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Hello,

I noticed that after I upgraded my DGL-4300 firmware from 1.6 to 1.8, I am getting alot of "ICMP Type 3" outbound errors.

In my case, I am running BitTorrent on the IP address 192.168.0.4. Here is the ICMP error that appears many many times in my logs:

  Quote
Blocked outgoing ICMP packet (ICMP type 3) from 192.168.0.4 to 82.19.182.195

I have noticed that since these errors have been occurring, my Bittorrent speeds have been suffering

I would be grateful for any help =D

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ICMP type 3 is "Destination Unreachable"

I would assume your machine on 192.168.0.4 is whating to tell 82.19.182.195 -- that where they are trying to go is unreachable.. an your router is blocking this for some reason?? Why you would block this info I have no idea??

The actual details would be in the message.. ie here are the details of a ICMP type 3 message

http://www.networksorcery.com/enp/protocol/icmp/msg3.htm

Some examples of codes that the message would include;

1 Host unreachable error.

2 Protocol unreachable error. When the designated transport protocol is not supported.

3 Port unreachable error. When the designated transport protocol (e.g., UDP) is unable to demultiplex the datagram but has no protocol mechanism to inform the sender.

Is 192.168.0.4 the machine running BT? Is it running it on the same port as before? Is 192.168.0.4 some other router you have daisy chained in a double nat nightmare??

  BudMan said:
ICMP type 3 is "Destination Unreachable"

I would assume your machine on 192.168.0.4 is whating to tell 82.19.182.195 -- that where they are trying to go is unreachable.. an your router is blocking this for some reason?? Why you would block this info I have no idea??

The actual details would be in the message.. ie here are the details of a ICMP type 3 message

http://www.networksorcery.com/enp/protocol/icmp/msg3.htm

Some examples of codes that the message would include;

1 Host unreachable error.

2 Protocol unreachable error. When the designated transport protocol is not supported.

3 Port unreachable error. When the designated transport protocol (e.g., UDP) is unable to demultiplex the datagram but has no protocol mechanism to inform the sender.

Is 192.168.0.4 the machine running BT? Is it running it on the same port as before? Is 192.168.0.4 some other router you have daisy chained in a double nat nightmare??

Indeed, BudMan. The only things that have changed is the updated version of the torrent client, and updated firmware for the DGL-4300.

There were new options for TCP / UDP endpoint filtering, but I set those to "Endpoint independent". My SPI is turned off, and I can confirm that my ports are correctly forwarded. I even tried it with uPnP. Same errors.

However, the message given in my logs is simply that it blocked an outgoing ICMP packet from my LAN IP to an external IP (I am assuming this is a sort of bittorrent traffic, because it appears very frequently from my computer running bittorrent, but I am not entirely sure. Is this caused by DHT or Peer-Exchange? There is only one router that is connected to a bridge modem (no firewall, nat).

Destination unreachable can also mean PORT, icmp type 3 can be alot of things.. See my link for details. If the router tried to forward the traffic to the machine on port say 666, it could be the machine sending back - nothing on that port. "Destination unreachable"

Got to love this kind of nonsense logging;

"the message given in my logs is simply that it blocked an outgoing ICMP packet from my LAN IP to an external IP"

What is the freaking point?? Did it log the actual packet somewhere? Can you tell it to log the packet somewhere?

if you really want to get to the bottom of it.. Take a sniffer an look at the traffic on the wire.. Then you will know for sure what is going on. Wireshark is FREE and easy to use, just install it on the 192.168.0.4 machine -- which is where your router is saying the traffic is coming from.

http://www.wireshark.org/

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