-#ifdef vax || pdp11
-#define IN_CLASSA_NET 0x000000ff /* 8 bits of net # */
-#define IN_CLASSA_LNA 0xffffff00
-#define IN_CLASSB 0x00000008
-#define IN_CLASSB_NET 0x0000ffff /* 16 bits of net # */
-#define IN_CLASSB_LNA 0xffff0000
-#define IN_CLASSC 0x0000000c
-#define IN_CLASSC_NET 0x00ffffff /* 24 bits of net # */
-#define IN_CLASSC_LNA 0xff000000
-#endif
+#define IN_CLASSA(i) ((((long)(i))&0x80000000)==0)
+#define IN_CLASSA_NET 0xff000000
+#define IN_CLASSA_NSHIFT 24
+#define IN_CLASSA_HOST 0x00ffffff
+
+#define IN_CLASSB(i) ((((long)(i))&0xc0000000)==0x80000000)
+#define IN_CLASSB_NET 0xffff0000
+#define IN_CLASSB_NSHIFT 16
+#define IN_CLASSB_HOST 0x0000ffff