Log snmpv3 auth failures (influxdata#8917)

go.mod

@@ -66,7 +66,7 @@ require (
 	github.com/google/go-github/v32 v32.1.0
 	github.com/gopcua/opcua v0.1.13
 	github.com/gorilla/mux v1.7.3
-	github.com/gosnmp/gosnmp v1.30.0
+	github.com/gosnmp/gosnmp v1.31.0
 	github.com/grpc-ecosystem/grpc-gateway v1.16.0 // indirect
 	github.com/hailocab/go-hostpool v0.0.0-20160125115350-e80d13ce29ed // indirect
 	github.com/harlow/kinesis-consumer v0.3.1-0.20181230152818-2f58b136fee0

go.sum

@@ -590,8 +590,8 @@ github.com/gorilla/mux v1.7.3/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2z
 github.com/gorilla/websocket v0.0.0-20170926233335-4201258b820c/go.mod h1:E7qHFY5m1UJ88s3WnNqhKjPHQ0heANvMoAMk2YaljkQ=
 github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
 github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
-github.com/gosnmp/gosnmp v1.30.0 h1:P6uUvPaoZCZh2EXvSUIgsxYZ1vdD/Sonl2BSVCGieG8=
-github.com/gosnmp/gosnmp v1.30.0/go.mod h1:EIp+qkEpXoVsyZxXKy0AmXQx0mCHMMcIhXXvNDMpgF0=
+github.com/gosnmp/gosnmp v1.31.0 h1:l18tqymKfReKBPr3kMK4mMM+n3DHlIpsZbBBSy8nuko=
+github.com/gosnmp/gosnmp v1.31.0/go.mod h1:EIp+qkEpXoVsyZxXKy0AmXQx0mCHMMcIhXXvNDMpgF0=
 github.com/gregjones/httpcache v0.0.0-20180305231024-9cad4c3443a7/go.mod h1:FecbI9+v66THATjSRHfNgh1IVFe/9kFxbXtjV0ctIMA=
 github.com/gregjones/httpcache v0.0.0-20180305231024-9cad4c3443a7/go.mod h1:FecbI9+v66THATjSRHfNgh1IVFe/9kFxbXtjV0ctIMA=
 github.com/grpc-ecosystem/go-grpc-middleware v1.0.1-0.20190118093823-f849b5445de4/go.mod h1:FiyG127CGDf3tlThmgyCl78X/SZQqEOJBCDaAfeWzPs=

plugins/inputs/snmp/snmp.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"bytes"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"log"
 	"math"
@@ -434,7 +435,17 @@ func (t Table) Build(gs snmpConnection, walk bool) (*RTable, error) {
 			// empty string. This results in all the non-table fields sharing the same
 			// index, and being added on the same row.
 			if pkt, err := gs.Get([]string{oid}); err != nil {
-				return nil, fmt.Errorf("performing get on field %s: %w", f.Name, err)
+				if errors.Is(err, gosnmp.ErrUnknownSecurityLevel) {
+					return nil, fmt.Errorf("unknown security level (sec_level)")
+				} else if errors.Is(err, gosnmp.ErrUnknownUsername) {
+					return nil, fmt.Errorf("unknown username (sec_name)")
+				} else if errors.Is(err, gosnmp.ErrWrongDigest) {
+					return nil, fmt.Errorf("wrong digest (auth_protocol, auth_password)")
+				} else if errors.Is(err, gosnmp.ErrDecryption) {
+					return nil, fmt.Errorf("decryption error (priv_protocol, priv_password)")
+				} else {
+					return nil, fmt.Errorf("performing get on field %s: %w", f.Name, err)
+				}
 			} else if pkt != nil && len(pkt.Variables) > 0 && pkt.Variables[0].Type != gosnmp.NoSuchObject && pkt.Variables[0].Type != gosnmp.NoSuchInstance {
 				ent := pkt.Variables[0]
 				fv, err := fieldConvert(f.Conversion, ent.Value)