is it ok to use 1 ip for email, outlook web access & surfing?

[fpower]

Is it possible and/or recommended to have one external static ip address and use it for email, outlook web access and internet access for an office of only 15-20 people, with very light useage?

I currently have a cable modem for internet access, and have 10 users who download their email form the isp who is hosting our web site. I wanted to install an exchange server along with outlook web access in house, but I don't know if it is a good idea because it would all be on one ip address...

I think I could do port forwarding of port 25 to the inside ip for exchange and 80 and 443 for outlook to the outlook web access server, this along with people surfing the web...would this be a good idea?

Some one suggested it would be better to purchase a bank of ip addresses, but money is a huge factor, so I was hoping to get away with as little as possible.

Another person suggested using a service such as dyndns to have my mx record point to them, and then they would forward the email to my dynamic ip address... they give you a program to run which checks the ip address of my dynamic ip and sends any changes tothem, so they will always have a current ip to forward the mail to.
This seems a little to risky for me, but any comments would be appreciated.

Also, I wanted to implement vpn access...
Thanks in advance.

 

[dopehead]

Of course you can run your setup with one address, NAT/PAT will work fine with one address, all you need to consider is that creating new servers on the same ports ie. two webservers or two mailservers at the site will not be possible without getting more ips from the isp, and they prolly wont be contiguous.

Jan

Network Systems Engineer
CCNA/CQS/CCSP

 

[fs483]

Becareful because some ISPs don't allow traffic to pass on port 25 (IE they block port 25) when you are using dynamic IPs with Cable/DSL connections. I have a few customers that are currently using DynDNS on their dynamic IP connections in order to log into their systems through Terminal Services. They also have MS Exchange installed but use POP3 connection to retrieve their emails and use the ISP's SMTP services. It works "almost always" except when DynDNS servers aren't able to update your IP. Doesn't happen often but it still does.

Having fixed IPs is the ideal situation. Most of the time we run one IP for the webserver, one for data server and one for mail server. In my area, the cost of having a bank of fixed ips always comes with a faster connection.

A 1.1Mb DSL connection with dynamic IPs runs around 60$/month. We managed to get for my company's connection (with a bit of negotiations) a 3Mb ADSL line with 16 fixed IPs for 220$/month. As you already know, the cost is quite different but it's worth it in our case.

Anthony