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Fix typical connectivity issues

Husarnet status

For a brief status of the established connections, execute:

sudo husarnet status

The output will look something like this:

Husarnet IP address: fc94:7196:e39f:23ff:fe45:81aa:39e4:b224
UDP connection to base: [::ffff:]:5582
Peer fc94:9e5d:fef0:7bb4:00f1:fcb7:d85:fdaf
secure connection established
Peer fc94:a2e4:7b6b:322b:b200:97fa:e32f:a867
secure connection established

Let's analyse this information.

Connection to the Base Server

The second line contains information about connection to the Base Server. Base Server helps devices find each other over the internet.

UDP connection to base: [::ffff:]:5582

Normally, you should see information about successful UDP connection.

WARN: only TCP connection to base established

If there is only TCP connection established, you won't be able to establish direct connection to other devices over the internet. The data will be tunnelled over the base server - this will negatively impact latency and performance.

In order to fix this, unblock UDP on the firewall. You need at least UDP port 5582, but it's recommended to allow all outgoing connections.

ERROR: no base connection

This message means that most likely there is no internet connection. You will be only to contact devices in your local network.

Connection to a peer

Important: Make sure to ping the peer before checking its information in husarnet status - it is only updated when communication is attempted.

Each Peer fcXX:YYY section contains information about connection to a specific peer.

If the second line contains tunnelled, that means that you have no direct connection to the peer - this negatively impacts latency and performance. This is most likely caused by restrictive firewall, symmetric NAT or beeing behing carrier-grade NAT (CGNAT). Here are some tips on how to fix it:

  • allow all UDP traffic on the firewall
  • change NAT type to Full-cone or Port-restricted in your router configuration (it is often called Open or Moderate in router settings)
  • enable IPv6
  • restart your router
  • execute conntrack -F on Linux router or virtual machine host

Otherwise, there will be a line containing target=XXXX, where XXXX is the internet address used for communication with this node.

Tunneled connection when behind CGNAT

Some ISPs, usually mobile carriers, utilise carrier-grade NAT. As a result it is impossible to establish peer-to-peer connection with device hidden behind it.

How to check if you are behind CGNAT:

The easiest way is to check IP address given to you by ISP:

  • ICAAN allocated IP4 address block for CGNAT is, however some carriers utilise other private IP4 ranges, such as or
  • If there is a router in your network, login into its web panel and check IP on WAN.
  • In case of LTE modem plugged directly into your computer execute command in the terminal 'ip a' - and check IP on outbound interface

If you verified, that you are behind CGNAT and are unable to achieve peer-to-peer connection there is solution. Most ISPs offer service to get public external IP - contact with your ISPs customer service to obtain it. Its important to note, that it does not have to be static address - just public.


Hostnames of the devices in Husarnet network are stored in /etc/hosts in lines with # managed by Husarnet comment. They are modified automatically by the Husarnet daemon.

SSH connection issue

On some machines, before accessing them over SSH ($ssh user@husarnet_hostname command) you might see the following error:

ssh: connect to host husarnet_hostname port 22: Connection refused

To overcome that issue, execute in the terminal of the device you are trying to reach over SSH:

$ sudo apt-get install ssh
$ service ssh restart

Reporting problems

If you still have problems, you can report the problem by sending mail to Please describe your problem and attach Husarnet log. You can retrieve the log using the following command:

sudo journalctl --unit husarnet > log.txt


sudo journalctl --unit=husarnet --since=yesterday > log.txt

The log will be saved as log.txt in the current directory.

You can also report bugs on the public community forum.