Hello,

I am facing a strange problem. Data is output from a Cisco 2951 router 
running IOS 15.5(1)T2.

I am getting logical data on other VLANs/Subinterfaces, but on a 
particular one, it seems crazy; Here is sample output for a 10-minute 
period:

# nfdump -M /data/nfsen/profiles-data/live/thi -R 
2016/07/29/nfcapd.201607291600:2016/07/29/nfcapd.201607291605 -s record 
-n 20 -o extended '(OUT IF 32)'
Aggregated flows 36
Top 20 flows ordered by -:
Date first seen          Duration Proto      Src IP Addr:Port          
Dst IP Addr:Port   Flags Tos  Packets Bytes      pps      bps    Bpp Flows
2016-06-10 14:40:30.888 8503167.515     0 5.6.235.243:0     ->        
1.187.0.0:1     U.....  72   83.9 M    6.7 G        9     6333     80     5
2016-07-17 02:49:07.496 2103455.182     0 3.6.113.214:0     ->        
1.187.0.0:1     U.....  61 0    4.0 G        0    15361      0     3
2016-08-06 07:29:37.960 3604220.443     0 14.6.183.167:0     ->        
1.187.0.0:1     U.....  72 335.5 M    2.7 G       93     5976      8     2
2016-08-17 18:27:13.704 1052721.476     0 3.6.197.188:0     ->        
1.187.0.0:2     U..... 185  167.8 M    2.7 G      159    20463     16     2
2016-08-01 20:18:21.992 1428778.913 IGMP 14.6.184.85:0     ->        
1.187.0.0:6     U.....  37  285.2 M    1.3 G      199     7538      4     1
2016-08-01 20:18:21.992 1428778.913     0 4.6.195.243:0     ->        
1.187.0.0:2     U..... 166   16.8 M    1.3 G       11     7538     80     1
2016-08-01 20:18:21.992 1428778.913 HMP 3.6.193.71:0     ->        
1.187.0.0:26    U.....  18 0    1.3 G        0     7538      0     1
2016-08-28 01:27:06.152 327159.723     0 7.6.231.162:0     ->        
1.187.0.0:2     U..... 190  352.3 M    1.3 G     1076    32922      3     1
2016-08-01 20:18:21.992 1428778.913 IGMP 4.6.195.243:0     ->        
1.187.0.0:6     U..... 113   16.8 M    1.3 G       11     7538     80     1
2016-08-01 20:18:21.992 1428778.913     0 3.6.202.119:0     ->        
1.187.0.0:3     U..... 181   50.3 M    1.3 G       35     7538     26     1
2016-07-27 19:08:14.376 473900.414 DDP 14.6.183.167:0     ->        
1.187.0.0:97    U.....  98 167.8 M    1.3 G      354    22728      8     1
2016-08-01 20:18:21.992 1428778.913     0 14.6.184.85:0     ->        
1.187.0.0:2     U..... 185  285.2 M    1.3 G      199     7538      4     1
2016-07-17 02:49:07.496 2103455.182     0 3.6.112.203:0     ->        
1.187.0.0:1     U.....  61 0    1.3 G        0     5120      0     1
2016-08-01 20:18:21.992 1428778.913 ICMP 1.6.198.67:0     ->        
1.187.0.0:0.7   U..... 222   16.8 M    1.3 G       11     7538     80     1
2016-08-01 20:11:49.884 1429171.021     0 3.6.202.110:0     ->        
1.187.0.0:1     U.....  61  201.3 M    4.2 M      140       23      0     1
2016-07-30 07:43:18.184 4208255.493 ICMP 4.6.195.243:0     ->        
1.187.0.0:0.3   U..... 141   16.8 M    1.3 G        3     2559     80     1
2016-06-28 01:59:48.220 2698771.352     0 3.6.202.110:0     ->        
1.187.0.0:3     U..... 181  201.3 M    4.2 M       74       12      0     1
2016-08-01 20:18:21.992 1428778.913 ICMP 14.6.193.78:0     ->        
1.187.0.0:0.6   U..... 106   50.3 M    1.3 G       35     7538     26     1
2016-07-27 19:08:14.376 473900.414     0 14.6.227.236:0     ->        
1.187.0.0:1     U.....  61 385.9 M    1.3 G      814    22728      3     1
2016-08-28 01:27:06.152 327159.723 BBN 13.6.199.108:0     ->        
1.187.0.0:14    U..... 163 83.9 M    1.3 G      256    32922     16     1
Summary: total flows: 44, total bytes: 56824511328, total packets: 
4127195136, avg bps: 53249, avg pps: 483, avg bpp: 13
Time window: Time Window unknown
Total flows processed: 39913, Blocks skipped: 0, Bytes read: 2556096
Sys: 0.009s flows/second: 3992098.4  Wall: 0.012s flows/second: 3153183.8

This absurd data clutters all nfsen diagrams.

All these IP Addresses are totally irrelevant to our network and the 
number of packets/bytes is unimaginable. It seems that nfdump 
misinterprets some netflow data.

I am using:

    # nfdump -V
    nfdump: Version: NSEL-NEL1.6.13

nfdump 1.6.13 was compiled as:

    ./configure --enable-nsel --enable-nfprofile --enable-nftrack
    --with-rrdpath=/usr/include

and nfsen:

    # /data/nfsen/bin/nfsen -V
    /data/nfsen/bin/nfsen: 1.3.6p1 $Id: nfsen 53 2012-01-23 16:36:02Z
    peter $

By viewing raw nfdump data, it seems that some records are wrong. For 
example, in the output of:

    # nfdump -M /data/nfsen/profiles-data/live/thi -c 200 -r
    2016/07/29/nfcapd.201607291640 -o raw | less

the first record is absolutely wrong (time, interfaces, etc):

Flow Record:
   Flags        =              0x06 FLOW, Unsampled
   export sysid =                 2
   size         =                64
   first        =        1470300950 [2016-08-04 11:55:50]
   last         =        1470304097 [2016-08-04 12:48:17]
   msec_first   =               308
   msec_last    =               628
   src addr     =         227.0.0.7
   dst addr     =          55.0.0.0
   src port     =             61120
   dst port     =              2049
   fwd status   =                 0
   tcp flags    =              0x11 .A...F
   proto        =                15 XNET
   (src)tos     =                 1
   (in)packets  =               565
   (in)bytes    =                 0
   input        =              1656
   output       =             45827
   src as       =             23751
   dst as       =               520

It is followed by about 50 correct records and then two wrong ones show up:

Flow Record:
   Flags        =              0x06 FLOW, Unsampled
   export sysid =                 2
   size         =                64
   first        =        1466547443 [2016-06-22 01:17:23]
   last         =        1470471807 [2016-08-06 11:23:27]
   msec_first   =               481
   msec_last    =               844
   src addr     =       187.0.2.210
   dst addr     =           3.0.0.7
   src port     =             60941
   dst port     =             40961
   fwd status   =                 0
   tcp flags    =              0x11 .A...F
   proto        =               209 209
   (src)tos     =                 1
   (in)packets  =              8206
   (in)bytes    =                 0
   input        =              1728
   output       =             49409
   src as       =             50263
   dst as       =             20832


Flow Record:
   Flags        =              0x06 FLOW, Unsampled
   export sysid =                 2
   size         =                64
   first        =        1471447633 [2016-08-17 18:27:13]
   last         =        1472500355 [2016-08-29 22:52:35]
   msec_first   =               704
   msec_last    =               180
   src addr     =      188.6.252.10
   dst addr     =         1.187.0.0
   src port     =                 0
   dst port     =                 1
   fwd status   =                 0
   tcp flags    =              0x20 U.....
   proto        =                 0     0
   (src)tos     =                61
   (in)packets  =         184549376
   (in)bytes    =        1346374668
   input        =                 0
   output       =                 0
   src as       =              8209
   dst as       =              1608

I have not continued this, but it is obvious that something is not going 
right.

I can't tell why nfsen puts all this absurd data to the particular 
interface in the diagrams, but it's the first one defined in the 
profile, if that can tell you something.

Can someone please explain whether I'm doing something wrong (e.g. 
nfdump compilation, etc) or it's nfdump/nfsen bug?

What should I do to correct things?

Thanks in advance,
Nick


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