1nfcapd(1) nfcapd(1)
2
6 nfcapd - netflow capture daemon
7
9 nfcapd [options]
10
12 nfcapd is the netflow capture daemon of the nfdump tools. It reads net‐
13 flow data from the network and stores it into files. The output file is
14 automatically rotated and renamed every n minutes - typically 5 min -
15 according the timestamp YYYYMMddhhmm of the interval e.g.
16 nfcapd.201907110845 contains the data from July 11th 2019 08:45 onward.
17 If the time interval is smaller then 60s, the naming extends to seconds
18 e.g. nfcapd.20190711084510.
19 Netflow version v1, v5, v7 and v9 and IPFIX are transparently sup‐
22 ported.
23 Extensions: nfcapd supports a large number of v9 tags. In order to
25 optimise disk space and performance, v9 tags are grouped into a number
26 of extensions which may or may not be stored into the data file. There‐
27 fore the v9 templates configured on the exporter may be tuned according
28 the collector. Only those tags common to both are stored into the data
29 files.
30 Sampling: By default, the sampling rate is set to 1 (unsampled) or to
32 any given value specified by the -s cmd line option. If sampling infor‐
33 mation is found in the netflow stream, it overwrites the default value.
34 Sampling is automatically recognised when announced in v9 option tem‐
35 plates (tags #34, #35 or #48, #49, #50 ) or in the unofficial v5 header
36 hack. Note: Not all platforms (or IOS/JunOS versions) support export‐
37 ing sampling information in netflow data, even if sampling is config‐
38 ured. The number of bytes/packets in each netflow record is automati‐
39 cally multiplied by the sampling rate. The total number of flows is
40 not changed as this is not accurate enough. (Small flows versus large
41 flows) If the default sampling rate given by -s is negative, this will
42 hard overwrite any device specific announced sampling rates.
43 NSEL/ASA Support: nfcapd can be compiled with NSEL/ASA support
45 included. See notes on NSEL/ASA
46 NEL (NAT Event logging): nfcapd can be compiled with CISCO NEL support
48 included. See notes on NEL.
49
51 -p portnum
52 Specifies the port number to listen. Default port is 9995
53 -b bindhost
55 Specifies the hostname/IPv4/IPv6 address to bind for listening. This
56 can be an IP address or a hostname, resolving to an IP address
57 attached to an interface. Defaults to any available IPv4 interface,
58 if not specified.
59 -4 Forces nfcapd to listen on IPv4 addresses only. Can be used together
61 with -b if a hostname has an IPv4 and IPv6 address record.
62 -6 Forces nfcapd to listen on IPv6 addresses only. Can be used together
64 with -b if a hostname has an IPv4 and IPv6 address record. Depending
65 on the socket implementation -6 also accepts IPv4 data.
66 -J MulticastGroup
68 Join the specified IPv4 or IPv6 multicast group for listening.
69 -R host[/port}
71 Enable packet repeater. Send all incoming packets to another host
72 and port. host is either a valid IPv4/IPv6 address, or a valid sym‐
73 bolic hostname, which resolves to a IPv6 or IPv4 address. port may
74 be omitted and defaults to port 9995. Note: Due to IPv4/IPv6
75 accepted addresses the port separator is '/'. Up to 8 repeaters my
76 be defined.
77 -I IdentString ( capital letter i )
79 Specifies an ident string, which describes the source e.g. the name
80 of the router. This string is put into the stat record to identify
81 the source. Default is 'none'. This is for compatibility with nfdump
82 1.5.x and used to specify a single netflow source. See -n
83 -l base_directory ( letter ell )
85 Specifies the base directory to store the output files. If a sub
86 hierarchy is specified with -S the final directory is concatenated
87 to base_directory/sub_hierarchy. This is for compatibility with
88 nfdump 1.5.x and used to specify a single netflow source. See -n
89 -n <Ident,IP,base_directory>
91 Configures a netflow source named Ident and identified by source IP
92 address IP. The base directory for the flow files is base_direc‐
93 tory. If a sub hierarchy is specified with -S the final directory is
94 concatenated to base_directory/sub_hierarchy. Multiple netflow
95 sources can be specified. All data is sent to the same port speci‐
96 fied by -p. Note: You must not mix -n option with -I and -l. Use
97 either syntax.
98 -N <file>
100 Specifies the file to read to add multiple netflow sources. The file
101 is expected to contain one netflow source per line based on the same
102 syntax than the -n option. Comments are not interpreted. Ident col‐
103 lision are not handled if -N is specified multiple times.
104 -M <dynbase_directory>
106 Specifies the base directory to store the output files. In contrast
107 to -l -M allows to add dynamically new flow sources (exporters), as
108 they appear. All exporters send netflow data to the same port and
109 IP. For each dynamically added source, a new directory is created
110 with the name of the IPv4/IPv6 address of the exporter. All '.' and
111 ':" in IP addresses are replaced be '-' e.g. 10.11.12.13 is con‐
112 verted to the directory name 10-11-12-13. Note: Please make sure to
113 restrict at host level the potential range of IP addresses which are
114 allowed to connect to nfcapd. Otherwise you risk a potential DoS
115 attack on nfcapd, as nfcapd has no built in restrictions.
116 -f <pcap_file>
118 Read netflow packets from a give pcap_file instead of the network.
119 This requires nfcapd to be compiled with the pcap option and is
120 intended for debugging only.
121 -s <rate>
123 Apply default sampling rate rate to all netflow records, unless the
124 sampling rate is announced by the exporting device. In that case the
125 announced sampling rate is applied. If <rate> is negative, this will
126 hard overwrite any device specific announced sampling rates.
127 -S <num>
129 Allows to specify an additional directory sub hierarchy to store the
130 data files. The default is 0, no sub hierarchy, which means the
131 files go directly in the base directory (-l). The base directory
132 (-l) is concatenated with the specified sub hierarchy format to form
133 the final data directory. The following hierarchies are defined:
134 0 default no hierarchy levels
135 1 %Y/%m/%d year/month/day
136 2 %Y/%m/%d/%H year/month/day/hour
137 3 %Y/%W/%u year/week_of_year/day_of_week
138 4 %Y/%W/%u/%H year/week_of_year/day_of_week/hour
139 5 %Y/%j year/day-of-year
140 6 %Y/%j/%H year/day-of-year/hour
141 7 %Y-%m-%d year-month-day
142 8 %Y-%m-%d/%H year-month-day/hour
143 -T <extension list>
145 Specifies the list of extensions, to be stored in the netflow file.
146 Regardless of the extension list, the following netflow data is
147 stored per record: first, last, fwd status, tcp flags, proto,
148 (src)tos, src port, dst port, src ipaddr, dst ipaddr, in(packets),
149 in(bytes). In addition nfcapd recognises the extensions as described
150 below. Some are valid for v5/v7/v9, but most of them make only sense
151 for v9. Any specified extensions which do not exist in the input
152 netflow records are ignored.
153 Extensions:
155 v5/v7/v9/IPFIX extensions:
156 1 input/output interface SNMP numbers.
157 2 src/dst AS numbers.
158 3 src/dst mask, (dst)TOS, direction.
159 4 line Next hop IP addr line
160 5 line BGP next hop IP addr line
161 6 src/dst vlan id labels
162 7 counter output packets
163 8 counter output bytes
164 9 counter aggregated flows
165 10 in_src/out_dst MAC address
166 11 in_dst/out_src MAC address
167 12 MPLS labels 1-10
168 13 Exporting router IPv4/IPv6 address
169 14 Exporting router ID
170 15 BGP adjacent prev/next AS
171 16 time stamp flow received by the collector
172 NSEL/ASA/NAT extensions
173 26 NSEL ASA event, xtended event, ICMP type/code
174 27 NSEL/NAT xlate ports
175 28 NSEL/NAT xlate IPv4/IPv6 addr
176 29 NSEL ASA ACL ingress/egress acl ID
177 30 NSEL ASA username
178 NEL/NAT extensions
179 31 NAT event, ingress egress vrfid
180 32 NAT Block port allocation - block start, end step and size
181 latency extension
182 64 nfpcapd/nprobe client/server/application latency"},
183 IMPORTANT: By default only extension 1 and 2 are selected Exten‐
185 sions can be added/deleted by specifying a ',' separated list of
186 extension ids. Each id may be prepended by an optional sign +/- to
187 add or remove a given id from the extension list. Shortcuts: The
188 string 'all' means all extensions. The strings
189 'nsel' and 'nel' enable all NSEL or NEL extensions respectively.
190 Examples:
192 -T all Enables all possible extensions.
193 -T +3,+4 Adds extensions 3 and 4 to the defaults 1 and 2.
194 -T all,-8,-9 Set all extensions but 8 and 9
195 -T -1,4 Removes default extension 1 and adds extension 4
196 -T nsel Enables all required ASA?NSEL extensions
197 -T nel Enables all required nell extensions
198 Note: Only those tags in common with the exporting device and
199 enabled extensions at the collector side are stored into the data
200 files. A detailed list which v9 tags are mapped into which exten‐
201 sions is given in the section NOTES
202 -t interval
204 Specifies the time interval in seconds to rotate files. The default
205 value is 300s ( 5min ). The smallest interval is 2s.
206 -w Align file rotation with next n minute ( specified by -t ) interval.
208 Example: If interval is 5 min, sync at 0,5,10... wall clock minutes
209 Default: no alignment.
210 -x cmd
212 Run command cmd at the end of every interval, when a new file
213 becomes available. The following command expansion is available:
214 %f Replaced by the file name e.g nfcapd.200907110845 inluding any
215 sub hierarchy. ( 2009/07/11/nfcapd.200907110845 )
216 %d Replaced by the directory where the file is located.
217 %t Replaced by the time ISO format e.g. 200907110845.
218 %u Replaced by the UNIX time format.
219 %i Replaced ident string given by -I
220 -X Collect and embed extended statistics. Currently a port and bpp his‐
222 togram is embedded. Mostly experimental for now
223 -e Auto expire files at every cycle. max lifetime and max filesize are
225 defined using nfexpire(1)
226 -P pidfile
228 Specify name of pidfile. Default is no pidfile.
229 -D Daemon mode: fork to background and detach from terminal. Nfcapd
231 terminates on signal TERM, INT and HUP.
232 -u userid
234 Change to the user userid as soon as possible. Only root is allowed
235 to use this option.
236 -g groupid
238 Change to the group groupid as soon as possible. Only root is
239 allowed use this option.
240 -B bufflen
242 Specifies the socket input buffer length in bytes. For high volume
243 traffic ( near GB traffic ) it is recommended to set this value as
244 high as possible ( typically > 100k ), otherwise you risk to lose
245 packets. The default is OS ( and kernel ) dependent.
246 -E Print netflow records in nfdump raw format to stdout. This option is
248 for debugging purpose only, to see how incoming netflow data is pro‐
249 cessed and stored.
250 -j Compress flows. Use bz2 compression in output file. Note: not recom‐
252 mended while collecting
253 -y Compress flows. Use LZ4 compression in output file.
255 -z Compress flows. Use fast LZO1X-1 compression in output file.
257 -V Print nfcapd version and exit.
259 -h Print help text to stdout with all options and exit.
261
263 Returns 0 on success, or 255 if initialization failed.
264
266 nfcapd logs to syslog with SYSLOG_FACILITY LOG_DAEMON For normal opera‐
267 tion level 'warning' should be fine. More information is reported at
268 level 'info' and 'debug'.
269 A small statistic about the collected flows, as well as errors are
271 reported at the end of every interval to syslog with level 'info'.
272
274 All flows are sent to port 9995 from all exporters and stored into a
275 single file. All known v9 tags are taken.
276 nfcapd -z -w -D -T all -l /netflow/spool/allflows -I any -S 2 -P
277 /var/run/nfcapd.allflows.pid
278 All flows from 2 different exporters are sent to port 8877 and stored
280 in separate directory trees. All known v9 tags are taken. Input buffer
281 size is set to 128000 bytes
282 nfcapd -z -w -D -T all -p 8877 -n upstream,192.168.1.1,/net‐
283 flow/spool/upstream -n peer,192.168.2.1,/netflow/spool/peer -S 2
284 -B 128000
285 Only accept from from a single exporter and only extension 3,4 and 5
287 are accepted. Run a given command when files are rotated and automati‐
288 cally expire flows:
289 nfcapd -w -D -T 3,4,5 -n upstream,192.168.1.1,/net‐
290 flow/spool/upstream -p 23456 -B 128000 -s 100 -x '/path/command
291 -r %d/%f' -P /var/run/nfcapd/nfcapd.pid -e
292
294 Multiple netflow sources:
295 Netflow data may be sent from different exporters to a single nfcapd
297 process. Use the -n option to separate each netflow source to a dif‐
298 ferent data directory. For compatibility with nfdump 1.5.x, old style
299 -l/-I options are still valid. In that case all flows from all sources
300 are stored in a single file. For high volume netflow streams, it is
301 still recommended to have a single nfcapd process per netflow source.
302 The current v9 implementation of nfdump supports the following v9 ele‐
304 ments: fields:
305 v9 element v9 ID Extension
306 NF9_LAST_SWITCHED 21 default
307 NF9_FIRST_SWITCHED 22 default
308 NF9_IN_BYTES 1 default
309 NF9_IN_PACKETS 2 default
310 NF9_IN_PROTOCOL 4 default
311 NF9_SRC_TOS 5 default
312 NF9_TCP_FLAGS 6 default
313 NF9_FORWARDING_STATUS 89 default
314 NF9_IPV4_SRC_ADDR 8 default
315 NF9_IPV4_DST_ADDR 12 default
316 NF9_IPV6_SRC_ADDR 27 default
317 NF9_IPV6_DST_ADDR 28 default
318 NF9_L4_SRC_PORT 7 default
319 NF9_L4_DST_PORT 11 default
320 NF9_ICMP_TYPE 32 default
321 NF9_INPUT_SNMP 10 1
322 NF9_OUTPUT_SNMP 14 1
323 NF9_SRC_AS 16 2
324 NF9_DST_AS 17 2
325 NF9_DST_TOS 55 3
326 NF9_DIRECTION 61 3
327 NF9_SRC_MASK 9 3
328 NF9_DST_MASK 13 3
329 NF9_IPV6_SRC_MASK 29 3
330 NF9_IPV6_DST_MASK 30 3
331 NF9_V4_NEXT_HOP 15 4
332 NF9_V6_NEXT_HOP 62 4
333 NF9_BGP_V4_NEXT_HOP 18 5
334 NF9_BPG_V6_NEXT_HOP 63 5
335 NF9_SRC_VLAN 58 6
336 NF9_DST_VLAN 59 6
337 NF9_OUT_PKTS 24 7
338 NF9_OUT_BYTES 23 8
339 NF9_FLOWS_AGGR 3 9
340 NF9_IN_SRC_MAC 56 10
341 NF9_OUT_DST_MAC 57 10
342 NF9_IN_DST_MAC 80 11
343 NF9_OUT_SRC_MAC 81 11
344 NF9_MPLS_LABEL_1 70 12
345 NF9_MPLS_LABEL_2 71 12
346 NF9_MPLS_LABEL_3 72 12
347 NF9_MPLS_LABEL_4 73 12
348 NF9_MPLS_LABEL_5 74 12
349 NF9_MPLS_LABEL_6 75 12
350 NF9_MPLS_LABEL_7 76 12
351 NF9_MPLS_LABEL_8 77 12
352 NF9_MPLS_LABEL_9 78 12
353 NF9_MPLS_LABEL_10 79 12
354 NF9_SAMPLING_INTERVAL 34 Sampling
355 NF9_SAMPLING_ALGORITHM 35 Sampling
356 NF9_FLOW_SAMPLER_ID 48 Sampling
357 FLOW_SAMPLER_MODE 49 Sampling
358 NF9_FLOW_SAMPLER_RANDOM_INTERVAL 50 Sampling
359 IP addr of exporting router 13
360 NF9_ENGINE_TYPE 38 14
361 NF9_ENGINE_ID 39 14
362 NF9_BGP_ADJ_NEXT_AS 128 15
363 NF9_BGP_ADJ_PREV_AS 129 15
364 collector received timestamp 16
365 32 and 64 bit are supported for all counters. 32it AS numbers are sup‐
366 ported.
367 IPFIX support is experimental. Due to lack of implementation of sam‐
369 pling in many IPFIX exporters, sampling for IPFIX is not yet supported.
370 The format of the data files is netflow version independent.
372 Socket buffer: Setting the socket buffer size is system dependent.
374 When starting up, nfcapd returns the number of bytes the buffer was
375 actually set. This is done by reading back the buffer size and may dif‐
376 fer from what you requested.
377
379 nfdump(1), nfprofile(1), nfreplay(1)
380
382 No software without bugs! Please report any bugs back to me.
383 2009-09-09 nfcapd(1)