On 20/02/16 12:31, vastik_spbm wrote:
>> On 19/02/16 14:53, vastik.spbm@yahoo wrote:
>>> Dear all,
>>>
>>> I will explain my problem.
>>> My ISP decided to fight with torrents DHT and changed udp nat
>>> translation timeout to 5 seconds.
>>> What does it mean. It means that if udp packet won't return from
>>> destination within 5 seconds NAT wont create a new rule and wont allow
>>> any other packets goes back to source. To create nat rule the first
>>> packet has to return with in 5 seconds, and it doesn't matter if other
>>> packet will follow the first one, the rest can return much later, but
>>> first one has to return within 5 seconds.
>>>
>>> Right now my client cant connect to any nodes at all. This is initial
>>> connection, when I start my client.
>>> And this can be done by any of ISPs, it is not very difficult and ISP
>>> doesn't brake anything, because UDP exists and enabled.
>>> Freenet wont work this way.
>>>
>>>
>>> Therefore, please:
>>> You need to improve node behavior - it has to replay nearly
>>> immediately after a node receives an attempt to initiate a connection
>>> from a client.
>>> It doesn't mean that node will keep it up, node can reject this
>>> connection late, or just ignore any other packets from client, but not
>>> the first one.
>>>
>>> Sorry, English is not my native language to me, so if you need more
>>> details or log file from tcpdump, just ask.
>>> I use freenet a lot and would like to continue to use it.
>>>
>> I believe Freenet does reply more or less immediately to a connection
>> request. Did your node manage to connect to any seednodes? Have you
>> tried connecting to darknet nodes outside the problematic network?
>>
>> It might be losing connections to seednodes once it's established them.
>> Currently on an idle connection we send keepalive packets only every
>> 7-14 seconds (see the constant KEEPALIVE_INTERVAL in Node.java, you
>> could just reduce this to say 2 seconds). Another possibility for
>> darknet would be to ensure there is always traffic e.g. by sending files
>> using the node-to-node messaging.
>>
>> However, there are two further problems:
>>
>> 1. Some NATs will break Freenet no matter what we do. E.g. if they use a
>> different port number for each connection, UDP hole punching usually
>> won't work, at least not if the other side is also NATed.
>>
>> 2. It's actually fairly straightforward to block Freenet at present. The
>> trivial attack is to block large UDP packets, but there are other
>> options. In the long run with steganographic transports this would be
>> harder, but still easy with traffic flow analysis (depending on how much
>> of a problem false positives are i.e. blocking other traffic by
>> accident).
>>
> Hello,
>
> I would like to apologize for the noise.
>
> I found access to a different ISP and check response time, it is less
> then 3 seconds.
> If necessary I can provide log, but I do not think.
>
> It looks like my ISP did some nasty stuff to block some udp (sip
> actually works).
> I am not sure that ISP uses different port number, because sip stun
> tells that nat is symmetric.

IIRC symmetric means exactly the problem above: Different port number
for each pair of IPs, can only connect to nodes that aren't NATed. :(

> Yes my node can ONLY connect to seednodes:
>
> 15:18:51.567601 IP 192.168.1.2.35394 > 100.xx.xx.xxx.14416: UDP,
> length 272
> 15:18:51.750478 IP 192.168.1.2.35394 > 84.xx.xx.xxx.1131: UDP, length 231
> 15:18:53.617665 IP 192.168.1.2.35394 > 149.xxx.xxx.xxx.61078: UDP,
> length 285        <---- this is request to seednodes, packet size
> correspond with others
> 15:18:53.662938 IP 149.xxx.xxx.xxx.61078 > 192.168.1.2.35394: UDP,
> length 325        <--- replay, almost immediately
>
> As long as I cant check the remote side I think I just say thank you
> for your help.
>
>
> Best regards
> Vasilii Tikhonov

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