OPNsense is equipped with a fully featured forward caching (transparent) proxy. A caching proxy reduces bandwidth and improves response times by caching and reusing frequently-requested web pages. The Access Control Lists can be utilized for user authentication and or as (category based) web filter.
- Multi Interface Support
- Transparent Mode (including SSL/HTTPS)
- ICAP Support for Anti Virus/Malware Engine
- HTTP Proxy
- FTP Proxy
- User Authentication
- Access Control Lists (valid for both http(s) and ftp)
- (Compressed) Blacklist
- Category Based Web Filtering
- Can be combined with traffic shaper
User authentication can be done using OPNsense standard and built-in authenticators. Currently these include:
- LDAP (incl. Microsoft Active Directory)
- Local user manager
- No authentication
OPNsense supports fine grained access control, base upon:
- MIME types
- Banned IP’s
- Browser/User Agents
The proxy can be combined with the traffic shaper and take full advantage of its shaping features. Additionally it includes its own options:
- Maximum download size
- Maximum upload size
- Overall bandwidth throttling
- Per host bandwidth throttling
Category Based Web Filter¶
No need for additional plugins, such as squidGuard - as OPNsense has built-in category based web filter support. Main features include:
- Fetch from a remote URL
- Supports flat file list and category based compressed lists
- Automatically convert category based blacklists to squid ACLs
- Keep up to date with the built-in scheduler
- Compatible with most popular blacklist
The transparent mode means all requests will be diverted to the proxy without any configuration on your client. Transparent mode works very well with unsecured http requests, however with secured (SSL) HTTPS connection the proxy will become a man-in-the-middle as the client will “talk” to the proxy and the proxy will encrypt the traffic with its master key that the client is required to trust.
Using a transparent HTTPS proxy can be a dangerous practice and may not be allowed by the services you use, for instance e-banking.
WPAD And PAC¶
If a transparent proxy cannot be used, OPNsense still supports automatic proxy configuration via WPAD / PAC.
WPAD via DNS requires the web interface to run on the default HTTP port (TCP/80) which is also a security risk (MITM attacks). In such cases you should proxy the connection or avoid configuring the applicance from an untrusted network.
Configuration / How-tos¶
More information on how to utilize OPNsense’s proxy service can be found in: