Software Defined - Wide Area Network (SD-WAN) Services And Their Implementation On An Open Source Linux Based Platform

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 Restricted-cone: Works in the same way as a Full-cone but applies additional 
restrictions based on an IP address. The connection must start form the internal 
client, and only the external IP address contacted can reply by setting the 
destination port the outbound NATed source port. 
 Restricted-port: Acts as restricted-cone but apply restriction also to the source 
port. Packet form external client in addition to the requirements of restricted-cone 
must set the source port equal to the destination port set by internal client.   
 Symmetric: Apply the same restrictions as restricted-port but the NAT does not 
do port reservation. The source port set by internal client is randomly changed by 
NAT. In this way there is a unique mapping for each connection. In addition to 
the requirements of restricted-port the external client must set the destination port 
equal to the source port randomly chosen by NAT.  
 UDP Firewall: Firewall that allow UDP out. The external client must respond to 
the client who sent the request, like symmetric NAT but without translation.  
 Blocked: Firewall that block UDP 
3.5 Etherws 
Etherws is a python library for the implementation of software switch with the Ethernet 
over WebSocket tunnel. The main components of Etherws are Ether SW, Ether CTL and 
TAP. Ether SW is a simple virtual Ethernet switch that is controlled by Ether CTL. To 
the Ether SW can be added the TAP device and port to existing network interface. The 
TAP device is the virtual network interface that has an IP address, and it’s responsible for 
passing the Ethernet packets to the WebSocket connection simulating a Ethernet device 
[24].