cisco 1841 port forwarding

not sure if this is the right terminology in a cisco router but I simply have to forward a port in our router to an internal lan ip.

in a former life I was a network engineer but never worked on cisco routers so im a complete noob to cisco.  the router is already set up and works perfectly fine.  the network guy that set this up is long gone never to be found evidently.

so Im going to give it the old college try myself.  

can I just log into it with the ip just like any other old router that ive programmed?  

i have an app that connects to a piece of software running on a pc inside the network that's on a simple 192...scheme.  just need to forward the public ip to that internal in the cisco.  

not sure how simple that is compared to a regular home based router.  TIA
coonastyAsked:
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Don JohnstonInstructorCommented:
can I just log into it with the ip just like any other old router that ive programmed?  

Yes. You may need to use SSH instead of telnet. I'm assuming that you've got the credentials to log in with?

It's relatively simple.  You'll add a statement like:

ip nat inside source static tcp <inside IP address> 80 <public IP address> 80 extendable

I'm using port 80 in this example so just change "80" to whatever port number you're using.
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coonastyAuthor Commented:
yeah I have user and pass.  

im actually outside of the network today and tried to log in to the router.  I just opened a browser and typed in our public ip.  says no connection and doesn't do anything.

anything special I need to do to get into the router from outside?  the guy that set it up used to get into it from wherever i think.  i can ping it fine btw
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Don JohnstonInstructorCommented:
You can't use a browser unless the router is setup to accept those connections.

You will need to use a terminal program like putty or teraterm.
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coonastyAuthor Commented:
ok just tried putty.  put our public ip address in using the default port of 22 and ssh.  refused connection error.  

do i need to be inside the office for this to work?
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Don JohnstonInstructorCommented:
Can't say for certain without seeing the config. But that would be standard procedure.
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coonastyAuthor Commented:
im at the office and trying to use putty with the internal ip of the cisco.  its not letting me in.  any ideas of how i can get into this thing?
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Don JohnstonInstructorCommented:
Have you tried telnet and SSH? It could be that only one of those protocols is enabled.

Are you getting any response at all?
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coonastyAuthor Commented:
just tried teraterm as well and getting connection refused.  not sure how to get into this router
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coonastyAuthor Commented:
holy heck telnet just worked
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coonastyAuthor Commented:
ok im in yay!!!

so from where im at just type in:


 ip nat inside source static tcp <inside IP address> 80 <public IP address> 80 extendable

and that should create my path into the inside system?
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coonastyAuthor Commented:
is there a command i can use to see what the existing static and the existing dynamic ip range is...need to assign the inside pc a static and want to make sure its free
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Don JohnstonInstructorCommented:
so from where im at just type in:
Can't say since I don't know what prompt you're at. You will need to be in global config mode.
If you're at the Router-name# prompt, type "config t" and press enter. This will put you in config mode.

is there a command i can use to see what the existing static and the existing dynamic ip range is...need to assign the inside pc a static and want to make sure its free
I'm not sure what you're asking.
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coonastyAuthor Commented:
yeah after typing in the password it brings me to the router name prompt.

so config t and then i can type in the ip nat line?

the computer inside the network that i need to connect to needs an internal static assigned to it (192.168.1.?).  i was wondering if maybe the router had some internal statics set to particular computers on the network.  just wanted to make sure i don't assign one already being used.  but the chances are very slim of that anyway.

so after i type the ip nat line in, i can just type in exit and be done?  btw thx so much for your help!!!
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Don JohnstonInstructorCommented:
Well, there's a bit more to it than that. Is there any chance you could post the (sanitized) config?  

Does the prompt you're at end with a ">" or a "#"?

Is the computer you need to access have a manually assigned IP address or does it get it's IP address with DHCP?  If it's DHCP, does it have to use DHCP or can you manually assign an IP address to it.
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coonastyAuthor Commented:
i don't know how to get the config out of this thing.  

i went into the config t and it had a # sign.

i typed in the command you gave me and hit enter.  i manually assigned a static ip in the computer im trying to get to btw.  so its a done deal on the static.  nothing else is using that ip so im good.

its just at the next line in the config t waiting for another command.  can i test it now or is there more i need to type in?  thx
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coonastyAuthor Commented:
well it works!!! i just tried connecting with my phone and its working now!!!

just exited the telnet session.

man can i paypal you for helping?
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Don JohnstonInstructorCommented:
Yes, you can test it now. As long as the command you entered didn't generate an error, then the command is in force.

To exit config mode type "end".

Then enter "copy run start" and hit enter.  Then hit enter again at the save prompt (do not type anything in, just hit "enter").
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Don JohnstonInstructorCommented:
man can i paypal you for helping?
Thanks! Totally unnecessary.

Next time you need some help, you can use the "Hire Me" feature.  Just click on my name and it will take you to my profile page. Then under the avatar there should be a "Hire Me" and "Message" button. Just let me know what you're working on and I may be able to help.
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coonastyAuthor Commented:
well thanks again!!!  im sure ill need an assist again :)
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