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Old 25th August 2011
silverstream silverstream is offline
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Default pf routing to proxy

I've run into an odd problem trying to get pf to route properly to a proxy box. The set up we have is: individual testing PC, pf (OpenBSD 4.7), proxy (CentOS 5.2, Apache 2.2).

Code:
                                          Internet
                                            /     \
                                           /       \
                                          /         \
                                 proxy -------- firewall
                                                         |
                                                         |
                                                     test box
We're trying to get packets bound for any:80 from the test box to go to the proxy, then out to the Internet, then back through the proxy to the test box.

The rules for this are:
pass out quick on $ext_if proto tcp from $test_box to any port 80 rdr-to $proxy port 8080

(Test box and proxy IPs are obscured here, but they're spelled out in the actual rule.)

On the test box, the proxy works fine if it's set directly in Firefox. Otherwise, connections hang and no data is returned. Running tcpdump on the proxy, I can see the traffic coming in from the test box at first, but it never responds to any ack packets going back out from the proxy. On the firewall, tcpdump and pf -ss show the packets going from the test box to the proxy, but they're getting lost.

The proxy and test box are on two different private networks, but the proxy has a static route to use the firewall as its router when trying to reach the test box network.

Can anyone think of what the problem could be?

TIA.

Last edited by phoenix; 25th August 2011 at 06:43 PM.
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Old 25th August 2011
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jggimi jggimi is offline
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Without more information, such as the rest of your ruleset (including any NAT rules), I can only recommend the following:

1. Add logging to every rule, whether pass or block. Your desired packets may be matching an earlier "quick", or not matching this rule for some reason.
2. Use tcpdump(8) with pflog(4) on the firewall, to see what rules are used with the packets of interest. You want to determine if they are being lost due to a block rule, or a pass rule that is not redirecting packets.
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Old 25th August 2011
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jggimi jggimi is offline
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The more I think about your topology, the more I think this is an addressing issue. I wonder if your test box sends http to address a.a.a.a, and is not acknowledging unanticipated responses from address b.b.b.b.

Last edited by jggimi; 26th August 2011 at 05:49 PM.
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Old 26th August 2011
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jggimi jggimi is offline
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Gah. I hate auto-correcting text editors. I just repaired the previous post. It said "teddy" -- now it says "test".

Swype. Can't live without it, but sometimes .... it really is a pain.
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