Provided by: ifupdown-extra_0.33+nmu1_all 
NAME
network-test - check the network and test if everything is fine
SYNOPSIS
network-test -s [-vverboselevel]
DESCRIPTION
The network-test program will test your system's network configuration using basic tests
and providing both information (INFO), warnings (WARN) and possible errors (ERR) based on
the results of these tests. It will check and report on:
* Status of the network interfaces of the system including: link status,
IP addressing and number of transmitted packets and error rates.
* Accessibility to configured routes to external networks,
including the default network route, checking the routers configured
to give access to the network
* Proper host resolution, testing DNS resolution against a known host.
* Proper network connectivity, testing reachability of remote hosts using ICMP and
simulating a web connections to a remote web server (the web server used for the
tests can be configured through the environment, see below)
* Extra information of network connectivity using calls to external API services
including the actual Internet IPv4 address, IPv6 address as well as GeoIP
information (only if enabled by the user in the highest verbose level)
The program does not need special privileges to run as it does not do any system change.
However, the behaviour of the program when running as an unprivileged user is not the same
as running as system administrator (i.e. root). If the program is run as system
administrator it will try to run some tools that are only available to it to speed up some
of the tests.
The program relies on the use of ip, netstat, ifconfig, arp, nmcli, and (when running as
root and using Ethernet interfaces) ethtool or mii-tool, to obtain information about the
system's networking configuration (status of available interfaces and configured network
routes). It also uses ping, host, curl, and nc (netcat) to do tests of the network
connectivity and ensure that the host can connect to the Internet.
OPTIONS
-s The log messages are sent also to the local3 syslog facility. This is useful if the
script is run periodically (from cron) and the system administrator wants to
preserve the output in syslog
-v verbosity
Verbosity level is a value that defines the level of output information that the
script should use. Valid values are: 0 (silent run), 1 (show only error messages),
2 (Show error and warning messages), 3 (default level - show informational
messages), 4 (show detailed information) and 5 (Show information from external APIs
-IP address and GeoIP).
As the privacy policies of different external services vary. These services are
only queried if the user selects the highest verbosity level (5).
ENVIRONMENT
The program will, by default, check www.debian.org and its associated web server. If you
want to use a different check host you can setup the environment as follows:
CHECK_HOST
The name of a host to use when testing DNS resolution. By default 'www.debian.org'
CHECK_IP_ADRESS
The CHECK_HOST ´s IP address. By default defined with the following value:
194.109.137.218
CHECK_WEB_HOST
The web server to use for testing purposes when testing network connectivity. By
default it will use 'www.debian.org'
CHECK_WEB_PORT
The web server port of server CHECK_WEB_HOST that will be used for testing. By
default it will use TCP port 80..
CHECK_WEB_URL
A web service to test network connectivity by downloading some content. By default
it will use 'http://network-test.debian.org/moo'
CHECK_WEB_MD5
The MD5sum value of the content being checked.
CHECK_IP_URL
A web service used to determine the system's public IPv4 address. By default it
will use 'https://api.ipify.org'
CHECK_IP6_URL
A web service used to determine the system's public IPv6 address. By default it
will use 'https://api6.ipify.org'
CHECK_GEOIP_URL
A web service used to determine the system's Geographical information based on
public databases. By default it will use 'http://api.geoiplookup.net/'
EXIT STATUS
The program will exit with error (1) if any of the network checks fail.
BUGS
This program does not have super cow powers so it is unable to fix the errors by itself.
It is also unable to detect if the network is failing due to a local firewall policy been
in place so make sure you check your system logs with dmesg (1) to detect if some of the
active tests are being dropped due to your local firewall.
Other known issues that might make the program not work reliable are:
* IPv6: The program does not yet explicitly handle IPv6 only hosts, some of the
tests might be biased towards IPv4 and might fail in IPv6 environments.
* Proxies: The program does not check network connectivity for hosts that connect
through the Internet using a proxy gateway for services. The program might report
issues in hosts using proxies even when these might connect to the Internet
properly through proxied services.
* Firewall environments: some of the tests rely on direct connectivity to external
hosts, which are tested using ICMP queries (through the use of ping. These tests
might fail in hosts installed in networking environments with firewalls that block
outbound ICMP communication.
SEE ALSO
ip (8), ncmli (1), netstat (8), ifconfig (8), ethtool (8), mii-tool (8), ping (8), nc (1),
curl (1), and host (1).
AUTHOR
network-test was written by Javier Fernandez-Sanguino for the Debian GNU/Linux
distribution.
COPYRIGHT AND LICENCE
Copyright (C) 2005-2020 Javier Fernandez-Sanguino <jfs@debian.org>.
This program is free software; you can redistribute it and/or modify it under the terms of
the GNU General Public License as published by the Free Software Foundation; either
version 2, or (at your option) any later version.
On Debian systems, a copy of the GNU General Public License may be found in
/usr/share/common-licenses/GPL.