NTOP(8)                                                                NTOP(8)



NAME
       ntop - display top network users

SYNOPSIS
       ntop  [@filename] [-a|--access-log-file <path>] [-b|--disable-decoders]
       [-c|--sticky-hosts]    [-e|--max-table-rows]    [-f|--traffic-dump-file
       file>]   [-g|--track-local-hosts]  [-h|--help]  [-l|--pcap-log  <path>]
       [-m|--local-subnets <addresses>] [-n|--numeric-ip-addresses] [-p|--pro-
       tocols   <list>]   [-q|--create-suspicious-packets]  [-r|--refresh-time
       <number>]   [-s|--no-promiscuous]   [-t|--trace-level   <number>]   [-x
       <max_num_hash_entries>]  [-w|--http-server  <port>]  [-z|--disable-ses-
       sions]   [-A|--set-admin-password   password]   [-B|--filter-expression
       expression]  [-C  <configmode>]  [-D|--domain  <name>]  [-F|--flow-spec
       <specs>] [-M|--no-interface-merge] [-N|--wwn-map  <path>]  [-O|----out-
       put-packet-path  <path>]  [-P|--db-file-path  <path>] [-Q|--spool-file-
       path <path>] [-U|--mapper <URL>] [-V|--version]  [-X  <max_num_TCP_ses-
       sions>]    [--disable-instantsessionpurge]   [--disable-mutexextrainfo]
       [--disable-ndpi] [--disable-python] [--instance] [--p3p-cp] [--p3p-uri]
       [--skip-version-check] [--w3c] [-4|--ipv4] [-6|--ipv6]

       Unix options:

       [-d|--daemon]  [-i|--interface <name>] [-u|--user <user>] [-K|--enable-
       debug] [-L]  [--pcap_setnonblock]  [--use-syslog=  <facility>]  [--web-
       server-queue <number>]

       Windows option:

       [-i|--interface <number|name>]

       OpenSSL options:

       [-W|--https-server <port>] [--ssl-watchdog]


DESCRIPTION
       ntop  shows the current network usage. It displays a list of hosts that
       are currently using the network and reports information concerning  the
       (IP  and non-IP) traffic generated and received by each host.  ntop may
       operate as a front-end collector (sFlow and/or netFlow plugins) or as a
       stand-alone  collector/display  program.  A  web  browser  is needed to
       access the information captured by the ntop program.

       ntop is a hybrid layer 2 / layer 3 network monitor, that is by  default
       it  uses the layer 2 Media Access Control (MAC) addresses AND the layer
       3 tcp/ip addresses.  ntop is capable of associating the two, so that ip
       and non-ip traffic (e.g. arp, rarp) are combined for a complete picture
       of network activity.



COMMAND-LINE OPTIONS
       @filename
        The text of filename is copied -  ignoring  line  breaks  and  comment
        lines  (anything following a #) - into the command line.  ntop behaves
        as if all of the text had simply been typed directly  on  the  command
        line.   For example, if the command line is "-t 3 @d -u ntop" and file
        d contains just the line '-d', then the effective command line is -t 3
        -d  -u  ntop.   Multiple  @s are permitted. Nested @s (an @ inside the
        file) are not permitted.

        Remember, most ntop options are "sticky", that is  they  just  set  an
        internal  flag.  Invoking  them  multiple  times doesn't change ntop's
        behavior. However, options that set a value,  such  as  --trace-level,
        will  use  the  LAST value given: --trace-level 2 --trace-level 3 will
        run as --trace-level 3.

        Beginning with 3.1, many command-line options may also be set via  the
        web  browser  interface.  These changes take effect on the next run of
        and on each subsequent run until changed.



       -a | --access-log-file
        By default ntop does not maintain a log of HTTP requests to the inter-
        nal  web server.  Use this parameter to request logging and to specify
        the location of the file where these HTTP requests are logged.

        Each log entry is in Apache-like style.  The only  difference  between
        Apache and ntop logs is that an additional column has been added which
        has the time (in milliseconds) that ntop needed to serve the  request.
        Log entries look like this:

        192.168.1.1 - - [04/Sep/2003:20:38:55 -0500] - "GET / HTTP/1.1" 200 1489 4
        192.168.1.1 - - [04/Sep/2003:20:38:55 -0500] - "GET /index_top.html HTTP/1.1" 200 1854 4
        192.168.1.1 - - [04/Sep/2003:20:38:55 -0500] - "GET /index_inner.html HTTP/1.1" 200 1441 7
        192.168.1.1 - - [04/Sep/2003:20:38:56 -0500] - "GET /index_left.html HTTP/1.1" 200 1356 4
        192.168.1.1 - - [04/Sep/2003:20:38:56 -0500] - "GET /home_.html HTTP/1.1" 200 154/617 9
        192.168.1.1 - - [04/Sep/2003:20:38:56 -0500] - "GET /home.html HTTP/1.1" 200 1100/3195 10
        192.168.1.1 - - [04/Sep/2003:20:38:56 -0500] - "GET /About.html HTTP/1.1" 200 2010 10

        This  parameter is the complete file name of the access log.  In prior
        releases it was erroneously called --access-log-path.


       -b | --disable-decoders
        This parameter disables protocol decoders.

        Protocol decoders examine and collect information about layer 2 proto-
        cols  such as NetBIOS or Netware SAP, as well as about specific tcp/ip
        (layer 3) protocols, such as DNS, http and ftp.

        This support is specifically coded for each protocol and is  different
        from  the  capability  to count raw information (packets and bytes) by
        protocol specified by the -p | --protocols parameter, below.

        Decoding protocols is a significant consumer of resources. If the ntop
        host  is  underpowered or monitoring a very busy network, you may wish
        to disable protocol decoding via  this  parameter.   It  may  also  be
        appropriate  to  use this parameter if you believe that ntop has prob-
        lems handling some protocols that occur on your network.

        Even if decoding is disabled, ftp-data traffic  is  still  decoded  to
        look for passive ftp port commands.


       -c | --sticky-hosts
        Use  this  parameter to prevent idle hosts from being purged from mem-
        ory.

        By default idle hosts are periodically purged from  memory.   An  idle
        host is identified when no packets from or to that host have been mon-
        itored  for  the  period   of   time   defined   by   the   value   of
        PARM_HOST_PURGE_MINIMUM_IDLE in globals-defines.h.

        If  you use this option, all hosts - active and idle - are retained in
        memory for the duration of the ntop run.

        P2P users, port scans, popular web servers  and  other  activity  will
        cause ntop to record data about a large number of hosts.  On an active
        network, this will consume a significant - and always growing - amount
        of  memory.   It  is  strongly  recommended  that  you use a filtering
        expression to limit the hosts which are stored if  you  use  --sticky-
        hosts.

        The idle purge is a statistical one - a random selection of the eligi-
        ble hosts will be purged during each cycle.  Thus it is possible on  a
        busy  system  for an idle host to remain in the ntop tables and appear
        'active' for some considerable time after it is truly idle.


       -d | --daemon
        This parameter causes ntop to become a daemon, i.e. a task which  runs
        in  the  background without connection to a specific terminal.  To use
        ntop other than as a casual monitoring tool, you probably will want to
        use this option.

        WARNING:  If  you are running as a daemon, the messages from ntop will
        be 'printed' on to stdout and thus dropped.  You probably  don't  want
        to do this.  So remember to also use the -L or --use-syslog options to
        save the messages into the system log.


       -e | --max-table-rows
        This defines the maximum number of lines that  ntop  will  display  on
        each generated HTML page. If there are more lines to be displayed than
        this setting permits, only part of the data will be displayed.   There
        will  be page forward/back arrows placed at the bottom of the page for
        navigation between pages.


       -f | --traffic-dump-file
        By default, ntop captures traffic from network interface cards  (NICs)
        or from netFlow/sFlow probes.  However, ntop can also read data from a
        file - typically a tcpdump capture or the output from one of the  ntop
        packet capture options.

        if  you specify -f, ntop will not capture any traffic from NICs during
        or after the file has been read.  netFlow/sFlow capture - if enabled -
        would still be active.

        This option is mostly used for debug purposes.


       -g | --track-local-hosts
        By  default,  ntop tracks all hosts that it sees from packets captured
        on the various NICs.  Use this parameter to tell ntop to capture  data
        only  about  local  hosts.   Local  hosts  are  defined  based  on the
        addresses of the NICs and those networks identified as local  via  the
        -m | --local-subnets parameter.

        This  parameter  is  useful  on  large networks or those that see many
        hosts, (e.g. a border router  or  gateway),  where  information  about
        remote hosts is not desired/required to be tracked.


       -h | --help
        Print help information for ntop, including usage and parameters.


       -i | --interface
        Specifies  the  network interface or interfaces to be used by ntop for
        network monitoring.

        If multiple interfaces are used (this feature  is  available  only  if
        ntop  is  compiled  with thread support) their names must be separated
        with a comma. For instance -i "eth0,lo".

        If not specified, the default is the first Ethernet device, e.g. eth0.
        The specific device that is 'first' is highly system dependent.  Espe-
        cially on systems where the  device  name  reflects  the  driver  name
        instead of the type of interface.

        By  default,  traffic  information  obtained  by all the interfaces is
        merged together as if the traffic was seen by only one interface.  Use
        the -M parameter to keep traffic separate by interface.

        If you do not want ntop to monitor any interfaces, use -i none.

        Under  Windows, the parameter value is either the number of the inter-
        face or its name, e.g.   {6252C14C-44C9-49D9-BF59-B2DC18C7B811}.   Run
        ntop -h to see a list of interface name-number mappings (at the end of
        the help information).


       -l | --pcap-log
        This parameter causes a dump file to be created of the network traffic
        captured  by  ntop  in tcpdump (pcap) format.  This file is useful for
        debug, and may be read back into ntop by the -f |  --traffic-dump-file
        parameter.   The dump is made after processing any filter expression (
        never even sees filtered packets).

        The output file will  be  named  <path>/<log>.<device>.pcap  (Windows:
        <path>/<log>.pcap  ),  where  <path>  is defined by the -O | --output-
        packet-path parameter and <log> is defined by  this  -l  |  --pcap-log
        parameter.


       -m | --local-subnets
        ntop  determines  the ip addresses and netmasks for each active inter-
        face.  Any traffic on those networks is considered local.  This param-
        eter  allows  the  user  to define additional networks and subnetworks
        whose traffic is also considered local  in  ntop  reports.  All  other
        hosts are considered remote.

        Commas  separate multiple network values.  Both netmask and CIDR nota-
        tion   may   be   used,   even   mixed    together,    for    instance
        "131.114.21.0/24,10.0.0.0/255.0.0.0".

        The  local  subnet  - as defined by the interface address(es) - is/are
        always local and do not need to be specified.  If you do give the same
        value  as a NIC's local address, a harmless warning message is issued.


       -n | --numeric-ip-addresses
        By default, ntop resolves IP addresses using a combination  of  active
        (explicit)   DNS  queries  and  passive  sniffing.   Sniffing  of  DNS
        responses occurs when ntop receives a network  packet  containing  the
        response  to some other user's DNS query.  ntop captures this informa-
        tion and enters it into ntop's DNS cache, in  expectation  of  shortly
        seeing  traffic  addressed  to  that host. This way ntop significantly
        reduces the number of DNS queries it makes.

        This parameter causes  ntop  to  skip  DNS  resolution,  showing  only
        numeric  IP  addresses instead of the symbolic names.  This option can
        useful when the DNS is not present or quite slow.


       -p | --protocols
        This parameter is used to specify the TCP/UDP protocols that ntop will
        monitor.  The  format  is <label>=<protocol list> [, <label>=<protocol
        list>], where label is used to  symbolically  identify  the  <protocol
        list>. The format of <protocol list> is <protocol>[|<protocol>], where
        <protocol> is either a valid protocol specified inside  the  /etc/ser-
        vices file or a numeric port range (e.g. 80, or 6000-6500).

        A simple example is --protocols="HTTP=http|www|https|3128,FTP=ftp|ftp-
        data", which reduces the protocols displayed  on  the  "IP"  pages  to
        three:

        Host                      Domain Data          HTTP   FTP   Other IP
        ns2.attbi.com             <flag>  954 63.9 %      0     0        954
        64.124.83.112.akamai.com  <flag>  240 16.1 %    240     0          0
        64.124.83.99.akamai.com   <flag>  240 16.1 %    240     0          0
        toolbarqueries.google.com <flag>   60 4.0 %      60     0          0

        If  the  <protocol  list> is very long you may store it in a file (for
        instance protocol.list).  To do so, specify the file name  instead  of
        the <protocol list> on the command line.  e.g.  ntop -p protocol.list

        If the -p parameter is omitted the following default value is used:

          FTP=ftp|ftp-data
          HTTP=http|www|https|3128     3128 is Squid, the HTTP cache
          DNS=name|domain
          Telnet=telnet|login
          NBios-IP=netbios-ns|netbios-dgm|netbios-ssn
          Mail=pop-2|pop-3|pop3|kpop|smtp|imap|imap2
          DHCP-BOOTP=67-68
          SNMP=snmp|snmp-trap
          NNTP=nntp
          NFS=mount|pcnfs|bwnfs|nfsd|nfsd-status
          X11=6000-6010
          SSH=22

          Peer-to-Peer Protocols
          ----------------------
          Gnutella=6346|6347|6348
          Kazaa=1214
          WinMX=6699|7730
          DirectConnect=0      Dummy port as this is a pure P2P protocol
          eDonkey=4661-4665

          Instant Messenger
          -----------------
          Messenger=1863|5000|5001|5190-5193

        NOTE:  To  resolve protocol names to port numbers, they must be speci-
        fied in the system file used to  list  tcp/udp  protocols  and  ports,
        which  is  typically  /etc/services  file.  You will have to match the
        names in that file, exactly.  Missing  or  unspecified  (non-standard)
        ports must be specified by number, such as 3128 in our examples above.

        If you have a file named /etc/protocols, don't get confused by it,  as
        that's  the Ethernet protocol numbers, which are not what you're look-
        ing for.


       -q | --create-suspicious-packets
        This parameter tells ntop to create a dump file of suspicious packets.

        There  are  many,  many,  things  that cause a packet to be labeled as
        'suspicious', including:

          Detected ICMP fragment
          Detected Land Attack against host
          Detected overlapping/tiny packet fragment
          Detected traffic on a diagnostic port
          Host performed ACK/FIN/NULL scan
          Host rejected TCP session
          HTTP/FTP/SMTP/SSH detected at wrong port
          Malformed TCP/UDP/ICMP packet (packet too short)
          Packet # %u too long
          Received a ICMP protocol Unreachable from host
          Sent ICMP Administratively Prohibited packet to host
          Smurf packet detected for host
          TCP connection with no data exchanged
          TCP session reset without completing 3-way handshake
          Two MAC addresses found for the same IP address
          UDP data to a closed port
          Unknown protocol (no HTTP/FTP/SMTP/SSH) detected (on port 80/21/25/22)
          Unusual ICMP options

        When this parameter is used, one file  is  created  for  each  network
        interface  where  suspicious packets are found. The file is in tcpdump
        (pcap) format and is named  <path>/ntop-suspicious-pkts.<device>.pcap,
        where <path> is defined by the -O | --output-packet-path parameter.


       -r | --refresh-time
        Specifies  the delay (in seconds) between automatic screen updates for
        those generated HTML pages which support them.  This parameter  allows
        you  to  leave  your browser window open and have it always displaying
        nearly real-time data from ntop.

        The default is 3 seconds.  Please note that if the delay is very short
        (1  second for instance), ntop might not be able to process all of the
        network traffic.


       -s | --no-promiscuous
        Use this parameter to  prevent  from  setting  the  interface(s)  into
        promiscuous mode.

        An  interface  in  promiscuous  mode  will accept ALL Ethernet frames,
        regardless of whether they directed (addressed) to the  specific  net-
        work  interface  (NIC)  or not.  This is an essential part of enabling
        ntop to monitor an entire network.  (Without  promiscuous  mode,  ntop
        will  only see traffic directed to the specific host it is running on,
        plus broadcast traffic such as the arp and dhcp protocols.

        Even if you use this parameter, the interface could well be in promis-
        cuous mode if another application enabled it.

        ntop  passes  this  setting on to libpcap, the packet capture library.
        On many systems, a non-promiscuous open of the network interface  will
        fail, since the libpcap function on most systems require it to capture
        raw packets ( ntop captures raw packets so that we may view  and  ana-
        lyze the layer 2 - MAC - information).

        Thus on most systems, ntop must probably still be started as root, and
        this option is largely ornamental.   If  it  fails,  you  will  see  a
        ***FATALERROR***  message  referring  to  pcap_open_live() and then an
        information message, "Sorry, but on this  system,  even  with  -s,  it
        appears that ntop must be started as root".


       -t | --trace-level
        This  parameter specifies the 'information' level of messages that you
        wish ntop to display (on stdout or to the log).  The higher the  trace
        level  number the more information that is displayed.  The trace level
        ranges between 0 (no trace) and 5 (full debug tracings).

        The default trace value is 3.

        Trace level 0 is not quite zero messages.  Fatal  errors  and  certain
        startup/shutdown messages are always displayed.  Trace level 1 is used
        to display errors only, level 2 for  both  errors  and  warnings,  and
        level 3 displays error, warning and informational messages.

        Trace  level  4 is called 'noisy' and it is - generating many messages
        about the internal functioning of ntop.  Trace level 5 and  above  are
        'noisy'  plus extra logs, i.e. all possible messages, with a file:line
        tag prepended to every message.


       -u | --user
        Specifies the user ntop should run as after it initializes.

        ntop must normally be started as root so that it has sufficient privi-
        leges  to  open  the  network  interfaces  in  promiscuous mode and to
        receive raw frames.  See  the  discussion  of  -s  |  --no-promiscuous
        above, if you wish to try starting ntop as a non-root user.

        Shortly  after  starting  up,  ntop becomes the user you specify here,
        which normally has substantially reduced privileges, such as no  login
        shell.   This  is  the  userid  which  owns ntop's database and output
        files.

        The value specified may be either a username or  a  numeric  user  id.
        The group id used will be the primary group of the user specified.

        If  this  parameter is not specified, ntop will try to switch first to
        'nobody' and then to 'anonymous' before giving up.

        NOTE: This should not be root unless you really understand  the  secu-
        rity  risks. In order to prevent this by accident, the only way to run
        ntop as root is to explicitly specify -u root.  Don't do it.


       -x

       -X
        ntop creates a new hash/list entry for each new host/TCP session seen.
        In  case of DOS (Denial Of Service) an attacker can easily exhaust all
        the host available memory because ntop is creating entries  for  dummy
        hosts.  In  order to avoid this you can set an upper limit in order to
        limit the memory ntop can use.


       -w | --http-server

       -W | --https-server
        ntop offers an embedded web server to present the information that has
        been  so  painstakingly  gathered.   An  external  HTTP  server is NOT
        required NOR supported.  The ntop web  server  is  embedded  into  the
        application.   These  parameters  specify the port (and optionally the
        address (i.e. interface)) of the ntop web server.

        For example, if started with -w 3000 (the default port),  the  URL  to
        access ntop is http://hostname:3000/.  If started with a full specifi-
        cation,  e.g.  -w  192.168.1.1:3000,  ntop  listens   on   only   that
        address/port combination.

        If  -w  is set to 0 the web server will not listen for http:// connec-
        tions.

        -W operates similarly, but controls the port for the https://  connec-
        tions.

        Some examples:

        ntop  -w 3000 -W 0 (this is the default setting) HTTP requests on port
        3000 and no HTTPS.

        ntop -w 80 -W 443 Both HTTP and HTTPS have been enabled on their  most
        common ports.

        ntop -w 0 -W 443 HTTP disabled, HTTPS enabled on the common port.

        Certain sensitive, configuration pages of the ntop web server are pro-
        tected by a userid/password.   By  default,  these  are  the  user/URL
        administration,  filter,  shutdown  and  reset stats are password pro-
        tected
         and are accessible initially only to user admin with a  password  set
        during the first run of ntop.

        Users  can  modify/add/delete  users/URLs  using ntop itself - see the
        Admin tab.

        The passwords, userids and URLs to protect with passwords  are  stored
        in  a database file.  Passwords are stored in an encrypted form in the
        database for further security.  Best practices call for securing  that
        database so that only the ntop user can read it.

        There  is  a  discussion  in  docs/FAQ about further securing the ntop
        environment.


       -z | --disable-sessions
        This parameter disables TCP session tracking.  Use it for better  per-
        formance or when you don't really need/care to track sessions.


       -A | --set-admin-password
        This  parameter  is  used  to  start ntop , set the admin password and
        quit. It is quite useful for installers that need to automatically set
        the password for the admin user.

        -A and --set-admin-password (without a value) will prompt the user for
        the password.

        You may also use this parameter to set a specific value  using  --set-
        admin-password=value.   The = is REQUIRED and no spaces are permitted!

        If you attempt to run ntop as a daemon without setting a  password,  a
        FATAL ERROR message is generated and ntop stops.


       -B | --filter-expression
        Filters  allows  the user to restrict the traffic seen by ntop on just
        about any imaginable item.

        The filter expression is set at run time by this parameter, but it may
        be  changed during the ntop run on the Admin | Change Filter web page.

        The basic format is -B filter , where the quotes are REQUIRED

        The syntax of the filter expression uses the same BPF (Berkeley Packet
        Filter) expressions used by other packages such as tcpdump

        For  instance,  suppose  you are interested only in the traffic gener-
        ated/received by the host jake.unipi.it.  ntop  can  then  be  started
        with the following filter:

        ntop -B src host jake.unipi.it or dst host jake.unipi.it

        or in shorthand:

        ntop -B host jake.unipi.it or host jake.unipi.it

        See  the 'expression' section of the tcpdump man page - usually avail-
        able at http://www.tcpdump.org/tcpdump_man.html - for further informa-
        tion and the best quick guide to BPF filters currently available.

        WARNING: If you are using complex filter expressions, especially those
        with =s or meaningful spaces in them, be sure and use the long  option
        format, --filter-expression="xxxx" and not -B "xxxx".



       -C |
        This  instruments ntop to be used in two configurations: host and net-
        work mode. In  host  mode  (default)  ntop  works  as  usual:  the  IP
        addresses  received  are  those  of  real  hosts.  In host mode the IP
        addresses received are those of  the  C-class  network  to  which  the
        address  belongs.  Using ntop in network mode is extremely useful when
        installed in a traffic exchange (e.g. in the middle of  the  Internet)
        whereas  the  host  mode  should be used when ntop is installed on the
        edge of a network (e.g. inside a company). The network  mode  signifi-
        cantly reduces the amount of work ntop has to perform and it has to be
        used whenever ntop is used to find out how the network  traffic  flows
        and not to pin-point specific hosts.



       -D | --domain
        This  identifies  the  local  domain suffix, e.g. ntop.org.  It may be
        necessary, if ntop is having difficulty determining it from the inter-
        face.


       -F | --flow-spec
        It  is used to specify network flows similar to more powerful applica-
        tions such as NeTraMet.  A flow is a stream of captured  packets  that
        match a specified rule. The format is

        <flow-label>='<matching  expression>'[,<flow-label>='<matching expres-
        sion>']

        , where the label is used to symbolically identify the flow  specified
        by  the  expression.  The expression is a bpf (Berkeley Packet Filter)
        expression. If an expression is specified, then the  information  con-
        cerning flows can be accessed following the HTML link named 'List Net-
        Flows'.

        For instance define two flows  with  the  following  expression  Luca-
        Hosts='host  jake.unipi.it  or host pisanino.unipi.it',GatewayRoutedP-
        kts='gateway gateway.unipi.it' .

        All   the   traffic   sent/received   by   hosts   jake.unipi.it    or
        pisanino.unipi.it  is  collected  by  ntop  and added to the LucaHosts
        flow, whereas all the packet routed by  the  gateway  gateway.unipi.it
        are  added  to  the  GatewayRoutedPkts flow. If the flows list is very
        long you may store in a file (for instance flows.list) and specify the
        file name instead of the actual flows list (in the above example, this
        would be 'ntop -F flows.list').

        Note that the double quotations around the entire flow expression  are
        required.


       -K | --enable-debug
        Use  this  parameter  to  simplify  application  debug.  It does three
        things: 1. Does not fork() on the "read only" html pages.  2. Displays
        mutex  values on the configuration (info.html) page.  3. (If available
        - glibc/gcc) Activates an automated backtrace on application errors.


       -L | --use-syslog=facility
        Use this parameter to send log messages to the system log  instead  of
        stdout.

        -L  and  the  simple  form  --use-syslog use the default log facility,
        defined as LOG_DAEMON in the #define symbol DEFAULT_SYSLOG_FACILITY in
        globals-defines.h.

        The  complex  form, --use-syslog=facility will set the log facility to
        whatever value (e.g. local3, security) you specify.  The = is REQUIRED
        and no spaces are allowed!

        This  setting  applies  both  to  ntop  and  to any child fork()ed for
        reporting.  If this parameter is not  specified,  any  fork()ed  child
        will  use  the  default value and will log it's messages to the system
        log (this occurs because the fork()ed child must give up  it's  access
        to the parents stdout).

        Because  various  systems do not make the permissible names available,
        we have a table at the end of globals-core.c.   Look  for  myFacility-
        Names.


       -M | --no-interface-merge
        By  default, ntop merges the data collected from all of the interfaces
        (NICs) it is monitoring into a single set of counters.

        If you have a simple network, say a small LAN with a connection to the
        internet, merging data is good as it gives you a better picture of the
        whole network.  For larger, more complex networks,  this  may  not  be
        desirable.   You  may  also  have other reasons for wishing to monitor
        each interface separately, for example DMZ vs. LAN traffic.

        This option instructs ntop not to merge network  interfaces  together.
        This  means  that  ntop will collect statistics for each interface and
        report them separately.

        Only ONE interface may be reported on at a time  -  use  the  Admin  |
        Switch  NIC  option  on  the  web  server to select which interface to
        report upon.

        Note that activating either the  netFlow  and/or  sFlow  plugins  will
        force the setting of -M.  Once enabled, you cannot go back.


       -N | --wwn-map
        This options names the file providing the map of WWN to FCID/VSAN ids.


       -O | --output-packet-path
        This  parameter  defines  the  base  path  for  the   ntop-suspicious-
        pkts.XXX.pcap and normal packet dump files.

        If  this parameter is not specified, the default value is the config.h
        parameter CFG_DBFILE_DIR, which is set  during  ./configure  from  the
        --localstatedir=  parameter.   If --localstatedir is not specified, it
        defaults to the --prefix value plus /var (e.g. /usr/local/var).

        Be aware that this may not be what you expect when running ntop  as  a
        daemon or Windows service. Setting an explicit and absolute path value
        is STRONGLY recommended if you use this facility.


       -P | --db-file-path

       -Q | --spool-file-path
        These parameters specify where ntop stores database files.

        There are two types, 'temporary' - that is  ones  which  need  not  be
        retained  from  ntop  run  to ntop run, and 'permanent', which must be
        retained (or recreated).

        The 'permanent' databases are the preferences, "prefsCache.db" and the
        password  file, "ntop_pw.db".  These are stored in the -P | --db-file-
        path specified location.

        Certain plugins use the -P |  --db-file-path  specified  location  for
        their  database  ("LsWatch.db")  or  (as  a  default  value) for files
        (.../rrd/...).

        The 'temporary' databases are the  address  queue,  "addressQueue.db",
        the  cached  DNS resolutions, "dnsCache.db" and the MAC prefix (vendor
        table), "macPrefix.db".

        If only -P | --db-file-path is specified, it is used for both types of
        databases.

        The  directories  named must allow read/write and file creation by the
        ntop user.  For security, nobody else should have even read access  to
        these files.

        Note  that the default value is the config.h parameter CFG_DBFILE_DIR.
        This is set during ./configure from  the  --localstatedir=  parameter.
        If --localstatedir is not specified, it defaults to the --prefix value
        plus /var (e.g. /usr/local/var).

        This may not be what you expect when running ntop as a daemon or  Win-
        dows service.

        Note that on versions of ntop prior to 2.3, these parameters defaulted
        to "." (the current working directory, e.g.  the value returned by the
        pwd  command)  and  caused havoc as it was different when ntop was run
        from the command line, vs. run via cron, vs. run from  an  initializa-
        tion script.

        Setting an explicit and absolute path value is STRONGLY recommended.


       -U | --mapper
        Specifies the URL of the mapper.pl utility.

        If  provided,  ntop  creates  a clickable hyperlink on the 'Info about
        host xxxxxx' page to this URL by appending ?host=xxxxx.  Any  type  of
        host  lookup  could  be  performed, but this is intended to lookup the
        geographical location of the host.

        A cgi-based mapper interface to http://www.multimap.com is part of the
        ntop distribution [see www/Perl/mapper.pl]).


       -V | --version
        Prints ntop version information and then exits.


       -W | --https-server
        (See the joint documentation with the -w parameter, above)


       --disable-instantsessionpurge
        ntop sets completed sessions as 'timed out' and then purge them almost
        instantly, which is not the behavior you might expect from the discus-
        sions  about purge timeouts.  This switch makes ntop respect the time-
        outs for completed sessions.  It is NOT the default because a busy web
        server  may  have  100s  or 1000s of completed sessions and this would
        significantly increase the amount of memory ntop uses.


       --disable-mutexextrainfo
        ntop stores extra information about the locks and unlocks of the  pro-
        tective  mutexes  it  uses. Since ntop uses fine-grained locking, this
        information is updated frequently.  On some  OSes,  the  system  calls
        used  to  collect  this  informatio  (getpid() and gettimeofday()) are
        expensive.  This option disables the  extra  information.   It  should
        have no processing impact on ntop
         -  however  should ntop actually deadlock, we would lose the informa-
        tion that sometimes tells us why.


       --disable-ndpi
        ntop is started without nDPI support thus  application  protocols  are
        not recognized.


       --disable-python
        ntop  is  started  without the Python interpreter. Beware as some ntop
        reports are based on python,  thus  disabling  it  will  prevent  some
        reports to work properly.


       --instance

        You  can  run  multiple instances of ntop simultaneously by specifying
        different -P values (typically through separate ntop.conf files).   If
        you  set  a  value  for  this parameter (available only on the command
        line), you (1) display the 'instance' name on every web page  and  (2)
        alter the log prefix from "NTOP" to your chosen value.

        If  you want to make the tag more obvious, create a .instance class in
        style.css, e.g.:

           .instance {
             color: #666666;
             font-size: 18pt;
           }

        Note (UNIX): To run completely different versions of the ntop  binary,
        you need to compile and install into a different library (using ./con-
        figure --prefix) and then specify the LD_LIBRARY_PATH before invoking,
        e.g.

        LD_LIBRARY_PATH=/devel/lib/ntop/:... /devel/bin/ntop ...args...

        If  present,  a file of the form <instance>_ntop_logo.gif will be used
        instead of the normal ntop_logo.gif.  This is tested for ONLY once, at
        the  beginning  of  the run.  The EXACT word(s) of the --instance flag
        are used, without testing if they make a proper file name.  If  -  for
        any reason - the file is not found, an informational message is logged
        and the normal logo file is used.  To construct your own logo, make it
        a 300x40 transparent gif.

        NOTE: On the web pages, ntop uses the dladdr() function.  The original
        Solaris routine had a bug, replicated in FreeBSD (and  possibly  other
        places)  where  it uses the ARGV[0] value - which might be erroneous -
        instead of the actual file name.  If the 'running  from'  value  looks
        bogus but the 'libaries in' value looks ok, go with the libarary.


       --p3p-cp

       --p3p-uri

        P3P is a W3C recommendation - http://www.w3.org/TR/P3P/ - for specify-
        ing personal information a site collects and what  it  does  with  the
        information.  These parameters allow to return P3P information.  We do
        not supply samples.


       --pcap_setnonblock
        On some platforms, the ntop web server will hang or appear to hang (it
        actually  just  responds incredibly slowly to the first request from a
        browser session), while the rest of ntop runs just fine. This is known
        to be an issue under FreeBSD 4.x.

        This  option  sets the non-blocking option (assuming it's available in
        the version of libpcap that is installed).

        While this works around the problem  (by  turing  an  interupt  driven
        process into a poll), it also MAY signifcantly increases the cpu usage
        of ntop.  Although it does not actually  interfere  with  other  work,
        seeing  ntop use 80-90% or more of the cpu is not uncommon - don't say
        we didn't warn you.

        THIS OPTION IS OFFICIALLY UNSUPPORTED and used at your own risk.  Read
        the docs/FAQ write-up.


       --skip-version-check
        By  default,  ntop accesses a remote file to periodically check if the
        most current version is running.  This  option  disables  that  check.
        Please  review  the privacy notice at the bottom of this page for more
        information.  By default, the recheck period is slightly more than  15
        days.   This  can be adjusted via a constant in globals-defines.h.  If
        the result of the initial check indicates that the ntop version  is  a
        'new  development'  version  (that  is newer than the latest published
        development version), the recheck is disabled.  This is because  which
        fixes and enhancements were present/absent from the code.

        NOTE: At present, the recheck does not work under Windows.


       --ssl-watchdog

        Enable  a watchdog for webserver hangs. These usually happen when con-
        necting with older browsers. The user  gets  nothing  back  and  other
        users can't connect. Internally, packet processing continues but there
        is no way to access the data through the web server or  shutdown  ntop
        cleanly.   With  the  watchdog,  a timeout occurs after 3 seconds, and
        processing continues with a log message. Unfortunately, the user  sees
        nothing - it just looks like a failed connection. (also available as a
        ./configure option, --enable-sslwatchdog)


       --w3c
        By default, ntop generates displayable but not great html.  There  are
        a  number  of tags we do not generate because they cause problems with
        older browsers which are still commonly used or are important to  look
        good  on  real-world browsers.  This flag tells ntop to generate 'BET-
        TER' (but not perfect) w3c compliant html 4.01 output. This in no  way
        addresses  all  of the compatibility and markup issues.  Over time, we
        would like to make ntop more compatible, but it will  never  be  100%.
        If you find any issues, please report them to ntop-dev.


       -4 | --ipv4
        Use IPv4 connections.


       -6 | --ipv6
        Use IPv6 connections


WEB VIEWS
       While  ntop  is running, multiple users can access the traffic informa-
       tion using their web browsers.  ntop does not generate 'fancy' or 'com-
       plex'  html,  although  it does use frames, shallowly nested tables and
       makes some use of JavaScript and Cascading Style Sheets.

       Beginning with release 3.1,  the  menus  are  cascading  dropdowns  via
       JSCookMenu.  With release 3.2, this extends to plugins.

       We do not expect problems with any current web browser, but our ability
       to test with less common ones is very limited.   Testing  has  included
       Firefox  and Internet Explorer, with very limited testing on other cur-
       rent common browsers such as Opera.

       In documentation and this man page, when we refer to  a  page  such  as
       Admin | Switch NIC, we mean the Broad category "Admin" and the detailed
       item "Switch NIC" on that Admin menu.


NOTES
       ntop requires a number of external  tools  and  libraries  to  operate.
       Certain  other  tools  are optional, but add to the program's capabili-
       ties.


       --webserver-queue
        Specifies the maximum number of web server  requests  for  the  tcp/ip
        stack  to  retain  in  it's  queue  awaiting  delivery to the ntop web
        server.  Requests in excess of this queue may be dropped (allowing for
        retransmission)  or rejected at the tcp/ip stack level, depending upon
        the OS.  Whatever happens, happens at the OS level, without any infor-
        mation being delivered to ntop

        Required libraries include:

        libpcap from http://www.tcpdump.org/, version 0.7.2 or newer. 0.8.3 or
        newer is strongly recommended.

        The Windows version makes use of WinPcap (libpcap for  Windows)  which
        may be downloaded from http://winpcap.polito.it/install/default.htm.

        WARNING: The 2.x releases of WinPcap will NOT support SMP machines.

        gdbm from http://www.gnu.org/software/gdbm/gdbm.html

        ntop  requires  a  POSIX  threads library. As of ntop 3.2, the single-
        threaded version of ntop is no longer available.

        The gd 2.x library, for  the  creation  of  png  files,  available  at
        http://www.boutell.com/gd/.

        The  libpng 1.2.x library, for the creation of png files, available at
        http://www.libpng.org/pub/png/libpng.html.

        ntop should support both gd 1.X and libpng 1.0.x  libraries  but  this
        has  not  been  tested.   Note that there are incompatibilities if you
        compile with one version of these libraries  and  then  run  with  the
        other.   Please  read  the discussion in docs/FAQ before reporting ANY
        problems of this nature.

        (if an https:// server is desired) openSSL from  the  OpenSSL  project
        available at http://www.openssl.org.

        The  rrdtool  library  is required by the rrd plugin.  rrdtool creates
        'Round-Robin databases' which are used to store and  graph  historical
        data  in a format that permits long duration retention without growing
        larger  over   time.    The   rrdtool   home   page   is   http://peo-
        ple.ee.ethz.ch/~oetiker/webtools/rrdtool/

        ntop includes a limited version of rrdtool 1.0.49 in the myrrd/ direc-
        tory.  Users of ntop 3.2 should not need to specifically install  rrd-
        tool.

        The  sflow  Plugin  is courtesy of and supported by InMon Corporation,
        http://www.inmon.com/sflowTools.htm.

        There are other optional libraries.  See the output of ./configure for
        a fuller listing.

        Tool  locations  are  current as of August 2005 - please send email to
        report new locations or dead links.


SEE ALSO
       top(1), tcpdump(8).  pcap(3).


PRIVACY NOTICE
       By default at startup and at periodic intervals, the ntop program  will
       retrieve  a  file  containing current ntop program version information.
       Retrieving this file allows this ntop instance to confirm  that  it  is
       running the most current version.

       The  retrieval is done using standard http:// requests, which will cre-
       ate log records on the hosting system.  These log  records  do  contain
       information  which  identifies  a specific ntop site.  Accordingly, you
       are being notified that this individually identifiable  information  is
       being transmitted and recorded.

       You  may  request - via the --skip-version-check run-time option - that
       this check be eliminated.  If you  use  this  option,  no  individually
       identifiable information is transmitted or recorded, because the entire
       retrieval and check is skipped.

       We ask you to allow this retrieval and check, because it benefits  both
       you and the ntop developers.  It benefits you because you will be auto-
       matically notified if the ntop program  version  is  obsolete,  becomes
       unsupported  or  is  no  longer current.  It benefits the developers of
       ntop because it allows us  to  determine  the  number  of  active  ntop
       instances,  and  the  operating  system/versions that users are running
       ntop under.  This allows us to focus development resources  on  systems
       like those our users are using ntop on.

       The  individually  identifiable  information  is  contained  in the web
       server log records which are automatically created each time  the  ver-
       sion  file  is retrieved.  This is a function of the web server and not
       of ntop , but we do take advantage of it.  The log record shows the  IP
       address  of  the  requestor (the ntop instance) and a User-Agent header
       field.  We place information in the User-Agent header as follows:

           ntop/<version>
           host/<name from config.guess>
           distro/<if one>
           release/<of the distro, also if one>
           kernrlse/<kernel version or release>
           GCC/<version>
           config() <condensed parameters from ./configure>
           run()    <condensed flags - no data - from the execution line>
           libpcap/<version>
           gdbm/<version>
           openssl/<version>
           zlib/<version>
           access/<http, https, both or none>
           interfaces() <given interface names>

       For example:

           ntop/2.2.98 host/i686-pc-linux-gnu  distro/redhat  release/9  kern-
       rlse/2.4.20-8smp
           GCC/3.2.2  config(i18n) run(i; u; P; w; t; logextra; m; instantses-
       sionpurge;
           schedyield; d; usesyslog=; t) gdbm/1.8.0 openssl/0.9.7a zlib/1.1.4
           access/http interfaces(eth0,eth1)

       Distro and release information is determined at compile time  and  con-
       sists  of  information typically found in the /etc/release (or similar)
       file. See the ntop tool linuxrelease for how this is determined.

       gcc compiler version (if available) is the internal version #s for  the
       gcc compiler, e.g. 3.2.3.

       kernrlse  is  the  Linux  Kernel  version or the xBSD 'release' such as
       4.9-RELEASE and is determined from the uname data (if it's  available).

       The ./configure parameters are stripped of directory paths, leading -s,
       etc. to create a short form that shows us what  ./configure  parameters
       people are using.

       Similarly, the run time parameters are stripped of data and paths, just
       showing which flags are being used.

       The libpcap, gdbm, openssl and zlib  versions  come  from  the  strings
       returned by the various inquiry functions (if they're availabe).

       Here's a sample log record:

       67.xxx.xxx.xxx  -  -  [28/Dec/2003:12:11:46  -0500]  "GET  /version.xml
       HTTP/1.0"
         200 1568 www.burtonstrauss.com "-"  "ntop/2.2.98  host/i686-pc-linux-
       gnu
         distro/redhat release/9 kernrlse/2.4.20-8smp GCC/3.2.2 config(i18n)
         run(i; u; P; w; t; logextra; m; instantsessionpurge; schedyield; d;
         usesyslog=)    libpcap/0.8   gdbm/1.8.0   openssl/0.9.7a   zlib/1.1.4
       access/http
         interfaces(eth0,eth1,eth2)" "-"


USER SUPPORT
       Please send bug reports to  the  ntop-dev  <ntop-dev@ntop.org>  mailing
       list. The ntop <ntop@ntop.org> mailing list is used for discussing ntop
       usage issues. In order to post messages on the lists a (free) subscrip-
       tion  is required to limit/avoid spam. Please do NOT contact the author
       directly unless this is a personal question.

       Commercial support is available upon request. Please see the ntop  site
       for further info.

       Please send code patches to <patch@ntop.org>.


AUTHOR
       ntop's  author  is Luca Deri (http://luca.ntop.org/) who can be reached
       at <deri@ntop.org>.


LICENCE
       ntop is distributed under the GNU GPL licence (http://www.gnu.org/).


ACKNOWLEDGMENTS
       The author acknowledges the Centro Serra of  the  University  of  Pisa,
       Italy (http://www-serra.unipi.it/) for hosting the ntop sites (both web
       and mailing lists), and Burton Strauss <burton@ntopsupport.com> for his
       help   and   user   assistance.  Many  thanks  to  Stefano  Suin  <ste-
       fano@ntop.org> and Rocco Carbone <rocco@ntop.org> for  contributing  to
       the project.



                            August 2005 (ntop 3.2)                     NTOP(8)
