Networking – Testing a Firewall against outgoing UDP ports

firewallnetworkingportudp

I'm trying to test which outgoing ports are allowed through a firewall. At the moment I can do this for TCP by port scanning portquiz.net (which is a server with all TCP ports open) from inside however this won’t work for UDP.

My setup is as follows:
Me (my device on local network) <-> NAT/Firewall <-> IPv4 Internet

So my question is, how can I test a firewall between me and the Internet to see which outgoing UDP ports I am able to connect to and use successfully?

For clarification I'm wanting to test every port (not any particular port) and returning a list of the ports that can successfully get through.

Best Answer

This tool will do it. You can enter the entire 1-65,535 UDP port range.

http://demo1.speedsight.com/applet.html

Related Solutions

Networking – UDP packet and firewall

Possible reasons are (1) firewalls (2) wrong routing information (3) NAT somewhere on the path, even if you don't know about it.

Debug the network with traceroute and ping from both sides, see what is in between both computers, and see where the block is.

(As the question is 5 years old, it's unlikely to get more details...)

Networking – Detect what outgoing ports are bypassed by firewall

You can use portquiz.net, which is exactly the kind of server you're looking for. For example, following shell script does the job:

for x in `seq 1 65535`; do

    echo -ne "$x "
    curl "http://portquiz.net:$x" \
      --connect-timeout 1 \
      -o /dev/null \
      -q >/dev/null 2>&1 \
        && echo 'open' \
        || echo 'closed'

done | tee ports.lst

Note that this is going to run for quite a long time, so if you're impatient, you can parallelize the task using GNU parallel.

Also, some ports on portquiz seem to be blocked on their end (as far as I remember they're ports for SSH and HTTPS), but other than a few special cases, all of the remaining ports should be open.

Best Answer

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Networking – UDP packet and firewall

Networking – Detect what outgoing ports are bypassed by firewall

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