variable_list type的值（10进制）： ASN_INTEGER is 2 ASN_OCTET_STR is 4 ASN_BIT_STR is 3 ASN_BIT_STR is 3 ASN_OPAQUE is 68 ASN_OBJECT_ID is 6 ASN_TIMETICKS is 67 ASN_GAUGE is 66 ASN_COUNTER is 65 ASN_IPADDRESS is 64 ASN_NULL is 5 ASN_UINTEGER is 71 ASN_COUNTER64 is 70
