使用IP地址和用户名访问Magento Admin面板

Hi I have setup a magento store on a server. but currently we dont have a domain name.i have changed the core config data table values (web/unsecure/base_url and web/secure/base_url) like this: http://{server ip address}/~User name

I can view the site front end, but i cannot log into admin panel like this.
http://{server ip address}/~User name/admin

but i cannot log. Some one can please help me on this.

Thanks in advance

You can check your admin path from local.xml open your local.xml file from

app>etc>local.xml

at the end you can see like

<<frontName>if it set is like admin then admin URL of your site like

yoursite.com/admin

try:

http://{server ip address}/~username/index.php/admin