A blacklist or block list is a basic access control mechanism that
allows everyone access, except for the members of the black list. The opposite
is a whitelist, which denies access to everybody except for members of the
A blacklist is a list or register of entities that, for one reason or
another, are being denied a particular privilege, service, mobility, access or
A whitelist is a list or register of entities that, for one reason or
another, are being provided a particular privilege, service, mobility, access
With blacklisting, any peer is allowed to connect as long as it does
not appear in the list. With whitelisting, no peer is allowed to connect unless
it appears in the list. An operator may choose to implement one or the other.
You can implement either a blacklist or whitelist; both listing techniques
cannot be implemented simultaneously on a security gateway.