nfdump(1)

NAME
nfdump - netflow display and analyze program

SYNOPSIS

nfdump [options] [filter]

DESCRIPTION
nfdump is the netflow display and analyzing program of the nfdump tool set. It reads the netflow data from files stored by nfcapd and processes the flows according the options given. The filter syntax is comparable to tcpdump and extended for netflow data. Nfdump can also display many different top N flow and flow element statistics.

OPTIONS

-r inputfile
    Read input data from inputfile. Default is read from stdin.

-R expr
    Read input from a sequence of files in the same directory. expr may be one of:
    /any/dir Read recursively all files in directory dir.
    /dir/file Read all files beginning with file.
    /dir/file1:file2 Read all files from file1 to file2.
    When using in combination with a sub hierarchy:
    /dir/sub1/sub2/file1:sub3/sub4/file2
    Read all files from sub1/sub2/file1 sub3/sub4/file2 iterating over all required hierarchy levels.
    Note: files are read in alphabetical sequence.

-M expr
    Read input from multiple directories. expr looks like: /any/path/to/dir1:dir2:dir3 etc. and will be expanded to the directories: /any/path/to/dir1, /any/path/to/dir2 and /any/path/to/dir3 Any number of colon separated directories may be given. The files to read are specified by -r or -R and are expected to exist in all the given directories. The options -r and -R must not contain any directory part when used in conjunction with -M.

-m  Sort the netflow records according the date first seen. This option is usually only useful in conjunction with -M, when netflow records are read from different sources, which are not necessarily sorted.

-w outputfile
    If specified writes binary netflow records to outputfile ready to be processed again with nfdump. The default output is ASCII on stdout. In combination with options -m, -a, -b, and -B write aggregated and/or sorted flow cache in binary format to disk.

-f filterfile
    Reads the filter syntax from filterfile. Note: Any filter specified directly on the command line takes precedence over -f.

-t timewin
    Process only flows, which fall in the time window timewin, where timewin is YYYY/MM/dd.hh:mm:ss[-YYYY/MM/dd.hh:mm:ss]. Any parts of the time spec may be omitted e.g YYYY/MM/dd expands to YYYY/MM/dd.00:00:00-infinity and processes all flow from a given day onwards. The time window may also be specified as +/- n. In this case it is relativ to the beginning or end of all flows. +10 means the first 10 seconds of all flows, -10 means the last 10 seconds of all flows.

-c num
    Limit number of records to process to the first num flows.

-a  Aggregate netflow data. Automatically implies -a. Aggregation is done at connection level by taking the 5-tuple protocol, srcip, dstip, srcport and dstport.

-A aggregation
    Similar to Flexible Netflow (FNF), netflow records can be aggregated by any number of given v9 fields. aggregation is a ',' separated list of recognised tags of the following list:
    proto IP protocol
    srcip Source IP address
    dstip Destination IP address
    srcip4/net IPv4 source IP address with applied netmask
    srcip6/net IPv6 source IP address with applied netmask
    dstip4/net IPv4 destination IP address with applied netmask
    dstip6/net IPv6 destination IP address with applied netmask
    srcnet Apply netmask srcmask in netflow record for source IP
    dstnet Apply netmask dstmask in netflow record for dest IP
    srcport Source port
    dstport Destination port
    srcmask Source mask
    dstmask Destination mask
    srcvlan Source vlan label
    dstvlan Destination vlan label
    srcas Source AS number
    dstas Destination AS number
    inif SNMP input interface number
    outif SNMP output interface number
    next IP next hop
    bgpnext BGP next hop
    insrcmac In source MAC address
    outdstmac out destination MAC address
    indstmac In destintation MAC address
    outsrcmac Out source MAC address
    tos Source type of service
    srctos Source type of Service
    dsttos Destination type of Service
    mpls1 MPLS label 1
    mpls2 MPLS label 2
    mpls3 MPLS label 3
    mpls4 MPLS label 4
    mpls5 MPLS label 5
    mpls6 MPLS label 6
    mpls7 MPLS label 7
    mpls8 MPLS label 8
    mpls9 MPLS label 9
    mpls10 MPLS label 10

    nfdump automatically compiles an appropriate output format for the selected aggregation unless an explicit output format is given. The automatic output format is identical to -o 'fmt:%ts %td <fields> %pkt %byt %bps %bpp %fl' where <fields> represents the selected aggregation tags.

    Example:
        -A proto,srcip,dstport

        -A srcas,dstas

-b  Aggregate netflow records as bidirectional flows. Automatically implies -a. Aggregation is done on connection level by taking the 5-tuple protocol, srcip, dstip, srcport and dstport, or the reverse order for the corresponding connection flow. Input and output packets/bytes are counted and reported separate. Both flows are merged into a single record. An appropriate output format is selected automatically, which may be overwritten by any -o format option.

-B  Like -b but automagically swaps flows, such that src port is > 1024 and dst port is < 1024 as some exporters do not care sending the flows in proper order. It's considered to be a convenient option. If src and dst port are > 1024 or < 1024, the flows are taken as is.

-I  Print flow statistics from file specified by -r, or timeslot specified by -R/-M.

-D dns
    Set dns as nameserver to lookup hostnames.

-s statistic[:p][/orderby]
    Generate the Top N flow or flow element statistic. statistic can be:
    record Statistic about arregated netflow records.
    srcip Statistic about source IP addresses
    dstip Statistic about destination IP addresses
    ip Statistic about any (source or destination) IP addresses
    nhip Statistic about next hop IP addresses
    nhbip Statistic about BGP next hop IP addresses
    router Statistic about exporting router IP address
    srcport Statistic about source ports
    dstport Statistic about destination ports
    port Statistic about any (source or destination) ports
    tos Statistic about type of service - default src
    srctos Statistic about src type of service
    dsttos Statistic about dst type of service
    dir Statistic about flow directions ingress/egress
    srcas Statistic about source AS numbers
    dstas Statistic about destination AS numbers
    as Statistic about any (source or destination) AS numbers
    inif Statistic about input interface
    outif Statistic about output interface
    if Statistic about any interface
    srcmask Statistic about src mask
    dstmask Statistic about dst mask
    srcvlan Statistic about src vlan label
    dstvlan Statistic about dst vlan label
    vlan Statistic about any vlan label
    insrcmac Statistic about input src MAC address
    outdstmac Statistic about output dst MAC address
    indstmac Statistic about input dst MAC address
    outsrcmac Statistic about output src MAC address
    srcmac Statistic about any src MAC address
    dstmac Statistic about any dst MAC address
    inmac Statistic about any input MAC address
    outmac Statistic about any output MAC address
    mask Statistic about any mask
    proto Statistic about IP protocols
    mpls1 Statistic about MPLS label 1
    mpls2 Statistic about MPLS label 2
    mpls3 Statistic about MPLS label 3
    mpls4 Statistic about MPLS label 4
    mpls5 Statistic about MPLS label 5
    mpls6 Statistic about MPLS label 6
    mpls7 Statistic about MPLS label 7
    mpls8 Statistic about MPLS label 8
    mpls9 Statistic about MPLS label 9
    mpls10 Statistic about MPLS label 10

    By adding :p to the statistic name, the resulting statistic is split up into transport layer protocols. Default is transport protocol independent statistics.

    orderby is optional and specifies the order by which the statistics is ordered and can be flows, packets, bytes, pps, bps or bpp. You may specify more than one orderby which results in the same statistic but ordered differently. If no orderby is given, statistics are ordered by flows. You can specify as many -s flow element statistics on the command line for the same run.

    Example:
        -s srcip -s ip/flows -s dstport/pps/packets/bytes -s record/bytes

-O orderby
    Specifies the default orderby for flow element statistics -s, which applies when no orderby is given at -s. orderby can be flows, packets, bytes, pps, bps or bpp. Defaults to flows.

-l [+/-]packet_num
    Limit statistics output to those records above or below the packet_num limit. packet_num accepts positive or negative numbers followed by 'K' , 'M' or 'G' 10E3, 10E6 or 10E9 flows respectively. See also note at -L

-L [+/-]byte_num
    Limit statistics output to those records above or below the byte_num limit. byte_num accepts positive or negative numbers followed by 'K' , 'M' or 'G' 10E3, 10E6 or 10E9 bytes respectively. Note: These limits only apply to the statistics and aggregated outputs generated with -a -s or -S. To filter netflow records by packets and bytes, use the filter syntax 'packets' and 'bytes' described below.

-n num
    Define the number for the Top N statistics. Defaults to 10. If 0 is specified the number is unlimited.

-o format
    Selects the output format to print flows or flow record statistics (-s record). The following formats are available:
    raw Print each file flow record on multiple lines.
    line Print each flow on one line. Default format.
    long Print each flow on one line with more details
    biline Same as line, but for bidir flows
    bilong Same as long, but for bidir flows
    extended Print each flow on one line with even more details.
    csv Comma separated output for machine readable processing.
    pipe Legacy machine readable format: fields '|' separated.
    fmt:format User defined output format.
    For each defined output format except -o fmt:<format> an IPv6 long output format exists. line6, long6 and extended6. See output formats below for more information.

-q  Suppress the header line and the statistics at the bottom.

-N  Print plain numbers in output. Easier for post-parsing.

-i ident
    Change ident label in file, specified by -r to ident

-v file
    Verify file. Print data file version, number of blocks and compression status.

-x file
    Scan and print extension maps located in file file

-z  Compress flows. Use fast LZO1X-1 compression in output file.

-j file
    Compress/Uncompress a given file. If the file is compressed, uncompress it and vice versa.

-Z  Check filter syntax and exit. Sets the return value accordingly.

-X  Compiles the filer syntax and dumps the filter engine table to stdout. This is for debugging purpose only.

-V  Print nfdump version and exit.

-h  Print help text on stdout with all options and exit.

RETURN VALUE
Returns
    0 No error.
    255 Initialization failed.
    254 Error in filter syntax.
    250 Internal error.

OUTPUT FORMATS
The output format raw prints each flow record on multiple lines, including all information available in the record. This is the most detailed view on a flow.

Other output formats print each flow on a single line. Predefined output formats are line, long and extended The output format line is the default output format when no format is specified. It limits the imformation to the connection details as well as number of packets, bytes and flows.

The output format long is identical to the format line, and includes additional information such as TCP flags and Type of Service.

The output format extended is identical to the format long, and includes additional computed information such as pps, bps and bpp.

Fields:

    Date flow start: Start time flow first seen. ISO 8601 format including miliseconds.

    Duration: Duration of the flow in seconds and miliseconds. If flows are aggregated, duration is the time span over the entire periode of time from first seen to last seen.

    Proto: Protocol used in the connection.

    Src IP Addr:Port: Source IP address and source port.

    Dst IP Addr:Port: Destination IP address and destination port. In case of ICMP, port is decodes as type.code.

    Flags: TCP flags ORed of the connection.

    Tos: Type of service.

    Packets: The number of packets in this flow. If flows are aggregated, the packets are summed up.

    Bytes: The number of bytes in this flow. If flows are aggregated, the bytes are summed up.

    pps: The calculated packets per second: number of packets / duration. If flows are aggregated this results in the average pps during this periode of time.

    bps: The calculated bits per second: 8 * number of bytes / duration. If flows are aggregated this results in the average bps during this periode of time.

    Bpp: The calculated bytes per packet: number of bytes / number of packets. If flows are aggregated this results in the average bpp during this periode of time.

    Flows: Number of flows. If flows are listed only, this number is alwasy 1. If flows are aggregated, this shows the number of aggregated flows to one record.

Numbers larger than 1'000'000 (1000*1000), are scaled to 4 digits and one decimal digit including the scaling factor M, G or T for cleaner output, e.g. 923.4 M

To make the output more readable, IPv6 addresses are shrinked down to 16 characters. The seven most and seven least digits connected with two dots '..' are displayed in any normal output formats. To display the full IPv6 address, use the appropriate long format, which is the format name followed by a 6.

Example: -o line displays an IPv6 address as 2001:23..80:d01e where as the format -o line6 displays the IPv6 address in full length 2001:234:aabb::211:24ff:fe80:d01e. The combination of -o line -6 is equivalent to -o line6.

The output format fmt:<format> allows you to define your own output format. A format description format consists of a single line containing arbitrary strings and format specifier as described below

    %ts Start Time - first seen
    %te End Time - last seen
    %td Duration
    %pr Protocol
    %sa Source Address
    %da Destination Address
    %sap Source Address:Port
    %dap Destination Address:Port
    %sp Source Port
    %dp Destination Port
    %nh Next-hop IP Address
    %nhb BGP Next-hop IP Address
    %ra Router IP Address
    %sas Source AS
    %das Destination AS
    %in Input Interface num
    %out Output Interface num
    %pkt Packets - default input
    %ipkt Input Packets
    %opkt Output Packets
    %byt Bytes - default input
    %ibyt Input Bytes
    %obyt Output Bytes
    %fl Flows
    %flg TCP Flags
    %tos Tos - default src
    %stos Src Tos
    %dtos Dst Tos
    %dir Direction: ingress, egress
    %smk Src mask
    %dmk Dst mask
    %fwd Forwarding Status
    %svln Src vlan label
    %dvln Dst vlan label
    %ismc Input Src Mac Addr
    %odmc Output Dst Mac Addr
    %idmc Input Dst Mac Addr
    %osmc Output Src Mac Addr
    %mpls1 MPLS label 1
    %mpls2 MPLS label 2
    %mpls3 MPLS label 3
    %mpls4 MPLS label 4
    %mpls5 MPLS label 5
    %mpls6 MPLS label 6
    %mpls7 MPLS label 7
    %mpls8 MPLS label 8
    %mpls9 MPLS label 9
    %mpls10 MPLS label 10
    %eng Engine type/ID
    %bps bps - bits per second
    %pps pps - packets per second
    %bpp bps - Bytes per package

Example: the standard output format long can be created as
    -o "fmt:%ts %td %pr %sap -> %dap %flg %tos %pkt %byt %fl"

You may also define your own output format and have it compiled into nfdump. See nfdump.c section Output Formats for more details.

The csv output format is intended to be read by another program for further processing. As an example, see the parse_csv.pl Perl program. The cvs output format consists of one or more output blocks and one summary block. Each output block starts with a cvs index line followed by the cvs record lines. The index lines describes the order, how each following record is composed.

Example:
    Index line: ts,te,td,sa,da,sp,dp,pr,...
    Record line: 2004-07-11 10:30:00,2004-07-11 10:30:10,10.010,...

All records are in ASCII readable form. Numbers are not scaled, so each line can easly be parsed.

Indices used in nfdump 1.6:

    ts,te,td time records: t-start, t-end, duration
    sa,da src dst address sp,dp src, dst port
    pr protocol PF_INET or PF_INET6
    flg TCP Flags:
                   000001 FIN.
                   000010 SYN
                   000100 RESET
                   001000 PUSH
                   010000 ACK
                   100000 URGENT
                   e.g. 6 => SYN + RESET
    fwd forwarding status
    stos src tos
    ipkt,ibyt input packets/bytes
    opkt,obyt output packets, bytes
    in,out input/output interface SNMP number
    sas,das src, dst AS
    smk,dmk src, dst mask
    dtos dst tos
    dir direction
    nh,nhb nethop IP address, bgp next hop IP
    svln,dvln src, dst vlan id
    ismc,odmc input src, output dst MAC
    idmc,osmc input dst, output src MAC
    mpls1,mpls2 MPLS label 1-10
    mpls3,mpls4
    mpls5,mpls6
    mpls7,mpls8
    mpls9,mpls10
    ra router IP
    eng router engine type/id

See parse_csv.pl for more details.

FILTER
The filter syntax is similar to the well known pcap library used by tcpdump. The filter can be either specified on the command line after all options or in a separate file. It can span several lines. Anything after a '#' is treated as a comment and ignored to the end of the line. There is virtually no limit in the length of the filter expression. All keywords are case independent.

Any filter consists of one or more expressions expr. Any number of expr can be linked together:

expr and expr, expr or expr, not expr and ( expr ).

Expr can be one of the following filter primitives:

include
    @include <file>
    include the content of <file> into filter.

protocol version
    inet or ipv4 for IPv4
    inet6 or ipv6 for IPv6

protocol
    proto <protocol>
    where <protocol> can be any known protocol such as tcp, udp, icmp, icmp6, gre, esp, ah, etc. or a valid protocol number: 6, 17 etc.

IP address
    [SourceDestination] ip <ipaddr>
    [SourceDestination] host <ipaddr>
    with <ipaddr> as any valid IPv4, IPv6 address, or a full qualified hostname. In case of a hostname, the IP address is looked up in DNS. If more than a single IP address is found, all IP addresses are chained together. (ip1 or ip2 or ip3 ... ) The direction qualifier SourceDestination may be omitted.

    To check an IP address against a known IP list
    [SourceDestination] ip in [ <iplist> ]
    [SourceDestination] host in [ <iplist> ]
    <iplist> is a space separated list of individual <ipaddr> or full qualified hostnames, which are looked up in DNS. If more than a single IP address is found, all IP addresses are put into the list.

SourceDestination
    IP addresses, networks, ports, AS number etc. can be specifically selected by using a direction qualifier, such as src or dst. They can also be used in combination with and and or. such as src and dst ip ... Ommiting the SourceDestination qualifier is equivalent to src or dst.
    Example: src ip 192.168.1.1 and src and dst port 53

network
    [SourceDestination] net a.b.c.d m.n.r.s
    Select the IPv4 network a.b.c.d with netmask m.n.r.s.
    [SourceDestination] net <net>/<num>
    with <net> as a valid IPv4 or IPv6 network and <num> as maskbits. The number of mask bits must match the appropriate address familiy in IPv4 or IPv6. Networks may be abreviated such as 172.16/16 if they are unambiguous.

Port
    [SourceDestination] port [comp] <num>
    with <num> as any valid port number. If comp is omitted,
     '=' is assumed. comp is explained more detailed below.
    [SourceDestination] port in [ <portlist> ]
    A port can be compared against a know list, where <portlist> is a space separated list of individual port numbers.

ICMP
    icmp-type <num>
    icmp-code <num>
    with <num> as a valid icmp type/code. This automatically implies proto icmp.

Router ID
    engine-type <num>
    engine-id <num>
    with <num> as a valid router engine type/id (0..255).

Interface
    [inout] if <num>
    with num as the SNMP interface number. inout may be an optional selection of in or out. If ommited in or out applies.
    Example: in if 3

AS numbers
    [SourceDestination] as [comp] <num>
    with <num> as any valid as number. 32bit AS numbers are suported. If comp is omitted, '=' is assumed. comp is explained more detailed below.
    [SourceDestination] as in [ <ASlist> ]
    An AS number can be compared against a know list, where <ASlist> is a space separated list of individual AS numbers.

Prefix mask bits
    [SourceDestination] mask <bits>
    with <bits> as any valid prefix mask bit value.

Vlan labels
    [SourceDestination] vlan <num>
    with <num> as any valid vlan label.

Flags
    flags <tcpflags>
    with <tcpflags> as a combination of:
    A ACK.
    S SYN.
    F FIN.
    R Reset.
    P Push.
    U Urgent.
    X All flags on.
The ordering of the flags is not relevant. Flags not mentioned are treated as don't care. In order to get those flows with only the SYN flag set, use the syntax 'flags S and not flags AFRPU'.

Next hop IP
    next ip <ipaddr>
    with <ipaddr> as IPv4/IPv6 IP address of next hop router.

Next-hop router's IP in the BGP domain
    bgpnext ip <ipaddr>
    with <ipaddr> as IPv4/IPv6 next-hop router's IP in the BGP domain. ( v9 #18 )

Router IP
    router ip <ipaddr>
    Filter the flows according the IP address of the exporting router.

MAC addresses
    [InOutSrcDst] mac <addr>
    With <addr> any valid MAC address. mac can be more specific specified by using any combination of a direction specifier as defined by CISCO v9. in src, in dst, out src, out dst.

MPLS labels
    mpls label<n> [comp] <num>
    With <n> as any mpls label number 1..10. Filters exactly specified label<n>.
    mpls eos [comp] <num>
    Filters End of Stack label for a given value <num>.
    mpls exp<n> [comp] <bits>
    Filters experimental bits of label <n> with <bits> 0..7.

Packets
    packets [comp] <num> [scale]
    To filter for netflow records with a specific packet count.
    Example: packets > 1k

Bytes
    bytes [comp] <num> [scale]
    To filter for netflow records with a specific byte count.
    Example: bytes 46 filters all empty IPv4 packets

Aggregated flows
    flows [comp] <num> [scale]
    To filter for netflow records with a specific number of aggregated flows.

Type of Service (TOS)
    [SourceDestination] tos <num>
    With <num> 0..255. For compatibility with nfump 1.5.x: tos <num> is equivalent with src tos <num>

Packets per second: Calculated value.
    pps [comp] num [scale]
    To filter for flows with specific packets per second.

Duration: Calculated value
    duration [comp] num
    To filter for flows with specific duration in miliseconds.

Bits per second: Calculated value.
    bps [comp] num [scale]
    To filter for flows with specific bytes per second.

Bytes per packet: Calculated value.
    bpp [comp] num [scale]
    To filter for flows with specific bytes per packet.

scale scaling factor. Maybe k m g. Factor is 1000

comp The following comparators are supported:
    =, ==, >, <, EQ, LT, GT . If comp is omitted, '=' is assumed.

EXAMPLES
nfdump -r /and/dir/nfcapd.200407110845 -c 100 'proto tcp and ( src ip 172.16.17.18 or dst ip 172.16.17.19 )' Dumps the first 100 netflow records which match the given filter:

nfdump -R /and/dir/nfcapd.200407110845:nfcapd.200407110945 'host 192.168.1.2' Dumps all netflow records of host 192.168.1.2 from July 11 08:45 - 09:45

nfdump -M /to/and/dir1:dir2 -R nfcapd.200407110845:nfcapd.200407110945 -S -n 20 Generates the Top 20 statistics from 08:45 to 09:45 from 3 sources

nfdump -r /and/dir/nfcapd.200407110845 -S -n 20 -o extended Generates the Top 20 statistics, extended output format

nfdump -r /and/dir/nfcapd.200407110845 -S -n 20 'in if 5 and bps > 10k' Generates the Top 20 statistics from flows comming from interface 5

nfdump -r /and/dir/nfcapd.200407110845 'inet6 and proto tcp and ( src port > 1024 and dst port 80 ) Dumps all port 80 IPv6 connections to any web server.

NOTES
Generating the statistics for data files of a few hundred MB is no problem. However be careful if you want to create statistics of several GB of data. This may consume a lot of memory and can take a while. Also, anonymizing IP addresses is time consuming and uses a lot of CPU power, which reduces the number of flows per second. Therefore anonymizing takes place only, when flow records are printed or written to files. Any internal flow processing takes place using the original IP addresses.

SEE ALSO
nfcapd(1), nfprofile(1), nfreplay(1)

BUGS
There is still the famous last bug. Please report them - all the last bugs - back to me.