Port 500 & 4500 blocked by TPG

[Uzie]

Hi

For the last 4 weeks my work vpn is connecting but after successful connection there is no internet connectivity, however, before that it was working absolutely fine. 

My IT has advised everything is fine at their end and issue could be due to Ports 500 & 4500 which are blocked due to which this issue is coming, I have run a test which clearly shows port 500 specifically used for VPN connectivity is blocked. When asked from TPG they said "we are not blocking any ports". I am really frustrated and dunno what to do, issue is where i live there is no nbn connectivity and only option left is to switch to some other ISP.

Advice on how to get port 500 and 4500 unblocked will be appreciated. 

Regards

[david64]

Hi @Uzie . First off, you have the wrong syntax for nmap command. It should be:

nmap -sU -p U:500,4500 -Pn 192.168.1.204

Check UDP ports 500 and 4500.

This only seems to be checking your home computer whether ports 500 and 4500 are open, which they probably aren't.

Could you explain your situation more clearly.

Are you trying to connect from your personal/work computer at home to the work VPN?

Does that connection use ports 500 and 4500 at the work end?

You can try using nmap specifying the ip address of the work VPN to check ports 500 and 4500.

What do you mean when you say "where i live there is no nbn connectivity"?

How are you connected to access this Community?

[Uzie]

Hi @david64 ,

Thanks for the reply.

I have updated the syntax and the result is still same. 

Yes I am trying to connect from my work computer at home to the work VPN

and that connection uses ports 500 and 4500 at the work end?

You can try using nmap specifying the ip address of the work VPN to check ports 500 and 4500.

Do i need to do this on work computer or that can be done thru my personal laptop too?

What do you mean when you say "where i live there is no nbn connectivity"?

How are you connected to access this Community?

I am accessing this community as I am using TPG 5G wireless broadband internet at my place. 

Regards

[david64]

@Uzie . This was working previously on 5G broadband? Last 4 weeks has been different?

What do you mean by "after successful connection there is no internet connectivity"? Does the VPN keep working? Do you lose internet on your own computer? 

You can use your work computer but don't start the VPN connection, if you have that option.

Or, you can use your own computer. You need the ip address of the VPN computer at work.

You can also try  telnet  command:

telnet ipaddress portnumber

A blank window indicates a TCP connection.

[david64]

@Uzie . If nmap can't get to work VPN, try  ping  and  tracert  commands to check network path to work. Use your own computer.

[Uzie]

Hi @david64 

Yes, the issue has surfaced since last 4 weeks and before that everything was working fine. 

On my work computer, prior to connecting to vpn, general internet browsing is fine e.g google.com but as I connect to the vpn, all internet connectivity is lost and am unable to open any site which is very strange. Whereas, internet keeps working fine on my personal computer. So what I have isolated is that the problem is purely related to my work VPN.

From my personal laptop, I performed the telnet IPAddress (VPN Work) 500(Port) and it says "connect failed".

for tracert to work vpn request times out 

5 * 31 ms * 203-220-16-185.tpgi.com.au [203.220.16.185]
6 41 ms * * nme-apt-bur-wgw3-be80.tpgi.com.au [203.29.135.145]
7 24 ms 32 ms 27 ms 27-32-160-129.static.tpgi.com.au [27.32.160.129]
8 42 ms 36 ms 39 ms syd-gls-har-crt1-be-10.tpgi.com.au [202.7.171.173]
9 42 ms 42 ms 35 ms syd-sot-ken-crt1-he-0-3-0-0.tpgi.com.au [202.7.162.74]
10 * * * Request timed out.
11 * * * Request timed out.

Regards

[Uzie]

Hi @david64 

For work VPN IP address, the ping and tracert both failed .

Regards

[david64]

@Uzie . On the basis that the VPN connection does still work, the difference is the work computer loses direct internet connectivity.

When the work computer is connected to VPN, can you still access the internet indirectly via work?

VPN software can work in 2 ways and 4 weks ago, your work might have made a change to how it operates.

Before, you could do direct internet browsing from the work computer, then start VPN, and have your direct internet and work connection side by side.

Now, it's like the VPN is disabling all prior connections or absorbing them into the VPN connection.

That is the question to ask at work.

I don't know why telnet fails. Telnet is TCP and work might only accept UDP.

How did nmap go when you test the work ip address?

There's a problem in TPG network restricting ICMP traffic (ping and tracert).

[Uzie]

Hi @david64 ,

I have checked from my IT and they have confirmed that no update has been done at their end so it seems more of a TPG NW issue. 

Since its a 5g broadband modem, port forwarding cannot be activated too, any advice that how can I get these two ports activated via TPG?

Regards

[Uzie]

Hi @david64 

The Nmap suing work VPN is okay for port 500 adn 4500