Ntop

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Ntop is a network traffic probe based on libcap, that offers RMON-like network traffic statistics accessible via a web browser.

Installation and configuration

Install the ntop package. The first run of ntop, you must set the admin password:

# ntop

Tango-inaccurate.pngThe factual accuracy of this article or section is disputed.Tango-inaccurate.png

Reason: The previous default /etc/conf.d/ntop does not exist anymore. A configuration file may be passed via the @file option, but that must be picked up (e.g. via Systemd#Drop-in_snippets) from the systemd service file, which - as a second point - does not work due to FS#41849. (Discuss in Talk:Ntop#Configuration)

Next, you need to edit the configuration file (/etc/conf.d/ntop) to adapt on your needs. Below is an example configuration, with the focus on the host to get as much as information from the hosts connections:

/etc/conf.d/ntop
# Parameters to be passed to ntop.
NTOP_ARGS="-K -W 2323 -i enp1s0,wlp2s0 -M -s -4 -6 -s -u ntop -c -r 30 --w3c -t 3 -a /var/log/ntop/http.log -O /var/log/ntop/ -q --skip-version-check 0"

# Location of the log file.
NTOP_LOG="/var/log/ntop/ntop.log"

Start the ntop systemd service and if you want to start ntop at boot, enable it.

Tips and tricks

Web interface

To access ntop's web interface, enter http://127.0.0.1:3000/ into your web browser. To make changes to the server, you will need to enter your username (default = admin) and password.

If ntop is not just used locally on your machine, but network wide by multiple users, you'd be better off by allowing SSL connections (https) only.

# ntop -W 4223

Additional paramethers are allowed. Now direct our browser to https://127.0.0.1:4223/.

You can also provide ntop with your own SSL certificate. Simply put it in ntop's config directory and name it ntop-cert.pem

# cd /etc/ntop/
# openssl req -x509 -nodes -days 365 
  \-subj '/C=US/L=Portland/CN=swim' 
  \-newkey rsa:1024 -keyout ntop-cert.pem -out ntop-cert.pem

Group and user

In order for the -u parameter to work properly and to make your ntop setup a bit more secure, you should create your own group and user for it.

# useradd -M -s /usr/bin/false ntop
# passwd -l ntop
Note: The passwd command here is optional, but recommended, as it will render the system more secure regarding your sshd.

Troubleshooting

**ERROR** RRD: Disabled - unable to create base directory (err 13, /var/lib/ntop/rrd)

Directory /var/lib/ntop/rrd/ may not exist. Create it and make sure it belongs to user nobody.

Please enable make sure that the ntop html/ directory is properly installed

If you receive this warning while trying to access the web interface, edit /etc/conf.d/ntop to include your IP and restart the daemon. For example:

NTOP_ARGS="-i enp1s0 -w 127.0.0.1:3000"

This is the IP you will use to access the web interface.