If I view an ebay listing through FireFox the main listing body is not displayed in it's place is a black box that says "Website blocked by Netgear Firewall", but:

1. I don't have website blocking enabled on my router
2. It happens only in FF, page displays correctly in IE & Chrome

A line from the router's log:

Fri, 2013-02-08 17:15:35 - TCP Packet - Source:121.1.0.90,49991 Destination:vi.raptor.ebay.com,80 - [BLOCK]

This has only started happening in the last couple of months, I upgraded the firmware last week which seemed to have cured it, but it hasn't.

Any ideas? I can't stand IE and I'm not overly fond of Chrome.

Cleared your caches lately?

I've just tried that, made no difference.

Is Firefox set to use a proxy on the router while the other browsers aren't?

Temporarily turn off all extensions?

Your router certainly things that you do have website blocking enabled.

Disabled all extensions/add-ons, still the same

Well, yes. But to check this I saved a copy of the log, cleared it and then visited the same page in IE, this did not create a log entry. Really strange.

It was set to "Use System Proxy", I've now turned proxy off, no change

Yeah, I'm with Mark Lord: That log file entry on your router certainly makes it look like the router is the thing blocking the site.

But the fact that the problem only occurs in Firefox is a bit of a stumper. Since IE and Chrome don't have a problem, it makes me wonder what's up on the router. So we go back to the router log:



What's that 49991 in there? Is that a TCP port number? What is Firefox doing sending a TCP packet on that port? If so, I'll bet *that* is what the router was blocking: The strange TCP port.

I would assume that it is a port number, the destination port is an http (80). Can't find anything on port 49991 on the web.

49991 was the source port number from the PC -- those numbers are chosen at random for each outgoing connection from the PC. Normal.

It might help to post more lines from the log.

Maybe it's some broken .js based browser-detection web-hackery. Does the problem still persist if you change Firefox's user agent setting?

Stretching a bit... since it's being blocked by the router, but only happens with Firefox, maybe Firefox is communicating with the server in a different fashion than Explorer or Chrome, and opening multiple connections. Thinking about how many ways iptables can be configured, perhaps the firewall is blocking the packets based on connection state.

How do you do that?

I've used the User Agent Switcher plugin fairly successfully.

OK, thanks but still no joy.

It was a long shot. Only other thing I can think of is to fire up something like netmon or wireshark, and see what the traffic pattern coming from Firefox is. Do you have any custom rules in your router firewall?

Routers can be very strange at times. Last night, my router decided to not talk to my notebook. I still have no idea what the problem was.

Symptom : Notebook receives no DHCP IPv4 address, nor establishes a valid routable IPv6 address. Issue is present on WiFi, ethernet via Thunderbolt monitor, and via a separate ethernet dongle.

Booting another machine on the network works fine. Restarting the notebook doesn't fix the issue. Rebooting the notebook into recovery mode (so a completely different isolated OS) doesn't fix the problem.

Rebooting the router, and connectivity came back. My best guess is some weird DHCP issue, though I didn't try a static IP assignment to fully verify. The notebook never fell back to a self assigned IPv4 address, even after 10 minutes.

I'm still boggled by tahir's problem as much as I was with mine last night.

That's the bunny! There's an option called "Close IM Ports" I unchecked that and eBay started displaying correctly.

I'd have never thought of that, thanks

Hm. Must have thought that 49991 port was an Instant Messenger.

Which, of course, it wasn't in that case, so, that feature on the router is made of fail.

Interesting. Only theory I can come up with is the random range of ports Firefox uses to connect out happen to be in a range blocked by that firewall rule. Other browsers likely have different ranges.

My old Hawking router use to do that about once a week or every other week, usually to my main PC. That was the primary reason I got rid of it.

The issue came back again last week, and static IP assignment fixed it. I use the Apple Airport router, and it looks like the newest firmware (7.6.3) has some bugs. Tied to both having extra Express units on the network and also IPv6 connectivity. I have both. And whenever the problem appeared, both IPv4 and IPv6 would fail to get addresses. The router logs would show the connection and address attempts, and strangely would try to treat my laptop as another wireless access point, even over ethernet.

Rolled back to the previous firmware (7.6.1) and so far the issue hasn't reappeared.