Solved

Using PF to rdr all http/https traffic to a web-scanning proxy

Posted on 2006-07-17
8
448 Views
Last Modified: 2013-12-23
I want to redirect all the outgoing traffic on port 80 to force it to go through the proxy held at messagelabs.  At the moment the rdr rule looks like

rdr on $int_if proto tcp from any to any port http -> 216.82.251.227 port 3128

This doesn't work.  I actually am a bit confused by what that does - if the proxy is not in the browser configuration then all pages fail.  If the proxy is in the configuration then it works.

Can anyone suggest how this ought to work with pf on openbsd?
0
Comment
Question by:chemwatch
  • 3
  • 2
8 Comments
 
LVL 51

Expert Comment

by:ahoffmann
Comment Utility
sorry I'm not used to pf, but is it a full statefull inspection firewall which handles the way back automatically?
If not you probably need a rule for the packets back from the proxy to your clients.
0
 

Author Comment

by:chemwatch
Comment Utility
The beauty of a redirect is that there should actually be no need to treat the return path specially.  Redirect will rewrite the destination of each outbound packet to be the web-proxy, but the source of the packet will still be the IP of the nat host that is sending it.
0
 
LVL 51

Expert Comment

by:ahoffmann
Comment Utility
do you see the requests at your proxy? If so, does it send the response back to the client?
I'd use tcpdump on the proxy host.
0
Enabling OSINT in Activity Based Intelligence

Activity based intelligence (ABI) requires access to all available sources of data. Recorded Future allows analysts to observe structured data on the open, deep, and dark web.

 

Author Comment

by:chemwatch
Comment Utility
We don't house the proxy - it is run by an outsourced company in singapore, to which we have no access.
0
 
LVL 51

Expert Comment

by:ahoffmann
Comment Utility
ok, then use tcpdump on your firewall, if you see the outgoing packets but no corresponding incomming, then the problem is at the proxy site
0
 
LVL 1

Accepted Solution

by:
robbak earned 250 total points
Comment Utility
Transparent Proxying - which is what you want to do - should be allowed to talk to the firewall to work out where the request came from. At the very least, it needs to know that it is supposed to be a transparent proxy. In squid, this is a compile-time option.

It seems that the remote proxy is not set up to act as a transparent proxy.

The best option I can see is to run a proxy on the local system. You don't need to give it a large cache - Indeed, none at all will work - and then have it use the other proxy as a parent. If you wish to go this way, then post back and we'll help you.
0

Featured Post

How your wiki can always stay up-to-date

Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
- Increase transparency
- Onboard new hires faster
- Access from mobile/offline

Join & Write a Comment

Don’t let your business fall victim to the coming apocalypse – use our Survival Guide for the Fax Apocalypse to identify the risks and signs of zombie fax activities at your business.
ADCs have gained traction within the last decade, largely due to increased demand for legacy load balancing appliances to handle more advanced application delivery requirements and improve application performance.
Viewers will learn how to connect to a wireless network using the network security key. They will also learn how to access the IP address and DNS server for connections that must be done manually. After setting up a router, find the network security…
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.

771 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

10 Experts available now in Live!

Get 1:1 Help Now