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 '/'.
73 -I IdentString ( capital letter i )
75 Specifies an ident string, which describes the source e.g. the name
76 of the router. This string is put into the stat record to identify
77 the source. Default is 'none'. This is for compatibility with nfdump
78 1.5.x and used to specify a single netflow source. See -n
79 -l base_directory ( letter ell )
81 Specifies the base directory to store the output files. If a sub
82 hierarchy is specified with -S the final directory is concatenated
83 to base_directory/sub_hierarchy. This is for compatibility with
84 nfdump 1.5.x and used to specify a single netflow source. See -n
85 -n <Ident,IP,base_directory>
87 Configures a netflow source named Ident and identified by source IP
88 address IP. The base directory for the flow files is base_direc‐
89 tory. If a sub hierarchy is specified with -S the final directory is
90 concatenated to base_directory/sub_hierarchy. Multiple netflow
91 sources can be specified. All data is sent to the same port speci‐
92 fied by -p. Note: You must not mix -n option with -I and -l. Use
93 either syntax.
94 -M <dynbase_directory>
96 Specifies the base directory to store the output files. In contrast
97 to -l -M allows to add dynamically new flow sources (exporters), as
98 they appear. All exporters send netflow data to the same port and
99 IP. For each dynamically added source, a new directory is created
100 with the name of the IPv4/IPv6 address of the exporter. All '.' and
101 ':" in IP addresses are replaced be '-' e.g. 10.11.12.13 is con‐
102 verted to the directory name 10-11-12-13. Note: Please make sure to
103 restrict at host level the potential range of IP addresses which are
104 allowed to connect to nfcapd. Otherwise you risk a potential DoS
105 attack on nfcapd, as nfcapd has no built in restrictions.
106 -f <pcap_file>
108 Read netflow packets from a give pcap_file instead of the network.
109 This requires nfcapd to be compiled with the pcap option and is
110 intended for debugging only.
111 -s <rate>
113 Apply default sampling rate rate to all netflow records, unless the
114 sampling rate is announced by the exporting device. In that case the
115 announced sampling rate is applied. If <rate> is negative, this will
116 hard overwrite any device specific announced sampling rates.
117 -S <num>
119 Allows to specify an additional directory sub hierarchy to store the
120 data files. The default is 0, no sub hierarchy, which means the
121 files go directly in the base directory (-l). The base directory
122 (-l) is concatenated with the specified sub hierarchy format to form
123 the final data directory. The following hierarchies are defined:
124 0 default no hierarchy levels
125 1 %Y/%m/%d year/month/day
126 2 %Y/%m/%d/%H year/month/day/hour
127 3 %Y/%W/%u year/week_of_year/day_of_week
128 4 %Y/%W/%u/%H year/week_of_year/day_of_week/hour
129 5 %Y/%j year/day-of-year
130 6 %Y/%j/%H year/day-of-year/hour
131 7 %Y-%m-%d year-month-day
132 8 %Y-%m-%d/%H year-month-day/hour
133 -T <extension list>
135 Specifies the list of extensions, to be stored in the netflow file.
136 Regardless of the extension list, the following netflow data is
137 stored per record: first, last, fwd status, tcp flags, proto,
138 (src)tos, src port, dst port, src ipaddr, dst ipaddr, in(packets),
139 in(bytes). In addition nfcapd recognises the extensions as described
140 below. Some are valid for v5/v7/v9, but most of them make only sense
141 for v9. Any specified extensions which do not exist in the input
142 netflow records are ignored.
143 Extensions:
145 v5/v7/v9/IPFIX extensions:
146 1 input/output interface SNMP numbers.
147 2 src/dst AS numbers.
148 3 src/dst mask, (dst)TOS, direction.
149 4 line Next hop IP addr line
150 5 line BGP next hop IP addr line
151 6 src/dst vlan id labels
152 7 counter output packets
153 8 counter output bytes
154 9 counter aggregated flows
155 10 in_src/out_dst MAC address
156 11 in_dst/out_src MAC address
157 12 MPLS labels 1-10
158 13 Exporting router IPv4/IPv6 address
159 14 Exporting router ID
160 15 BGP adjacent prev/next AS
161 16 time stamp flow received by the collector
162 NSEL/ASA/NAT extensions
163 26 NSEL ASA event, xtended event, ICMP type/code
164 27 NSEL/NAT xlate ports
165 28 NSEL/NAT xlate IPv4/IPv6 addr
166 29 NSEL ASA ACL ingress/egress acl ID
167 30 NSEL ASA username
168 NEL/NAT extensions
169 31 NAT event, ingress egress vrfid
170 32 NAT Block port allocation - block start, end step and size
171 latency extension
172 64 nfpcapd/nprobe client/server/application latency"},
173 IMPORTANT: By default only extension 1 and 2 are selected Exten‐
175 sions can be added/deleted by specifying a ',' separated list of
176 extension ids. Each id may be prepended by an optional sign +/- to
177 add or remove a given id from the extension list. Shortcuts: The
178 string 'all' means all extensions. The strings
179 'nsel' and 'nel' enable all NSEL or NEL extensions respectively.
180 Examples:
182 -T all Enables all possible extensions.
183 -T +3,+4 Adds extensions 3 and 4 to the defaults 1 and 2.
184 -T all,-8,-9 Set all extensions but 8 and 9
185 -T -1,4 Removes default extension 1 and adds extension 4
186 -T nsel Enables all required ASA?NSEL extensions
187 -T nel Enables all required nell extensions
188 Note: Only those tags in common with the exporting device and
189 enabled extensions at the collector side are stored into the data
190 files. A detailed list which v9 tags are mapped into which exten‐
191 sions is given in the section NOTES
192 -t interval
194 Specifies the time interval in seconds to rotate files. The default
195 value is 300s ( 5min ).
196 -w Align file rotation with next n minute ( specified by -t ) interval.
198 Example: If interval is 5 min, sync at 0,5,10... wall clock minutes
199 Default: no alignment.
200 -x cmd
202 Run command cmd at the end of every interval, when a new file
203 becomes available. The following command expansion is available:
204 %f Replaced by the file name e.g nfcapd.200907110845 inluding any
205 sub hierarchy. ( 2009/07/11/nfcapd.200907110845 )
206 %d Replaced by the directory where the file is located.
207 %t Replaced by the time ISO format e.g. 200907110845.
208 %u Replaced by the UNIX time format.
209 %i Replaced ident string given by -I
210 -X Collect and embed extended statistics. Currently a port and bpp his‐
212 togram is embedded. Mostly experimental for now
213 -e Auto expire files at every cycle. max lifetime and max filesize are
215 defined using nfexpire(1)
216 -P pidfile
218 Specify name of pidfile. Default is no pidfile.
219 -D Daemon mode: fork to background and detach from terminal. Nfcapd
221 terminates on signal TERM, INT and HUP.
222 -u userid
224 Change to the user userid as soon as possible. Only root is allowed
225 to use this option.
226 -g groupid
228 Change to the group groupid as soon as possible. Only root is
229 allowed use this option.
230 -B bufflen
232 Specifies the socket input buffer length in bytes. For high volume
233 traffic ( near GB traffic ) it is recommended to set this value as
234 high as possible ( typically > 100k ), otherwise you risk to lose
235 packets. The default is OS ( and kernel ) dependent.
236 -E Print netflow records in nfdump raw format to stdout. This option is
238 for debugging purpose only, to see how incoming netflow data is pro‐
239 cessed and stored.
240 -j Compress flows. Use bz2 compression in output file. Note: not recom‐
242 mended while collecting
243 -y Compress flows. Use LZ4 compression in output file.
245 -z Compress flows. Use fast LZO1X-1 compression in output file.
247 -V Print nfcapd version and exit.
249 -h Print help text to stdout with all options and exit.
251
253 Returns 0 on success, or 255 if initialization failed.
254
256 nfcapd logs to syslog with SYSLOG_FACILITY LOG_DAEMON For normal opera‐
257 tion level 'warning' should be fine. More information is reported at
258 level 'info' and 'debug'.
259 A small statistic about the collected flows, as well as errors are
261 reported at the end of every interval to syslog with level 'info'.
262
264 All flows are sent to port 9995 from all exporters and stored into a
265 single file. All known v9 tags are taken.
266 nfcapd -z -w -D -T all -l /netflow/spool/allflows -I any -S 2 -P
267 /var/run/nfcapd.allflows.pid
268 All flows from 2 different exporters are sent to port 8877 and stored
270 in separate directory trees. All known v9 tags are taken. Input buffer
271 size is set to 128000 bytes
272 nfcapd -z -w -D -T all -p 8877 -n upstream,192.168.1.1,/net‐
273 flow/spool/upstream -n peer,192.168.2.1,/netflow/spool/peer -S 2
274 -B 128000
275 Only accept from from a single exporter and only extension 3,4 and 5
277 are accepted. Run a given command when files are rotated and automati‐
278 cally expire flows:
279 nfcapd -w -D -T 3,4,5 -n upstream,192.168.1.1,/net‐
280 flow/spool/upstream -p 23456 -B 128000 -s 100 -x '/path/command
281 -r %d/%f' -P /var/run/nfcapd/nfcapd.pid -e
282
284 Multiple netflow sources:
285 Netflow data may be sent from different exporters to a single nfcapd
287 process. Use the -n option to separate each netflow source to a dif‐
288 ferent data directory. For compatibility with nfdump 1.5.x, old style
289 -l/-I options are still valid. In that case all flows from all sources
290 are stored in a single file. For high volume netflow streams, it is
291 still recommended to have a single nfcapd process per netflow source.
292 The current v9 implementation of nfdump supports the following v9 ele‐
294 ments: fields:
295 v9 element v9 ID Extension
296 NF9_LAST_SWITCHED 21 default
297 NF9_FIRST_SWITCHED 22 default
298 NF9_IN_BYTES 1 default
299 NF9_IN_PACKETS 2 default
300 NF9_IN_PROTOCOL 4 default
301 NF9_SRC_TOS 5 default
302 NF9_TCP_FLAGS 6 default
303 NF9_FORWARDING_STATUS 89 default
304 NF9_IPV4_SRC_ADDR 8 default
305 NF9_IPV4_DST_ADDR 12 default
306 NF9_IPV6_SRC_ADDR 27 default
307 NF9_IPV6_DST_ADDR 28 default
308 NF9_L4_SRC_PORT 7 default
309 NF9_L4_DST_PORT 11 default
310 NF9_ICMP_TYPE 32 default
311 NF9_INPUT_SNMP 10 1
312 NF9_OUTPUT_SNMP 14 1
313 NF9_SRC_AS 16 2
314 NF9_DST_AS 17 2
315 NF9_DST_TOS 55 3
316 NF9_DIRECTION 61 3
317 NF9_SRC_MASK 9 3
318 NF9_DST_MASK 13 3
319 NF9_IPV6_SRC_MASK 29 3
320 NF9_IPV6_DST_MASK 30 3
321 NF9_V4_NEXT_HOP 15 4
322 NF9_V6_NEXT_HOP 62 4
323 NF9_BGP_V4_NEXT_HOP 18 5
324 NF9_BPG_V6_NEXT_HOP 63 5
325 NF9_SRC_VLAN 58 6
326 NF9_DST_VLAN 59 6
327 NF9_OUT_PKTS 24 7
328 NF9_OUT_BYTES 23 8
329 NF9_FLOWS_AGGR 3 9
330 NF9_IN_SRC_MAC 56 10
331 NF9_OUT_DST_MAC 57 10
332 NF9_IN_DST_MAC 80 11
333 NF9_OUT_SRC_MAC 81 11
334 NF9_MPLS_LABEL_1 70 12
335 NF9_MPLS_LABEL_2 71 12
336 NF9_MPLS_LABEL_3 72 12
337 NF9_MPLS_LABEL_4 73 12
338 NF9_MPLS_LABEL_5 74 12
339 NF9_MPLS_LABEL_6 75 12
340 NF9_MPLS_LABEL_7 76 12
341 NF9_MPLS_LABEL_8 77 12
342 NF9_MPLS_LABEL_9 78 12
343 NF9_MPLS_LABEL_10 79 12
344 NF9_SAMPLING_INTERVAL 34 Sampling
345 NF9_SAMPLING_ALGORITHM 35 Sampling
346 NF9_FLOW_SAMPLER_ID 48 Sampling
347 FLOW_SAMPLER_MODE 49 Sampling
348 NF9_FLOW_SAMPLER_RANDOM_INTERVAL 50 Sampling
349 IP addr of exporting router 13
350 NF9_ENGINE_TYPE 38 14
351 NF9_ENGINE_ID 39 14
352 NF9_BGP_ADJ_NEXT_AS 128 15
353 NF9_BGP_ADJ_PREV_AS 129 15
354 collector received timestamp 16
355 32 and 64 bit are supported for all counters. 32it AS numbers are sup‐
356 ported.
357 IPFIX support is experimental. Due to lack of implementation of sam‐
359 pling in many IPFIX exporters, sampling for IPFIX is not yet supported.
360 The format of the data files is netflow version independent.
362 Socket buffer: Setting the socket buffer size is system dependent.
364 When starting up, nfcapd returns the number of bytes the buffer was
365 actually set. This is done by reading back the buffer size and may dif‐
366 fer from what you requested.
367
369 nfdump(1), nfprofile(1), nfreplay(1)
370
372 No software without bugs! Please report any bugs back to me.
373 2009-09-09 nfcapd(1)