General Overview Of A Transparent Proxy

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I cannot find out where I read this, but I found this on Reddit the other day. Not too specific, but just broad enough to give an overview of what a transparent proxy is and how to set one up.

To Resolve:

  1. Pick a software: Example Websense Triton-AP

  2. Setup an internal Certificate Authority and install the root cert for every domain joined PC via Group Policy

  3. Push out proxy settings via group policy as well. NOTE: Even if for some reason the client doesn’t have proxy settings then my router has a Policy Based Routing rule. Any port 80/443 traffic sent to the firewall is routed to the Websense Triton AP v5000 appliance.

SSL is decrypted and then re-encrypted and everything is logged.

The proxy can identify users by 2 methods:

  1. Domain Controller logs. It connects to all DCs in the domain and imports in the logs looking for the IP address & username that logged in associated with it then stores this in the DB. Any time it sees traffic from IP address X it assumes that it is user X based on the DC logs.

  2. NETBIOS query to the target device to ask who is logged on. If the DC log is > 1 hour old it will attempt to refresh via NETBIOS. If NETBIOS fails it falls back to DC logs.