Dolphin 7.1 includes the ability to store and track your members IP addresses. Basically after they login the system can store their IP address, which you have the option of enabling or disabling.

To enable or disable storing/tracking IP addresses in Dolphin 7.1 go to:
Tools
-IP Blacklist
--Settings

To enable it, check the box "Enable member IP tracking" and save the changes.

To disable it uncheck the box "Enable member IP tracking" and save the changes.





When enabled you can find your members IP address, their member name, and the date they last logged in on:
Tools
-IP Blacklist
--List





If you wanted to block a member's IP address you would first go to:
Tools
-IP Blacklist
--Settings

In the "IP blacklist mode (1 - total block, 2 - login block):" enter a 1 or 2 for the type of restriction/block you want to use.
1 Will block them from accessing your website completely.
2 Will block/prevent them from logging in, but they can still access areas of your website that they don't need to login to see.

In the "IP list type (0 - disabled, 1 - all allowed except listed, 2 - all blocked except list):" you would enter 0, 1, or 2 depending on your preference.
0 Is disabled.
1 Is everyone is allowed to access your website except the IP addresses you specify.
2 Is everyone is blocked from accessing your website except the ones you specify and list.

Note:
*Be careful with this because you can block everyone including yourself.

The most common would be either 0 - disabled (not used), or 1 everyone is allowed except the ones you specify.

To enable this with a login block/restriction to your website for IP addresses you specify you would set it the following:

Enable member IP tracking: checked
IP blacklist mode: 2
IP list type: 1
Save the changes.





Then on:
Tools
-IP Blacklist
--Manage

You would enter the IP addresses of the member you want to block. You get their IP address from the list page, then enter it in the from and to lines. Set the IP Role to deny. Choose a date in the Expiration date box for how long they should be blocked, and you can enter a brief description of why you blocked them. Then, click the "Apply" button to save the changes.

I would enter something like this:
From: 199.12.65.50
to: 199.12.65.50
IP Role: deny
Expiration date 2013-05-30 00:00
Description: spammer





Assuming you set the blacklist mode and list type in the previous step this would block the IP address 199.12.65.50 from logging into your website until May 30th, 2013 at 12:00 AM (Midnight). After that date/time they could log back in again.

Once you have added it you will see it listed on the bottom with the details you entered.





Things to keep in mind:
Blocking by IP address isn't the most reliable solution especially when it comes to spammers. There are a lot of online tools that will allow people to come to your website with a different IP address. If they do this, they could log back in because they would be using a different IP address that isn't blocked.

It may stop some of the less tech savvy members, but if someone is persistent they could easily get around your IP block.

If you had a non-technical Dolphin site and you wanted to block some members by IP address it would likely work well enough.



Additionally:
Lastly you can also change the time duration that they are stored for in:
Settings
-Advanced Settings
--Pruning

Find:
"Delete stored members IPs older than (days):" box.

By default it is set to 90 days.

If you need to change this simply enter your desired amount of days, and save the changes.