Troubleshooting

Running network tests

To diagnose a network issue, you can perform different tests.

MTR test

An MTR test combines the functions of traceroute and ping on all points between two machines.

When running an MTR test, it is important to do it in both directions:

• From the server to the IP of your connection
• From your connection to the server

On Linux

You have to check that the mtr packet is installed.

sudo apt-get install mtr
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or

sudo yum install mtr
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On Windows

1. Download the application from its project page.

2. Extract the archive and run the executable.

3. Enter the target (IP) of your test in the Host textbox, then click on Start. Wait one or two minutes before you stop the test. You can then make a screenshot or export the result with the functions of the software.

Example of MTR between a Scaleway Dedibox server and free.fr:

root@163-172-30-2:~# mtr --report free.fr
Start: Sun May  1 16:23:57 2016
HOST: 163-172-30-2                Loss%   Snt   Last   Avg  Best  Wrst StDev
1.|-- 163-172-30-1.rev.poneytel  0.0%    10    0.5   0.5   0.4   0.5   0.0
2.|-- 195.154.1.248              0.0%    10    1.6   1.0   0.9   1.6   0.0
3.|-- 195.154.1.254              0.0%    10    1.2   1.4   1.2   2.6   0.3
4.|-- th2-crs16-1-be1503-t.intf  0.0%    10    1.3   1.3   1.1   1.4   0.0
5.|-- p11-crs16-1-be1001.intf.r  0.0%    10    4.5   3.0   1.4   4.5   0.7
6.|-- p11-9k-1-be1000.intf.rout  0.0%    10    1.5   2.1   1.4   3.5   0.6
7.|-- bzn-9k-2-sys-be2001.intf.  0.0%    10    1.7   1.8   1.6   2.8   0.0
8.|-- www.free.fr                0.0%    10    1.2   1.2   1.2   1.2   0.0
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The results show:

IPERF test

With an IPERF test you can check the available bandwidth of your server.

The iperf server ping.online.net has several ports available (5200-5209). If the server is busy on the default port, you can specify another port using the -p flag, for example: -p 5203 (5204, 5205, etc.).

On Linux

If iperf is not yet installed on your server, you can install it with the following command:

sudo apt-get install iperf3
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or

yum apt-get install iperf3
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Then launch the test:

root@163-172-30-2:~# iperf3 -c ping.online.net -R
------------------------------------------------------------
Client connecting to ping.online.net, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  3] local 163.172.30.2 port 36490 connected with 62.210.18.40 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  1.10 GBytes   943 Mbits/sec
If your server is located at Amsterdam execute: root@163-172-30-2:~# iperf3 -c ping-ams1.online.net -R
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On Windows

1. Download the tool from its website.

2. Choose the latest version and download the file.

3. Extract the file.

4. Open a terminal and run the following command:

\iperf3.exe -c ping.online.net -p 5203
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The results show:

If your server’s network port is off

Sometimes when you change the mode of your dedicated server from normal to rescue mode during the reboot of a server, you may see the following error message in your console:

If this message is visible for a longer period or cycles every 5 minutes, it means your server is either distributing unauthorized traffic in the style of DHCP, distributing a MAC address that is not assigned to the server, ARP requests, too many requests per second in sending or receiving on your server.

If you continue to see this message, empty the cache of your browser as the old page may be kept in it. Alternatively, you can reload the page several times until the message disappears.