Change the server IP address

allholy1 · Post by **allholy1** » 2006-03-25 20:21

I'm trying to VNC to my computer that is on the school network. They have Cisco Clean Access, which messes with the IP's and doesn't really make them legit. The only way I can see my true IP is by going to a website like www.whatismyip.com.

VNC doesn't pick up the right IP address... is there anyways I can hardcode the IP address in VNC? I can do a VPN, but then I can't access my comp from work because I can't install the VPN client there. (www.hamachi.cc)

I'm using the most recent RC version of UltraVNC and Windows XP professional.

thanks in advance!

yleclerc · Post by **yleclerc** » 2006-03-26 16:23

The IP that is displayed IS the correct IP address for server. The school is using a Cisco router to control Internet access. Every PC/server that is on the school's network all use IP addresses based on a special range (ie: Private IPs.) The only public address is assigned to the Cisco router and then the router will "forward" IP service requests to the configured service (aka port forwading.) www.whatismyip.com will only show the IP address assigned to the Cisco router.

allholy1 · Post by **allholy1** » 2006-03-30 01:50

IP config brings up a 172.xxx.xxx.xxx number, what is my ip brings up a 131.156.xxx.xxx number, and a utitlity here at work brings up the actual IP address here recognized by the outside network. UltraVNC doesn't recognize this.

Anything I can do?

Shaba1 · Post by **Shaba1** » 2006-03-30 15:40

You need to be clearer. What do you mean by "recognize" What part of ultravnc are you trying to put the ip address into? VncViewer or VncServer? Are you trying to connect and control a machine from outside work to a machine on your work network? Are you trying to connect to a machine outside work from a machine inside your work network. When you post questions here and in general on any tech forum you need to be as detailed as possible in order to get the help you need.

From what you HAVE said, as yleclric(sp) noted it seems as though you are behind a nat router. Whatismyip is giving you the public ip address of the router. There is are ways to do what you want. Maybe using opening up a port if you have access to the router. Maybe using NAT2NAT. Maybe using SC. BUT without more details then you have typed in its hard to know what to reccomend or if a solution is even possible.

allholy1 · Post by **allholy1** » 2006-03-30 16:11

I am on a school campus behind a cisco clean access client. no-ip picks up the IP address of 131.156.xxx.xxx while VNC picks up 172.111.xxx.xxx. When trying to connect to the 172 IP, it doesn't work, but when connecting to the 131.156.xxx.xxx in my school network it works. So it is behind a nat firewall... i'll get the repeater and try and get that working before I post anymore.

*edit*

Still doesn't work with the repeater

I know if I connect using my 131.xxx.xxx.xxx ip address, the firewall does port forwarding to my computer. I'm assuming I have access to all my ports.

Thanks guys.

Shaba1 · Post by **Shaba1** » 2006-03-30 17:55

allholy1 wrote:I am on a school campus behind a cisco clean access client. no-ip picks up the IP address of 131.156.spam.spam while VNC picks up 172.111.spam.spam. When trying to connect to the 172 IP, it doesn't work, but when connecting to the 131.156.spam.spam in my school network it works. So it is behind a nat firewall... i'll get the repeater and try and get that working before I post anymore.

*edit*

Still doesn't work with the repeater

I know if I connect using my 131.spam.spam.spam ip address, the firewall does port forwarding to my computer. I'm assuming I have access to all my ports.

Thanks guys.

Nope you do not have to open up ALL your ports. I have a similar situation here. All you have to do is port foward ONE port to the 172.111.xxx.xxx address. That port should be port 5900 if you are using the standard vnc port. I do not use that. Because its a commonly reconized port and script kiddies would scan for it. So I change my vnc server to listen on another port in the 5900-5999 range. I forwared the external addresss and port to that internal address and port. I then connect the vnc viewer to the external address and port. Everything works beautifully and has for me for year even back when I was using AT&T VNC.

The problem you may run into is that you do not have the authority to open up a port on that firewall. I do since I am the sysadmin. But in normal companies and schools that is a VERY tighthly held ability. Since it opens up a door to your network.

One thing you might consider doing AFTER you are able to make a successful VNC connection is enabling the DSM encryption plugin on both the server and the view. BUT put that off until you get a successful connection.