You must use the form user@host, or user@IP - mark@*.webmaster.com, *@shell.org, *@127.0.0.1 are all valid where 10.25.12.10 and *.webchat.org wouldn't be valid because they're missing the userid portion of the mask. You can use the * to replace segments of the hostname or IP address and you can also use a ? to replace a single letter or number in a hostmask. Like *@office??.webmaster.com.
/as oper webmaster access add *@*.webmaster.com
The access mask is checked and if it doesn't match then even if you enter in the correct password the user will not be allowed to gain operator status.
This command deletes a specified mask form the Operators access list.
/as oper webmaster access del *@*.webmaster.com
The mask must match exactly to a mask that was placed using the OPER ACCESS ADD command. A wider mask will not delete masks that are contained in that mask.
Lists the access masks that are configured for the Operator.
/as oper webmaster access list