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.201107110845 contains the data from July 11th 2011 08:45 onward.
17 Netflow version v1, v5, v7 and v9 and IPFIX are transparently sup‐
19 ported.
20 Extensions: nfcapd supports a large number of v9 tags. In order to
22 optimise disk space and performance, v9 tags are grouped into a number
23 of extensions which may or may not be stored into the data file. There‐
24 fore the v9 templates configured on the exporter may be tuned according
25 the collector. Only those tags common to both are stored into the data
26 files.
27 Sampling: By default, the sampling rate is set to 1 (unsampled) or to
29 any given value specified by the -s cmd line option. If sampling infor‐
30 mation is found in the netflow stream, it overwrites the default value.
31 Sampling is automatically recognised when announced in v9 option tem‐
32 plates (tags #34, #35 or #48, #49, #50 ) or in the unofficial v5 header
33 hack. Note: Not all platforms (or IOS/JunOS versions) support export‐
34 ing sampling information in netflow data, even if sampling is config‐
35 ured. The number of bytes/packets in each netflow record is automati‐
36 cally multiplied by the sampling rate. The total number of flows is
37 not changed as this is not accurate enough. (Small flows versus large
38 flows) If the default sampling rate given by -s is negative, this will
39 hard overwrite any device specific announced sampling rates.
40 NSEL/ASA Support: nfcapd can be compiled with NSEL/ASA support
42 included. See notes on NSEL/ASA
43 NEL (NAT Event logging): nfcapd can be compiled with CISCO NEL support
45 included. See notes on NEL.
46
48 -p portnum
49 Specifies the port number to listen. Default port is 9995
50 -b bindhost
52 Specifies the hostname/IPv4/IPv6 address to bind for listening. This
53 can be an IP address or a hostname, resolving to an IP address
54 attached to an interface. Defaults to any available IPv4 interface,
55 if not specified.
56 -4 Forces nfcapd to listen on IPv4 addresses only. Can be used together
58 with -b if a hostname has an IPv4 and IPv6 address record.
59 -6 Forces nfcapd to listen on IPv6 addresses only. Can be used together
61 with -b if a hostname has an IPv4 and IPv6 address record. Depending
62 on the socket implementation -6 also accepts IPv4 data.
63 -J MulticastGroup
65 Join the specified IPv4 or IPv6 multicast group for listening.
66 -R host[/port}
68 Enable packet repeater. Send all incoming packets to another host
69 and port. host is either a valid IPv4/IPv6 address, or a valid sym‐
70 bolic hostname, which resolves to a IPv6 or IPv4 address. port may
71 be omitted and defaults to port 9995. Note: Due to IPv4/IPv6
72 accepted addresses the port separator is '/'. Up to 8 repeaters my
73 be defined.
74 -I IdentString ( capital letter i )
76 Specifies an ident string, which describes the source e.g. the name
77 of the router. This string is put into the stat record to identify
78 the source. Default is 'none'. This is for compatibility with nfdump
79 1.5.x and used to specify a single netflow source. See -n
80 -l base_directory ( letter ell )
82 Specifies the base directory to store the output files. If a sub
83 hierarchy is specified with -S the final directory is concatenated
84 to base_directory/sub_hierarchy. This is for compatibility with
85 nfdump 1.5.x and used to specify a single netflow source. See -n
86 -n <Ident,IP,base_directory>
88 Configures a netflow source named Ident and identified by source IP
89 address IP. The base directory for the flow files is base_direc‐
90 tory. If a sub hierarchy is specified with -S the final directory is
91 concatenated to base_directory/sub_hierarchy. Multiple netflow
92 sources can be specified. All data is sent to the same port speci‐
93 fied by -p. Note: You must not mix -n option with -I and -l. Use
94 either syntax.
95 -M <dynbase_directory>
97 Specifies the base directory to store the output files. In contrast
98 to -l -M allows to add dynamically new flow sources (exporters), as
99 they appear. All exporters send netflow data to the same port and
100 IP. For each dynamically added source, a new directory is created
101 with the name of the IPv4/IPv6 address of the exporter. All '.' and
102 ':" in IP addresses are replaced be '-' e.g. 10.11.12.13 is con‐
103 verted to the directory name 10-11-12-13. Note: Please make sure to
104 restrict at host level the potential range of IP addresses which are
105 allowed to connect to nfcapd. Otherwise you risk a potential DoS
106 attack on nfcapd, as nfcapd has no built in restrictions.
107 -f <pcap_file>
109 Read netflow packets from a give pcap_file instead of the network.
110 This requires nfcapd to be compiled with the pcap option and is
111 intended for debugging only.
112 -s <rate>
114 Apply default sampling rate rate to all netflow records, unless the
115 sampling rate is announced by the exporting device. In that case the
116 announced sampling rate is applied. If <rate> is negative, this will
117 hard overwrite any device specific announced sampling rates.
118 -S <num>
120 Allows to specify an additional directory sub hierarchy to store the
121 data files. The default is 0, no sub hierarchy, which means the
122 files go directly in the base directory (-l). The base directory
123 (-l) is concatenated with the specified sub hierarchy format to form
124 the final data directory. The following hierarchies are defined:
125 0 default no hierarchy levels
126 1 %Y/%m/%d year/month/day
127 2 %Y/%m/%d/%H year/month/day/hour
128 3 %Y/%W/%u year/week_of_year/day_of_week
129 4 %Y/%W/%u/%H year/week_of_year/day_of_week/hour
130 5 %Y/%j year/day-of-year
131 6 %Y/%j/%H year/day-of-year/hour
132 7 %Y-%m-%d year-month-day
133 8 %Y-%m-%d/%H year-month-day/hour
134 -T <extension list>
136 Specifies the list of extensions, to be stored in the netflow file.
137 Regardless of the extension list, the following netflow data is
138 stored per record: first, last, fwd status, tcp flags, proto,
139 (src)tos, src port, dst port, src ipaddr, dst ipaddr, in(packets),
140 in(bytes). In addition nfcapd recognises the extensions as described
141 below. Some are valid for v5/v7/v9, but most of them make only sense
142 for v9. Any specified extensions which do not exist in the input
143 netflow records are ignored.
144 Extensions:
146 v5/v7/v9/IPFIX extensions:
147 1 input/output interface SNMP numbers.
148 2 src/dst AS numbers.
149 3 src/dst mask, (dst)TOS, direction.
150 4 line Next hop IP addr line
151 5 line BGP next hop IP addr line
152 6 src/dst vlan id labels
153 7 counter output packets
154 8 counter output bytes
155 9 counter aggregated flows
156 10 in_src/out_dst MAC address
157 11 in_dst/out_src MAC address
158 12 MPLS labels 1-10
159 13 Exporting router IPv4/IPv6 address
160 14 Exporting router ID
161 15 BGP adjacent prev/next AS
162 16 time stamp flow received by the collector
163 NSEL/ASA/NAT extensions
164 26 NSEL ASA event, xtended event, ICMP type/code
165 27 NSEL/NAT xlate ports
166 28 NSEL/NAT xlate IPv4/IPv6 addr
167 29 NSEL ASA ACL ingress/egress acl ID
168 30 NSEL ASA username
169 NEL/NAT extensions
170 31 NAT event, ingress egress vrfid
171 32 NAT Block port allocation - block start, end step and size
172 latency extension
173 64 nfpcapd/nprobe client/server/application latency"},
174 IMPORTANT: By default only extension 1 and 2 are selected Exten‐
176 sions can be added/deleted by specifying a ',' separated list of
177 extension ids. Each id may be prepended by an optional sign +/- to
178 add or remove a given id from the extension list. Shortcuts: The
179 string 'all' means all extensions. The strings
180 'nsel' and 'nel' enable all NSEL or NEL extensions respectively.
181 Examples:
183 -T all Enables all possible extensions.
184 -T +3,+4 Adds extensions 3 and 4 to the defaults 1 and 2.
185 -T all,-8,-9 Set all extensions but 8 and 9
186 -T -1,4 Removes default extension 1 and adds extension 4
187 -T nsel Enables all required ASA?NSEL extensions
188 -T nel Enables all required nell extensions
189 Note: Only those tags in common with the exporting device and
190 enabled extensions at the collector side are stored into the data
191 files. A detailed list which v9 tags are mapped into which exten‐
192 sions is given in the section NOTES
193 -t interval
195 Specifies the time interval in seconds to rotate files. The default
196 value is 300s ( 5min ).
197 -w Align file rotation with next n minute ( specified by -t ) interval.
199 Example: If interval is 5 min, sync at 0,5,10... wall clock minutes
200 Default: no alignment.
201 -x cmd
203 Run command cmd at the end of every interval, when a new file
204 becomes available. The following command expansion is available:
205 %f Replaced by the file name e.g nfcapd.200907110845 inluding any
206 sub hierarchy. ( 2009/07/11/nfcapd.200907110845 )
207 %d Replaced by the directory where the file is located.
208 %t Replaced by the time ISO format e.g. 200907110845.
209 %u Replaced by the UNIX time format.
210 %i Replaced ident string given by -I
211 -X Collect and embed extended statistics. Currently a port and bpp his‐
213 togram is embedded. Mostly experimental for now
214 -e Auto expire files at every cycle. max lifetime and max filesize are
216 defined using nfexpire(1)
217 -P pidfile
219 Specify name of pidfile. Default is no pidfile.
220 -D Daemon mode: fork to background and detach from terminal. Nfcapd
222 terminates on signal TERM, INT and HUP.
223 -u userid
225 Change to the user userid as soon as possible. Only root is allowed
226 to use this option.
227 -g groupid
229 Change to the group groupid as soon as possible. Only root is
230 allowed use this option.
231 -B bufflen
233 Specifies the socket input buffer length in bytes. For high volume
234 traffic ( near GB traffic ) it is recommended to set this value as
235 high as possible ( typically > 100k ), otherwise you risk to lose
236 packets. The default is OS ( and kernel ) dependent.
237 -E Print netflow records in nfdump raw format to stdout. This option is
239 for debugging purpose only, to see how incoming netflow data is pro‐
240 cessed and stored.
241 -j Compress flows. Use bz2 compression in output file. Note: not recom‐
243 mended while collecting
244 -y Compress flows. Use LZ4 compression in output file.
246 -z Compress flows. Use fast LZO1X-1 compression in output file.
248 -V Print nfcapd version and exit.
250 -h Print help text to stdout with all options and exit.
252
254 Returns 0 on success, or 255 if initialization failed.
255
257 nfcapd logs to syslog with SYSLOG_FACILITY LOG_DAEMON For normal opera‐
258 tion level 'warning' should be fine. More information is reported at
259 level 'info' and 'debug'.
260 A small statistic about the collected flows, as well as errors are
262 reported at the end of every interval to syslog with level 'info'.
263
265 All flows are sent to port 9995 from all exporters and stored into a
266 single file. All known v9 tags are taken.
267 nfcapd -z -w -D -T all -l /netflow/spool/allflows -I any -S 2 -P
268 /var/run/nfcapd.allflows.pid
269 All flows from 2 different exporters are sent to port 8877 and stored
271 in separate directory trees. All known v9 tags are taken. Input buffer
272 size is set to 128000 bytes
273 nfcapd -z -w -D -T all -p 8877 -n upstream,192.168.1.1,/net‐
274 flow/spool/upstream -n peer,192.168.2.1,/netflow/spool/peer -S 2
275 -B 128000
276 Only accept from from a single exporter and only extension 3,4 and 5
278 are accepted. Run a given command when files are rotated and automati‐
279 cally expire flows:
280 nfcapd -w -D -T 3,4,5 -n upstream,192.168.1.1,/net‐
281 flow/spool/upstream -p 23456 -B 128000 -s 100 -x '/path/command
282 -r %d/%f' -P /var/run/nfcapd/nfcapd.pid -e
283
285 Multiple netflow sources:
286 Netflow data may be sent from different exporters to a single nfcapd
288 process. Use the -n option to separate each netflow source to a dif‐
289 ferent data directory. For compatibility with nfdump 1.5.x, old style
290 -l/-I options are still valid. In that case all flows from all sources
291 are stored in a single file. For high volume netflow streams, it is
292 still recommended to have a single nfcapd process per netflow source.
293 The current v9 implementation of nfdump supports the following v9 ele‐
295 ments: fields:
296 v9 element v9 ID Extension
297 NF9_LAST_SWITCHED 21 default
298 NF9_FIRST_SWITCHED 22 default
299 NF9_IN_BYTES 1 default
300 NF9_IN_PACKETS 2 default
301 NF9_IN_PROTOCOL 4 default
302 NF9_SRC_TOS 5 default
303 NF9_TCP_FLAGS 6 default
304 NF9_FORWARDING_STATUS 89 default
305 NF9_IPV4_SRC_ADDR 8 default
306 NF9_IPV4_DST_ADDR 12 default
307 NF9_IPV6_SRC_ADDR 27 default
308 NF9_IPV6_DST_ADDR 28 default
309 NF9_L4_SRC_PORT 7 default
310 NF9_L4_DST_PORT 11 default
311 NF9_ICMP_TYPE 32 default
312 NF9_INPUT_SNMP 10 1
313 NF9_OUTPUT_SNMP 14 1
314 NF9_SRC_AS 16 2
315 NF9_DST_AS 17 2
316 NF9_DST_TOS 55 3
317 NF9_DIRECTION 61 3
318 NF9_SRC_MASK 9 3
319 NF9_DST_MASK 13 3
320 NF9_IPV6_SRC_MASK 29 3
321 NF9_IPV6_DST_MASK 30 3
322 NF9_V4_NEXT_HOP 15 4
323 NF9_V6_NEXT_HOP 62 4
324 NF9_BGP_V4_NEXT_HOP 18 5
325 NF9_BPG_V6_NEXT_HOP 63 5
326 NF9_SRC_VLAN 58 6
327 NF9_DST_VLAN 59 6
328 NF9_OUT_PKTS 24 7
329 NF9_OUT_BYTES 23 8
330 NF9_FLOWS_AGGR 3 9
331 NF9_IN_SRC_MAC 56 10
332 NF9_OUT_DST_MAC 57 10
333 NF9_IN_DST_MAC 80 11
334 NF9_OUT_SRC_MAC 81 11
335 NF9_MPLS_LABEL_1 70 12
336 NF9_MPLS_LABEL_2 71 12
337 NF9_MPLS_LABEL_3 72 12
338 NF9_MPLS_LABEL_4 73 12
339 NF9_MPLS_LABEL_5 74 12
340 NF9_MPLS_LABEL_6 75 12
341 NF9_MPLS_LABEL_7 76 12
342 NF9_MPLS_LABEL_8 77 12
343 NF9_MPLS_LABEL_9 78 12
344 NF9_MPLS_LABEL_10 79 12
345 NF9_SAMPLING_INTERVAL 34 Sampling
346 NF9_SAMPLING_ALGORITHM 35 Sampling
347 NF9_FLOW_SAMPLER_ID 48 Sampling
348 FLOW_SAMPLER_MODE 49 Sampling
349 NF9_FLOW_SAMPLER_RANDOM_INTERVAL 50 Sampling
350 IP addr of exporting router 13
351 NF9_ENGINE_TYPE 38 14
352 NF9_ENGINE_ID 39 14
353 NF9_BGP_ADJ_NEXT_AS 128 15
354 NF9_BGP_ADJ_PREV_AS 129 15
355 collector received timestamp 16
356 32 and 64 bit are supported for all counters. 32it AS numbers are sup‐
357 ported.
358 IPFIX support is experimental. Due to lack of implementation of sam‐
360 pling in many IPFIX exporters, sampling for IPFIX is not yet supported.
361 The format of the data files is netflow version independent.
363 Socket buffer: Setting the socket buffer size is system dependent.
365 When starting up, nfcapd returns the number of bytes the buffer was
366 actually set. This is done by reading back the buffer size and may dif‐
367 fer from what you requested.
368
370 nfdump(1), nfprofile(1), nfreplay(1)
371
373 No software without bugs! Please report any bugs back to me.
374 2009-09-09 nfcapd(1)