Like almost any other aspect of administering a system, running Exchange Instant Messaging requires a certain amount of security consciousness. Exchange IM (EIM) has its own fair share of security issues to be aware of.
One security issue is that Exchange Instant Messaging uses a maximum password length of 16 characters. If users have domain passwords that are longer than 16 characters, they may not be able to log into Exchange Instant Messaging. For that reason, administrators may want to consider setting a global policy that restricts the maximum password length to 16 characters in the domain where Instant Messaging is used.
Another possible problem can arise from being over-conscious of security. If an administrator decides to tighten security by forcing the use of SSL on the Instant Messaging virtual directory for IIS, users who attempt to sign in will be plagued with the authentication error:
Exchange Instant Messaging authentication failure.
The person logged on to this computer does not have permission to use the specified email address. Please supply an email address and logon credentials for that address.
The problem, of course, is that SSL and Exchange Instant Messaging are not intended to work together. Some third-party security auditing tools also might try to tighten security by recommending SSL-only connections on that directory.
This error can also come up if the Instant Messenger virtual server is incorrectly named with the NetBIOS name of the server instead of the fully qualified domain name (FQDN) of the server. To fix this:
- Disable instant messaging for all users. To do this, open Exchange System Manager, select all the users that use Instant Messaging, right-click on that selection, and then select Exchange Tasks -> Disable Instant Messaging.
- Delete the DNS_rvp record for that server.
- Delete the reference to the Instant Messaging server from the Exchange System Manager. This is done by deleting the "Instant Messaging (RVP)" object from the Protocols object.
- Rebuild the Recipient Update Services. To do this, open the Exchange System Manager, double-click the Recipients object, click Recipient Update Services, then right-click on each Recipient Update Service item listed and select Rebuild.
- Run ipconfig /flushdns from the command line to empty the DNS cache.
- Reboot the server and re-enable Instant Messaging for all users. Microsoft says that the proper logon format for each Instant Messaging user should follow the pattern <UserName>@<IMServerName>.<DomainName>.com/org/net.
Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter. Check out his Windows 2000 blog for his latest advice and musings on the world of Windows network administrators – please share your thoughts as well!