class PacketFilter
{
    public:

        struct FilterException : public GenericException
        {
                FilterException(const char *message);
                FilterException(const std::string &message);
                operator std::string() const;
        };

        virtual void Save() = 0;        // Save current state
        virtual void Restore() = 0;     // Restore previous saved state.

        virtual void Insert(const PermitRule *rule) = 0; // Insert filter rule
        virtual void Insert(const RejectRule *rule) = 0; // Insert filter rule
        virtual void Insert(const PolicyRule *rule) = 0; // Insert policy rule

        virtual void Remove(const PermitRule *rule) = 0; // Remove filter rule
        virtual void Remove(const RejectRule *rule) = 0; // Remove filter rule
        virtual void Remove(const PolicyRule *rule) = 0; // Remove policy rule

        virtual void Flush(Rule::Chain chain) = 0;       // Flush filter chain rules.
        virtual void Commit() = 0;                       // Commit queued filter rules.
};