You were redirected to because of
DNS resolution of '' will be stopped next
Please update your bookmarks
(see also misusage of

Carrier Grade NAT (CGN) Test Page


If you like ipv6calc, Deep Space 6 or you can donate via PayPal
Donate using Liberapay

In case you see only (parts of) one square filling in the IPv4 2D source port distribution and dots are changing colors to yellow/red, yellow/red lines in the histogram and the port reusage > 0%, your system is probably behind a Carrier-Grade NAT device.
During execution, browser window is blocked for at least shown estimated time
Unexpected behavior may occur when used via proxy or from a mobile device
This page requires JavaScript enabled!
Control Amount of connections to use for test:

for test use 8, for analysis 1024/2048 is a good choice

Workflow step
Time [s] Consumed/Left
Protocol IPv4 IPv6
Port Counter
Address Counter
Port Min/Max/Delta/Reusage
Source Port

each dot refers to
one source port
same port used a 2nd time
same port used >= 3 times
each x covers 256 ports
each y-dot covers up to 16 hits
and above 256 hits as y-dot
a line shows an overflow
Update of graphics every ms and status every ms (supported browser: 'Firefox/Seamonkey', there are known but unresolved issues at least with IE11/Windows 8 and Edge/Linux).

How it works using Javascript in local browser: Using Linux you can simulate the behavior of CGN using e.g. on the host itself by reducing source port range to 256 ports only: See also

(P) & (C) 2013-2021 by Peter Bieringer <> / Credits to Robert Eisele for pnglib.js
2021-10-28, webmaster at bieringer dot de

Your connection is via: IPv4
Your address:
is maintained by
webmaster at bieringer dot de
powered by Apache HTTP server powered by Linux