Open web address via button

I don't know that you can do that due to loss of focus that will occur with the modem username and password dialogue box. IE has disabled the old http://admin:password@192.168.1.1 due to security reason and there is a registry hack for this but I am not going to post it as it is against our policy to circumvent security measures of any sort within this forum. If you have a web page that requires a username and password as part of the page rather than a dialogue box you could adapt the following code which is just an example of how to log into gmail automatically. So that fact that we are talking about security issues the rest of your question does become redundant. You can easily create drop down box that is a list of web addresses that contain username/password text entry fields - you just create a table with the web address, username and then password. The drop down list is then just the web address and do a simple vlookup to return the username and password - then you could use the following code to automatically log into the web page. As for pop up dialogues as some banks use for usernames and passwords it is against forum rules to give advice on a security workaround. To follow is how to log into your gmail account using code

Please Login or Register  to view this content.

That is as much help as I can give you as I am not going to break forum rules. If you want to know how to create drop down lists and do vlookups to return values then start another thread posting your requirements and upload a sample workbook showing how you want your workbook set up giving specific examples. Make sure there is no sensitive/private data in the workbook. As for security workarounds no one here is going to help you.
Please read out Forum Rules

11. Don't post questions regarding breaking or bypassing any security measure. Such posts will be deleted, and repeat offenders will be banned. This includes posting of links to sites that offer software, code or services to do this or posting of code to remove passwords.

Can you upload a sample workbook with no sensitive data showing how the data currently is presented and/or how you want it to appear - So in a sample sheet give a few examples of how you want the data to be appear showing the drop down box and what is to be returned. It makes it much easier to supply you an accurate answer if we can see how your workbook is to be constructed and if we can see an example of how the workbook is to appear after the macro/vlookups have returned/processed the data. Select Go Advanced, Manage Attachments and select the dummy workbook to upload. Make sure no sensitive/private data is in the workbook you upload. Do not upload screen dumps as no one wants to reconstruct a workbook based on an image.
You will have a much better chance of getting an answer if you could supply a sample workbook.
What do you want to lookup - a web address/a name of a website? Could you be a little more specific with a sample workbook - saying where you want the drop down box, what is to be returned from the lookup and then once that data is returned I assume you want a button to follow the url that is in A1 - a sample workbook showing how you want your data presented will enable me or someone else to give you a better answer

Attach the following code to a button

Please Login or Register  to view this content.

I have attached the workbook with the code - I changed the first IP address as this is my router IP local address for testing - it works fine for me? Try the attachment - it will open IE and place the local address into the IE address bar with the port number specified - report back if you have problems