-
Notifications
You must be signed in to change notification settings - Fork 4.9k
/
convert.go
482 lines (428 loc) · 12.9 KB
/
convert.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
// or more contributor license agreements. Licensed under the Elastic License;
// you may not use this file except in compliance with the Elastic License.
package netflow
import (
"encoding/base64"
"encoding/binary"
"net"
"strconv"
"strings"
"time"
"github.com/cespare/xxhash/v2"
"github.com/elastic/beats/v7/libbeat/beat"
"github.com/elastic/beats/v7/libbeat/common"
"github.com/elastic/beats/v7/libbeat/common/flowhash"
"github.com/elastic/beats/v7/x-pack/filebeat/input/netflow/decoder/record"
)
var (
// RFC 1918
privateIPv4 = []net.IPNet{
{IP: net.IPv4(10, 0, 0, 0), Mask: net.IPv4Mask(255, 0, 0, 0)},
{IP: net.IPv4(172, 16, 0, 0), Mask: net.IPv4Mask(255, 240, 0, 0)},
{IP: net.IPv4(192, 168, 0, 0), Mask: net.IPv4Mask(255, 255, 0, 0)},
}
// RFC 4193
privateIPv6 = net.IPNet{
IP: net.IP{0xfd, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
Mask: net.IPMask{0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
}
)
func toBeatEvent(flow record.Record) (event beat.Event) {
switch flow.Type {
case record.Flow:
return flowToBeatEvent(flow)
case record.Options:
return optionsToBeatEvent(flow)
default:
return toBeatEventCommon(flow)
}
}
func toBeatEventCommon(flow record.Record) (event beat.Event) {
// replace net.HardwareAddress with its String() representation
fixMacAddresses(flow.Fields)
// Nest Exporter into netflow fields
flow.Fields["exporter"] = fieldNameConverter.ToSnakeCase(flow.Exporter)
// Nest Type into netflow fields
switch flow.Type {
case record.Flow:
flow.Fields["type"] = "netflow_flow"
case record.Options:
flow.Fields["type"] = "netflow_options"
default:
flow.Fields["type"] = "netflow_unknown"
}
// ECS Fields -- event
ecsEvent := common.MapStr{
"created": flow.Timestamp,
"kind": "event",
"category": "network_traffic",
"action": flow.Fields["type"],
}
// ECS Fields -- device
ecsDevice := common.MapStr{}
if exporter, ok := getKeyString(flow.Exporter, "address"); ok {
ecsDevice["ip"] = extractIPFromIPPort(exporter)
}
event.Timestamp = flow.Timestamp
event.Fields = common.MapStr{
"netflow": fieldNameConverter.ToSnakeCase(flow.Fields),
"event": ecsEvent,
"observer": ecsDevice,
}
return
}
func extractIPFromIPPort(address string) string {
// address can be "n.n.n.n:port" or "[hhhh:hhhh::hhhh]:port"
if lastColon := strings.LastIndexByte(address, ':'); lastColon > -1 {
address = address[:lastColon]
}
if len(address) > 0 && address[0] == '[' {
address = address[1:]
}
if n := len(address); n > 0 && address[n-1] == ']' {
address = address[:n-1]
}
return address
}
func optionsToBeatEvent(flow record.Record) beat.Event {
for _, key := range []string{"options", "scope"} {
if iface, found := flow.Fields[key]; found {
if opts, ok := iface.(record.Map); ok {
fixMacAddresses(opts)
flow.Fields[key] = fieldNameConverter.ToSnakeCase(opts)
}
}
}
return toBeatEventCommon(flow)
}
func flowToBeatEvent(flow record.Record) (event beat.Event) {
event = toBeatEventCommon(flow)
ecsEvent, ok := event.Fields["event"].(common.MapStr)
if !ok {
ecsEvent = common.MapStr{}
event.Fields["event"] = ecsEvent
}
sysUptime, hasSysUptime := getKeyUint64(flow.Exporter, "uptimeMillis")
if !hasSysUptime || sysUptime == 0 {
// Alternative update
sysUptime, hasSysUptime = getKeyUint64(flow.Fields, "systemInitTimeMilliseconds")
}
startUptime, hasStartUptime := getKeyUint64(flow.Fields, "flowStartSysUpTime")
endUptime, hasEndUptime := getKeyUint64(flow.Fields, "flowEndSysUpTime")
if hasSysUptime {
// Can't convert uptime values to absolute time if sysUptime is bogus
// It will result on a flow that starts and ends in the future.
hasStartUptime = hasStartUptime && startUptime <= sysUptime
hasEndUptime = hasEndUptime && endUptime <= sysUptime
if hasStartUptime {
ecsEvent["start"] = flow.Timestamp.Add((time.Duration(startUptime) - time.Duration(sysUptime)) * time.Millisecond)
}
if hasEndUptime {
ecsEvent["end"] = flow.Timestamp.Add((time.Duration(endUptime) - time.Duration(sysUptime)) * time.Millisecond)
}
if hasStartUptime && hasEndUptime {
ecsEvent["duration"] = ecsEvent["end"].(time.Time).Sub(ecsEvent["start"].(time.Time)).Nanoseconds()
}
}
if ecsEvent["duration"] == nil {
if durationMillis, found := getKeyUint64(flow.Fields, "flowDurationMilliseconds"); found {
duration := time.Duration(durationMillis) * time.Millisecond
ecsEvent["duration"] = duration
// Here we're missing at least one of (start, end)
if start := ecsEvent["start"]; start != nil {
ecsEvent["end"] = start.(time.Time).Add(duration)
} else if end := ecsEvent["end"]; end != nil {
ecsEvent["start"] = end.(time.Time).Add(-duration)
}
}
}
flowDirection, hasFlowDirection := getKeyUint64(flow.Fields, "flowDirection")
// ECS Fields -- source and destination
ecsSource := common.MapStr{}
ecsDest := common.MapStr{}
// Populate first with WLAN fields
if hasFlowDirection {
staIP, _ := getKeyIP(flow.Fields, "staIPv4Address")
staMac, hasStaMac := getKeyString(flow.Fields, "staMacAddress")
wtpMac, hasWtpMac := getKeyString(flow.Fields, "wtpMacAddress")
if hasStaMac && hasWtpMac {
srcMac := staMac
srcIP := staIP
dstMac := wtpMac
var dstIP net.IP = nil
if Direction(flowDirection) == DirectionOutbound {
srcMac, dstMac = dstMac, srcMac
srcIP, dstIP = dstIP, srcIP
}
if srcIP != nil {
ecsSource["ip"] = srcIP
ecsSource["locality"] = getIPLocality(srcIP).String()
}
ecsSource["mac"] = srcMac
if dstIP != nil {
ecsDest["ip"] = dstIP
ecsDest["locality"] = getIPLocality(dstIP).String()
}
ecsDest["mac"] = dstMac
}
}
// Regular IPv4 fields
if ip, found := getKeyIP(flow.Fields, "sourceIPv4Address"); found {
ecsSource["ip"] = ip
ecsSource["locality"] = getIPLocality(ip).String()
}
if sourcePort, found := getKeyUint64(flow.Fields, "sourceTransportPort"); found {
ecsSource["port"] = sourcePort
}
if mac, found := getKeyString(flow.Fields, "sourceMacAddress"); found {
ecsSource["mac"] = mac
}
// ECS Fields -- destination
if ip, found := getKeyIP(flow.Fields, "destinationIPv4Address"); found {
ecsDest["ip"] = ip
ecsDest["locality"] = getIPLocality(ip).String()
}
if destPort, found := getKeyUint64(flow.Fields, "destinationTransportPort"); found {
ecsDest["port"] = destPort
}
if mac, found := getKeyString(flow.Fields, "destinationMacAddress"); found {
ecsDest["mac"] = mac
}
// ECS Fields -- Flow
ecsFlow := common.MapStr{}
var srcIP, dstIP net.IP
var srcPort, dstPort uint16
var protocol IPProtocol
if ip, found := getKeyIP(record.Map(ecsSource), "ip"); found {
srcIP = ip
}
if ip, found := getKeyIP(record.Map(ecsDest), "ip"); found {
dstIP = ip
}
if port, found := getKeyUint64(flow.Fields, "sourceTransportPort"); found {
srcPort = uint16(port)
}
if port, found := getKeyUint64(flow.Fields, "destinationTransportPort"); found {
dstPort = uint16(port)
}
if proto, found := getKeyUint64(flow.Fields, "protocolIdentifier"); found {
protocol = IPProtocol(proto)
}
if srcIP == nil {
srcIP = net.IPv4(0, 0, 0, 0).To4()
}
if dstIP == nil {
dstIP = net.IPv4(0, 0, 0, 0).To4()
}
ecsFlow["id"] = flowID(srcIP, dstIP, srcPort, dstPort, uint8(protocol))
ecsFlow["locality"] = getIPLocality(srcIP, dstIP).String()
// ECS Fields -- network
ecsNetwork := common.MapStr{}
if proto, found := getKeyUint64(flow.Fields, "protocolIdentifier"); found {
ecsNetwork["transport"] = IPProtocol(proto).String()
ecsNetwork["iana_number"] = proto
}
countBytes, hasBytes := getKeyUint64Alternatives(flow.Fields, "octetDeltaCount", "octetTotalCount", "initiatorOctets")
countPkts, hasPkts := getKeyUint64Alternatives(flow.Fields, "packetDeltaCount", "packetTotalCount", "initiatorPackets")
revBytes, hasRevBytes := getKeyUint64Alternatives(flow.Fields, "reverseOctetDeltaCount", "reverseOctetTotalCount", "responderOctets")
revPkts, hasRevPkts := getKeyUint64Alternatives(flow.Fields, "reversePacketDeltaCount", "reversePacketTotalCount", "responderPackets")
if hasRevBytes {
ecsDest["bytes"] = revBytes
}
if hasRevPkts {
ecsDest["packets"] = revPkts
}
if hasBytes {
ecsSource["bytes"] = countBytes
if hasRevBytes {
countBytes += revBytes
}
ecsNetwork["bytes"] = countBytes
}
if hasPkts {
ecsSource["packets"] = countPkts
if hasRevPkts {
countPkts += revPkts
}
ecsNetwork["packets"] = countPkts
}
if biflowDir, isBiflow := getKeyUint64(flow.Fields, "biflowDirection"); isBiflow && len(ecsSource) > 0 && len(ecsDest) > 0 {
// swap source and destination if biflowDirection is reverseInitiator
if biflowDir == 2 {
ecsDest, ecsSource = ecsSource, ecsDest
}
ecsEvent["category"] = "network_session"
// Assume source is the client in biflows.
event.Fields["client"] = ecsSource
event.Fields["server"] = ecsDest
}
ecsNetwork["direction"] = "unknown"
if hasFlowDirection {
ecsNetwork["direction"] = Direction(flowDirection).String()
}
if ssid, found := getKeyString(flow.Fields, "wlanSSID"); found {
ecsNetwork["name"] = ssid
}
ecsNetwork["community_id"] = flowhash.CommunityID.Hash(flowhash.Flow{
SourceIP: srcIP,
SourcePort: srcPort,
DestinationIP: dstIP,
DestinationPort: dstPort,
Protocol: uint8(protocol),
})
if len(ecsFlow) > 0 {
event.Fields["flow"] = ecsFlow
}
if len(ecsSource) > 0 {
event.Fields["source"] = ecsSource
}
if len(ecsDest) > 0 {
event.Fields["destination"] = ecsDest
}
if len(ecsNetwork) > 0 {
event.Fields["network"] = ecsNetwork
}
return
}
func getKeyUint64(dict record.Map, key string) (value uint64, found bool) {
iface, found := dict[key]
if !found {
return
}
value, found = iface.(uint64)
return
}
func getKeyUint64Alternatives(dict record.Map, keys ...string) (value uint64, found bool) {
var iface interface{}
for _, key := range keys {
if iface, found = dict[key]; found {
if value, found = iface.(uint64); found {
return
}
}
}
return
}
func getKeyString(dict record.Map, key string) (value string, found bool) {
iface, found := dict[key]
if !found {
return
}
value, found = iface.(string)
return
}
func getKeyIP(dict record.Map, key string) (value net.IP, found bool) {
iface, found := dict[key]
if !found {
return
}
value, found = iface.(net.IP)
return
}
// Replaces each net.HardwareAddr in the dictionary with its string representation
// because HardwareAddr doesn't implement Marshaler interface.
func fixMacAddresses(dict map[string]interface{}) {
for key, value := range dict {
if asMac, ok := value.(net.HardwareAddr); ok {
dict[key] = asMac.String()
}
}
}
type Locality uint8
const (
LocalityPrivate Locality = iota + 1
LocalityPublic
)
var localityNames = map[Locality]string{
LocalityPrivate: "private",
LocalityPublic: "public",
}
func (l Locality) String() string {
name, found := localityNames[l]
if found {
return name
}
return "unknown (" + strconv.Itoa(int(l)) + ")"
}
func isPrivateNetwork(ip net.IP) bool {
for _, net := range privateIPv4 {
if net.Contains(ip) {
return true
}
}
return privateIPv6.Contains(ip)
}
func isLocalOrPrivate(ip net.IP) bool {
return isPrivateNetwork(ip) ||
ip.IsLoopback() ||
ip.IsUnspecified() ||
ip.Equal(net.IPv4bcast) ||
ip.IsLinkLocalUnicast() ||
ip.IsLinkLocalMulticast() ||
ip.IsInterfaceLocalMulticast()
}
func getIPLocality(ip ...net.IP) Locality {
for _, addr := range ip {
if !isLocalOrPrivate(addr) {
return LocalityPublic
}
}
return LocalityPrivate
}
// TODO: create table from https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml
// They have a CSV file available for conversion.
type IPProtocol uint8
const (
ICMP IPProtocol = 1
TCP IPProtocol = 6
UDP IPProtocol = 17
IPv6ICMP IPProtocol = 58
)
var ipProtocolNames = map[IPProtocol]string{
ICMP: "icmp",
TCP: "tcp",
UDP: "udp",
IPv6ICMP: "ipv6-icmp",
}
func (p IPProtocol) String() string {
name, found := ipProtocolNames[p]
if found {
return name
}
return "unknown (" + strconv.Itoa(int(p)) + ")"
}
func flowID(srcIP, dstIP net.IP, srcPort, dstPort uint16, proto uint8) string {
h := xxhash.New()
// Both flows will have the same ID.
if srcPort >= dstPort {
h.Write(srcIP)
binary.Write(h, binary.BigEndian, srcPort)
h.Write(dstIP)
binary.Write(h, binary.BigEndian, dstPort)
} else {
h.Write(dstIP)
binary.Write(h, binary.BigEndian, dstPort)
h.Write(srcIP)
binary.Write(h, binary.BigEndian, srcPort)
}
binary.Write(h, binary.BigEndian, proto)
return base64.RawURLEncoding.EncodeToString(h.Sum(nil))
}
type Direction uint8
const (
// According to IPFIX flowDirection field definition
DirectionInbound Direction = iota
DirectionOutbound
)
var directionNames = map[Direction]string{
DirectionInbound: "inbound",
DirectionOutbound: "outbound",
}
func (l Direction) String() string {
name, found := directionNames[l]
if found {
return name
}
return "unknown (" + strconv.Itoa(int(l)) + ")"
}