Need Help: Can only access some websites Comodo Blocking Internet?


I recently converted over to Comodo Firewall after i got fed up with Zone Alarm Pro (v7) hogging my system resources and making everything run slowly.

So far the firewall seems great but i’m having problems getting any access to certain web pages which i had no problem accessing when i was running ZA as my firewall.

I have a hunch that it might be to do with websites that need site certificates as one of them is a banking site. Eg of 2 sites i found that i can’t get access to and I can’t even access the cached version of the pages from google.

My system
Nod32 Antivirus
Windows XP Pro SP2

Originally i installed Comodo straight from my user account (Admin) in XP without disabling Nod32 but have since uninstalled Comodo, cleaned the registry entries and reinstalled in safe mode with default settings as per a suggestion from the Forums.

Curiously on 2nd install i did not need to define a zone for my router to get internet access, i had to do this the 1st time round.

I have tried clearing all entries for zone alarm to fully uninstall.

I have no application rules set apart from firefox which asked me permission for internet access when i connected to the net.

Have also tried checking the Skip loopback for UDP and TCP (Currently unchecked) as per another forum suggestion.

Have tried disabling the firewall and accessing the same sites but get the same result with the page loading bar getting stuck at about 50%. Comodo may still be blocking here as i read that there may still be some of Comodo’s backgound services running even though i’ve diabled the firewall.

Can anyone help me out, i would love to be able to keep using the firewall but need access to these sites.

Many thanks

The IP address of is The other one is
Check your logs to determine whether either of them is being blocked. I can load both sites in Firefox without a problem. It’s easier to export the log files in HTML format which you can subsequently open in either IE or Firefox. To do that, change the setup from “Today” to “Last 7 days”, right click anywhere in the list, choose “Export HTML”, give it a name and save it somewhere on your hard drive.

You might want to try clearing the cache in Firefox by going to Tools → Options → Advanced → Network (tab) → Clear cache (button). Firefox holds the last 8 pages you visited in cache unless you’ve got the browser configured to clear it on shutdown. That option is located in Tools → Options → Privacy → Private Data menu → Settings (button) and then checkmark the options you want FF to perform when you shutdown the browser.

Also, run both Wizards at the foot of the firewall “Tasks” menu.

Hi Zito

I exported the log but the only thing that is being denied access is dkservice.exe which is part of Diskeeper, I use it to defrag my system.

I always configure firefox to delete cookies and cache on exit so its not that.

The two wizards i am a bit skeptical about. The 1st one allows all access to my computer to an IP address that i define, i’m using wireless so don’t really want to give full access. The other sets internet access rights for whatever program Comodo finds that asks for internet access. Is it not better for me to define internet access rights manually when a program asks to access the net?

I know this is a bit of a strange problem. Does anyone know which background services Comodo runs and which to disable so that i can check if i can access the web pages without the firewall?

Some more info…

I cleared the Logs in Comodo and rebooted the PC. I get a new Outbound Policy Violation even before i open Firefox. Here’s the log entry

Log Scope:: Today

Date/Time :2007-11-09 18:24:10
Severity :Medium
Reporter :Network Monitor
Description: Outbound Policy Violation (Access Denied, Protocol = IGMP)
Protocol:IGMP Outgoing
Source: (My IP Address)
Reason: Network Control Rule ID = 5

After a google search i found out that the destination IP is a multicast ip address for Internet Group Management Protocol (IGMP).

“The range of addresses between and, inclusive,
is reserved for the use of routing protocols and other low-level
topology discovery or maintenance protocols, such as gateway discovery
and group membership reporting. Multicast routers should not forward
any multicast datagram with destination addresses in this range,
regardless of its TTL.”

My understanding is that the ip address is put out to discover other computers on my network. Just a quick double check though, is it safe enough to allow this and would it have anything to do with preventing access to certain websites?


I’ve solved the problem. I uninstalled Comodo and accessed the web pages i was having trouble with without a firewall. It just gave me the same problem, so Comodo wasn’t the problem after all.

The only thing that made sense was that it was something to do with my adsl router so i went into the configuration page to have a look. Turns out my MTU threshold was too high but for some reason was allowing me to load some web pages but not others. I lowered it to 1400 and everything is working fine now.

Now i can keep Comodo after all :slight_smile:

PS Thanks to Zito for his suggestions.