Cisco 1605...A little History..

[paul123456]

Hi im new to Cisco so Plz bare with me..im just trying to get a little back-round on what is possible and what comes with defualt configurations. Do Cisco routers come shipped with certian ports blocked? like 135-139? also is it possible to block all ports on the router and open certian ones? also is there a limit on how many ports i can port forward to computers? i know that netgear has a limit.

Thanks, PAUL

 

[l1carter]

Paul,

By default when you order a switch / router it comes with a blank configuration. If you order a switch all pc's in the same network will by default have full access to one another because they will be in vlan 1.

Yes it's possible to block all ports and then allow only what you know needs thru, in fact that is the preferred way. You will want to learn how to configure access-lists on Cisco and you should know that by default there is a deny all at the end. So if you done permit it in the ip extended access-list you will block it by default!

As for the port forwarding…
What are you trying to do? I'm not real sure I understand what you are talking about!

 

[paul123456]

Nice, thanks for the explantation...well i will have a email server, ftp server, web server, and a couple game servers behind the router. Im gonna implement NAT with a cable modem. I do have the 1605 with 3 console ports. Hey i noticed on another post that you said to have ethernet1 as a dchp client, I tried ip address dchp but that doesn't work. how do i configure it be configured for a dhcp client? hey thnks again for these responses..this really helps my understanding.

Thanks, PAUL

 

[HKinNYC]

What he is describing is referred to as PAT (Port Address Translation) by Cisco. From Cisco's <NAT Frequently Asked Questions>

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Q. What is PAT, or NAT overloading?
A. PAT, or NAT overloading, is a feature of Cisco IOS NAT and can be used to translate internal (inside local) private addresses to one or more outside (inside global—usually registered) IP addresses. Unique source port numbers on each translation are used to distinguish between the conversations.

With NAT overload, a translation table entry containing full address and source port information is created.
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To answer the question...

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Q. When configuring for PAT (NAT overloading), what is the maximum number of translations that can be made for each inside global IP address?

A. PAT (NAT overloading) divides the available ports per global IP address into three ranges of 0-511, 512-1023, and 1024-65535. PAT (NAT overloading), assigns a unique source port for each User Datagram Protocol (UDP) or Transmission Control Protocol (TCP) sessions. It will attempt to assign the same port value of the original request. However, if the original source port has already been used, it will start scanning from the beginning of the particular port range to find the first available port and assign it to the conversation.
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Basically it's unlimited.

 

[paul123456]

nice....good explanation. I'll start configuring PAT..hehe
or NAT overloading hehe

Thanks, PAUL