class CEventHandler
{
public:
    CEventHandler() {};
    ~CEventHandler() {};

    virtual    void        OnAccept(PCLIENT_INFO pclient) {};
    virtual    void        OnDisconnect(PCLIENT_INFO pclient) {};
    virtual    int            OnRead(PCLIENT_INFO pclient, uchar* pinbuf, ulong inbufsize, uchar** poutbuf, ulong* poutbufsize) {return -1;};
    virtual    int            OnIdle(PCLIENT_INFO pclient) {return -1;};
    virtual    void        OnSend(PCLIENT_INFO pclient) {};
};

class CRemoteUser : public CEventHandler
{
public:
    CRemoteUser();
    ~CRemoteUser();

    int                        Init(ushort port, CIndexWriterReader *pindexwr, CErrorLog *perrorlog, CWave *pwave, CSettings *psets);
    void                    Done(void);

    virtual    void            OnAccept(PCLIENT_INFO pclient);
    virtual    void            OnDisconnect(PCLIENT_INFO pclient);
    virtual    int                OnRead(PCLIENT_INFO pclient, uchar* pinbuf, ulong inbufsize, uchar** poutbuf, ulong* poutbufsize);
    virtual    int                OnIdle(PCLIENT_INFO pclient);
    virtual    void            OnSend(PCLIENT_INFO pclient);

private:
};

struct base
{
public :

    virtual void virt_method() { printf("base::virt_method()\n"); }
};

struct s1 : public base 
{
public :

    virtual void virt_method() { printf("s1::virt_method()\n"); }
};

struct s2 : private base 
{
public :

    virtual void virt_method() { printf("s2::virt_method()\n"); }
};

struct s3 : public base 
{
private :

    virtual void virt_method() { printf("s3::virt_method()\n"); }
};

//...

base * ptr = NULL;
base b;
s1 s1_;
s2 s2_;
s3 s3_;

ptr = &b;
ptr->virt_method(); // "base::virt_method()"

ptr = &s1_;
s1_.virt_method();  // "s1::virt_method()"
ptr->virt_method(); // "s1::virt_method()"

ptr = &s2_; /* нет доступа к предку */
s2_.virt_method(); // "s2::virt_method()"
ptr->virt_method();

ptr = &s3_;
s3_.virt_method(); /* нет доступа к методу самого класса */
ptr->virt_method(); // "s3::virt_method()"

E>3) Если ты хочешь чтобы у базы никто, кроме выделенных каких-то пользователей не позвал методы, то надо использовать friend классы видимо, хотя, ИМХО, лучше описать задачу поподробнее, а то какая-то нужда подозрительная.

class CServer
{
public:
    CServer();
    ~CServer();

    int                        CreateServer(ushort port, CEventHandler *pevent) {m_pevent = pevent; return 0;};
    void                    DestroyServer(void);
private:
    CEventHandler            *m_pevent;
};

Srv>class CServer
Srv>    int                        CreateServer(ushort port, CEventHandler *pevent) {m_pevent = pevent; return 0;};
Srv>    void                    DestroyServer(void);
Srv>

class CServer
{
public:
    CServer();
    ~CServer();

        class IEventHandler
        {
            virtual void OnAccept(PCLIENT_INFO pclient) = 0;
            virtual void OnDisconnect(PCLIENT_INFO pclient) = 0;
            virtual int OnRead(PCLIENT_INFO pclient, uchar* pinbuf, 
                        ulong inbufsize, uchar** poutbuf, ulong* poutbufsize) = 0;
            virtual int OnIdle(PCLIENT_INFO pclient) = 0;
            virtual void OnSend(PCLIENT_INFO pclient) = 0;
            friend class CServer;
// Дальше всё как у тебя, но
private:
    IEventHandler            *m_pevent;
};

E>class CServer
E>{
E>public:
E>    CServer();
E>    ~CServer();

E>        class IEventHandler
E>        {
E>            virtual void OnAccept(PCLIENT_INFO pclient) = 0;
E>            virtual void OnDisconnect(PCLIENT_INFO pclient) = 0;
E>            virtual int OnRead(PCLIENT_INFO pclient, uchar* pinbuf, 
E>                        ulong inbufsize, uchar** poutbuf, ulong* poutbufsize) = 0;
E>            virtual int OnIdle(PCLIENT_INFO pclient) = 0;
E>            virtual void OnSend(PCLIENT_INFO pclient) = 0;
E>            friend class CServer;
E>// Дальше всё как у тебя, но
E>private:
E>    IEventHandler            *m_pevent;
E>};

E>

class CServer;
class IEventHandler
{
    virtual    void        OnAccept(PCLIENT_INFO pclient) = 0;
    virtual    void        OnDisconnect(PCLIENT_INFO pclient) = 0;
    virtual    int         OnRead(PCLIENT_INFO pclient, uchar* pinbuf, ulong inbufsize, uchar** poutbuf, ulong* poutbufsize) = 0;
    virtual    int         OnIdle(PCLIENT_INFO pclient) = 0;
    virtual    void        OnSend(PCLIENT_INFO pclient) = 0;
    friend class CServer;
};

class CServer
{
public:
    CServer();
    ~CServer();

    int                     CreateServer(ushort port, IEventHandler *pevent) {m_pevent = pevent; return 0;};
    void                    DestroyServer(void);
private:
    IEventHandler           *m_pevent;
};

class CRemoteUser : private IEventHandler
{
public:
    CRemoteUser();
    ~CRemoteUser();

    int                     Init(ushort port, CIndexWriterReader *pindexwr, CErrorLog *perrorlog, CWave *pwave, CSettings *psets);
    void                    Done(void);

private:
    virtual    void            OnAccept(PCLIENT_INFO pclient);
    virtual    void            OnDisconnect(PCLIENT_INFO pclient);
    virtual    int             OnRead(PCLIENT_INFO pclient, uchar* pinbuf, ulong inbufsize, uchar** poutbuf, ulong* poutbufsize);
    virtual    int             OnIdle(PCLIENT_INFO pclient);
    virtual    void            OnSend(PCLIENT_INFO pclient);
};