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Check network connections


nc -v -z <host> <port>
Tell me if we can open a connection to <host> on <port>. Without -z it works like telnet
nc -v -u -z <host> <port>
Tell me if we can open a connection to <host> on a UDP <port>


curl -vvv -k --proxy1.0 <proxyIP>:<proxyPort> <Remote URL>
Get the data from <remote URL> via <proxyIP> -k allows insecure SSL connections
curl -vvv telnet://<IP>:<port>
Just test connectivity to a port


wget <URL>
Get the data from <URL>


openssl s_client -showcerts -connect <IP>:443
Test SSL connection


ifconfig -a
Show all network interfaces
ifconfig <interface> <ipaddrss>
Assign <ipaddress> to <interface>
mii-tool <interface>
Show interface link status (speed)


ssh -L 8080:remotehost:3006 proxy
Login over ssh to proxy and there connect to remotehost port 3006. Connect local port 8080 to the remote connection.
Now if you connect to port 8080 on your local server you are connected to port 3006 on the remotehost
Using -nNT prevents that the ssh command opens a terminal on the proxy. The ssh command however must remain active.