment, jhance, but let me be sure about this:
But, how "PC Anywhere" can do it? Is the server communicating all the time with some third party, and then the client comunicates with that third party as well? Are you saying that if the administrator of the ISP doesn't allow this kind of access, "PC Anywhere" woudn't work?
I am absolutely NOT assuming that your answer is wrong; on the other hand, for what I've been reading, that's the truth. I just want to check all the options.
Thanks again.

Expert Comment

ID: 8030537
I don't speak for the PCAnywhere team, but I do work for Symantec.  :)  jhance is correct.  Your network isn't fully documented here, but I will make some assumptions.  PCAnywhere consists of a client and a server.  It's the same program, but runs in different modes.  If you were using a 10.x.x.x address as the client and you were using NAT, you would be able to connect to the PCA server running on any computer, whether it was on your local network or on the internet.  However, if the PCA server is running on the 10.x address, you would not be able to see it from outside the local network without using port forwarding or VPN or something like that.  In this case, it would not work if the network isn't properly configured.  BTW, PCA is sort of a bad example to use for an analogy.  The technologies involved are incredibly complex.  There are many layers of the windows OS that we have to hook into to get it to work.  Also, one of the best ways to be able to locate a box on the internet that has an IP address than can change because of DHCP is to use a dynamic dns service.  Then, you can always reference the server by name.
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LVL 32

Expert Comment

ID: 8032381
I'm just going by what you've said (and that is not much, by the way...)

From your description, it seems you have:


If PCAnywhere is to work, there MUST BE a path through the firewall on port 5631.  Port 5631 is the default port used by PCA to communicate.

If there is not opening on port 5631, there is no PCAnywhere connection.

You will have the SAME problem.

Author Comment

ID: 8032642
Thanks a lot guys, i will ask the experts team to split the points.

Expert Comment

ID: 8033377

You asked to split points between jhance (45 points) and bkrahmer (30 points).
I have reduced the points on this question from 75 to 40 as indicated by your request at Community Support. Please copy the URL and create a new question in this topic area for the other Experts to whom you wish to award points. The title of the question should read "Points for", followed by the Expert's name. In the question itself, you should paste the link to the original question and perhaps a comment stating that the points are for their help with that question. Once you have created the new questions, you can go back to the original, and accept the comment from the Expert for whom you did not create a new question. The Experts will  comment in your new "Points for" question(s), which you then accept and grade to close.
If you have any questions, please don't hesitate to ask.
Thank you.

** Mindphaser - Community Support Moderator **

Author Comment

ID: 8044767
Sorry, I don't understand what you are saying. I should create two questions (one "Points for jhance" and another one "points for bkrahmer"), and paste a link to this page, and when they post a comment i accept it and give them the points.
But in that case I would need another 75 points.
Is that what you are saying?

Expert Comment

ID: 8046288
No, just one new question. The other points are awarded when you accept one of the expert's comments. I just noticed that I didn't refund points. Will do right away ...
Accept jhance -> 45 p
New question for bkrahmer -> 30p
LVL 32

Expert Comment

ID: 8063400
>> and have been rewarded with a grade of C.


Expert Comment

ID: 8069347

Consider this your last warning.  You cannot and will not flame users.  When you have issues with them contact us, you know how.

That ends this discussion in this thread.  Anymore concerning this will be via the admins, weslennon@experts-exchange.com , myself at computer101@experts-exchange.com , or netminder@experts-exchange.com

Anymore infractions of this nature will result in a review of your account.

E-E Admin
LVL 32

Expert Comment

ID: 8070783
Next you'll be threatening to CUT MY PAY!!!

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