Important note about SSL VPN compatibility for 20.0 MR1 with EoL SFOS versions and UTM9 OS. Learn more in the release notes.

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How to Find / Prove ISP blocking port access

GavinDaniels

Hey Guys,

I am trying to work out why I am unable to access the web interface of some customers Sophos Firewalls. This has only begun to occur recently. I believe it is an ISP Proxy / block issue, but I cant find a way to prove this to the relevant ISP's.

I have access to a number of Sophos XG firewalls, all running 17.x firmware. From my office networks (multiple computers) I am not able to access the web interface of 3 firewalls. I am using their IP Address. All 3 of these are using the same ISP. This ISP is not the one I use.

I can Ping the units. I can SSH to the units (When I enable these in the Device Access) but I cannot access the HTTPS page.

Other Sophos units connected with other ISP's I can access without issue.

2 of the 3 units I can't access have a secondary WAN connection (one is 4g, the other is ADSL) I can access the web interface on those specific IP address.

If I change my ISP connection to my portable 4G unit (Connected to another port on my Sophos XG running V18) I can connect fine.

If I run up a VPN from my office machine I can connect fine.

From one of the 3 units, if I teamviewer to a machine on their network, I can access the web interface of the other machines on that ISP, plus the web interface of my office Sophos unit.

 

I am looking for tools I can setup and use which will point to where the issue lies. Is there a way I can Telnet to the web port and get a page dump which will tell me if there is a transparent proxy? Was easy to do with HTTP requests, I dont know how to do it with HTTPS ones.

Is there a utility which will do an open on every device between my link and the other firewall so I can determine which intermediate device is blocking the request.

 



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  • 0

    Hi Gavin,

    I can't answer your question directly, but why don't you use the CFM to access all your supported firewall?

    Ian

    XG115W - v20.0.2 MR-2 - Home

    XG on VM 8 - v21 GA

    If a post solves your question please use the 'Verify Answer' button.

Reply
  • 0

    Hi Gavin,

    I can't answer your question directly, but why don't you use the CFM to access all your supported firewall?

    Ian

    XG115W - v20.0.2 MR-2 - Home

    XG on VM 8 - v21 GA

    If a post solves your question please use the 'Verify Answer' button.

Children
  • 0 in reply to rfcat_vk

    Hello.

     

    One of the customers has specific corporate compliance, which includes audits by Price Waterhouse Coopers, and registration with CFM is against the IT policies.

    Regards,

    Gavin Daniels. DipIT(Networking)

     

     
  • 0 in reply to GavinDaniels

    Hi Gavin,

    seems a little odd that they would prefer having the XG advertise itself to the internet rather than a tunnel initiated within the XG, but every company to its own IT security policy?

    Ian

    XG115W - v20.0.2 MR-2 - Home

    XG on VM 8 - v21 GA

    If a post solves your question please use the 'Verify Answer' button.

  • 0 in reply to rfcat_vk

    Hello

    HTTPS on this site is not enabled by default. On others it is.

    While I do see connection attempts logged in the firewall, nobody has gotten into one as yet

    On this site I VPN in, but there are some changes where I decide I need a reboot, so I open the web port, do my work then turn it off.

     

    Regards,

    Gavin Daniels. DipIT(Networking)

     

     
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