Provided by: ntop_5.0.1+dfsg1-2ubuntu1_amd64 
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|--protocols <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-sessions] [-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|----output-packet-path <path>] [-P|--db-
file-path <path>] [-Q|--spool-file-path <path>] [-U|--mapper <URL>] [-V|--version] [-X
<max_num_TCP_sessions>] [--disable-instantsessionpurge] [--disable-mutexextrainfo] [--disable-ndpi]
[--disable-python] [--instance] [--p3p-cp] [--p3p-uri] [--skip-version-check=yes] [--w3c] [-4|--ipv4]
[-6|--ipv6]
Unix options:
[-d|--daemon] [-i|--interface <name>] [-u|--user <user>] [-K|--enable-debug] [-L] [--pcap_setnonblock]
[--use-syslog= <facility>] [--webserver-queue <number>]
Windows option:
[-i|--interface <number|name>]
OpenSSL options:
[-W|--https-server <port>] [--ssl-watchdog]
DESCRIPTION
ntop shows the current network usage in a web browser, the default URL is 'http://localhost:3000'. 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 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 ntop 3.1, many command-line options may also be set via the web browser interface. These
changes take effect on the next run of ntop and on each subsequent run until changed.
-a | --access-log-file
By default ntop does not maintain a log of HTTP requests to the internal 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 protocols 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 problems 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 memory.
By default idle hosts are periodically purged from memory. An idle host is identified when no packets
from or to that host have been monitored 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 eligible 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. Especially 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 interface 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 ( ntop 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 interface. Any traffic on those networks
is considered local. This parameter 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 notation 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 information 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/services 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 specified 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 looking 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 ntop 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 network 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 promiscuous 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 analyze 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 privileges 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 security 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/, where "hostname" is the name or address of the system where ntop is installed.
For example, if ntop is installed on the local machine, the web interface can be accessed at
http://localhost:3000. If started with a full specification, 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:// connections.
-W operates similarly, but controls the port for the https:// connections.
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 protected by a userid/password. By
default, these are the user/URL administration, filter, shutdown and reset stats are password protected
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 performance 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 generated/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 available at
http://www.tcpdump.org/tcpdump_man.html - for further information 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 network 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 significantly 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 interface.
-F | --flow-spec
It is used to specify network flows similar to more powerful applications 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 expression>']
, 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
concerning flows can be accessed following the HTML link named 'List NetFlows'.
For instance define two flows with the following expression LucaHosts='host jake.unipi.it or host
pisanino.unipi.it',GatewayRoutedPkts='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 myFacilityNames.
-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 Windows 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 initialization 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 discussions about purge timeouts. This switch makes ntop respect the
timeouts 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 protective mutexes it uses. Since ntop
uses fine-grained locking, this information is updated frequently. On some OSes, the system calls used
to collect this information (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 information 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 ./configure --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 ntop 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 'libraries
in' value looks OK, go with the library.
--p3p-cp
--p3p-uri
P3P is a W3C recommendation - http://www.w3.org/TR/P3P/ - for specifying personal information a site
collects and what it does with the information. These parameters allow ntop 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 turning an interrupt driven process into a poll), it also MAY
significantly increase 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=yes
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 ntop webserver hangs. These usually happen when connecting 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 'BETTER' (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 information using their web browsers. ntop
does not generate 'fancy' or 'complex' 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
current 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 capabilities.
--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 information 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://people.ee.ethz.ch/~oetiker/webtools/rrdtool/
ntop includes a limited version of rrdtool 1.0.49 in the myrrd/ directory. Users of ntop 3.2 should not
need to specifically install rrdtool.
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 create 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=yes 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 automatically 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 version 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 kernrlse/2.4.20-8smp
GCC/3.2.2 config(i18n) run(i; u; P; w; t; logextra; m; instantsessionpurge;
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 consists 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 available).
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)
subscription 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 <stefano@ntop.org> and Rocco Carbone
<rocco@ntop.org> for contributing to the project.
August 2005 (ntop 3.2) NTOP(8)