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Pete Finnigan's Oracle Security Weblog

This is the weblog for Pete Finnigan. Pete works in the area of Oracle security and he specialises in auditing Oracle databases for security issues. This weblog is aimed squarely at those interested in the security of their Oracle databases.

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Nice paper on database links

I saw Lewis Cunningham's post to his blog this evening titled "An Expert's Guide to Oracle Technology" and went for a look. This is a good paper that describes the difference between fixed user, connected user and concurrent user database links as well as between public, shared and global database links. It also talks about heterogeneous services and the two possible types of transparent gateways and generic connectivity. The paper then goes on to give some good examples.

This is a good paper and worth a read if you plan to use database links. Database links are of course a security concern as they are the route in and out of a database when itís connected to another database. If a hacker wants to access a particular database but cannot he may find a way in via another database that has links to the one he would like to access. The biggest issue of database links until recently has been the fact that fixed links keep the password used in the dictionary is SYS.LINK$ in clear text. A better option in terms of not storing a password to another database in clear text is to use concurrent or connected user links. For me the biggest risk is the fact that links offer a way in and out of a database. Be careful with allocating privileges to allow users to create links and also review what links exist in your databases.