[OLSR-users] Strange problem with the dyn_gw plugin

[stn21]

Hi Sven-Ola,

thank you, it seems I found the problem: my router Draytek Vigor 2200E
blocks UDP, as you said.
Windows-Tracert works because that uses ICMP, not UDP. Other linux-PCs
cannot traceroute either.

According to http://www.draytek.com.au/faq.php?category_id=26&faq_id=160
this is a fact. "UDP is blocked for security reasons". There is no
switch in the firmware to activate UDP, neither according to that page
nor did I find one. So apparently there is no workaround for this.

The draytek-site suggests using mtr instead of traceroute: MTR
(http://www.bitwizard.nl/mtr/). I have not checked this option.

As far as I can see this would mean that the freifunk-dyn-gw-plugin will
not function properly if the internet is accessed through this type of
Draytek-Router.

Stefan


> Stefan,
>
> if something is wrong on the IP level, use "ipkg update;ipkg install
> tcpdump". After this, you will be able to "tcpdump -ni vlan1" to
> narrow down what is wrong. Traceroute sends out packets (e.g. to a
> root nameserver as executed in /usr/sbin/cron.minutely) and starts
> with a TTL of 1. Next packet has TTL=2 and so on. The routers between
> you and the target need to respond with "ICMP TTL Exceeded". Maybe
> that ICMP (aka Ping) is blocked also.
>
> HTH Sven-Ola
>
> "stn21" <(spam-protected)> schrieb im Newsbeitrag
> news:(spam-protected)
>> Sven-Ola Tuecke schrieb:
>>> Hi,
>>>
>>> this is caused by a firewall setup of your itnernet gateway. In
>>> contrast to the standard dyngw plugin, freifunk uses a cronjob and
>>> traceroute to verify the intenet connection. Cron runs every minute or
>>> so. If traceroute not possible (e.g. UDP blocked), then HNA will
>>> switch off. You also may notice, that in this case a new
>>> "background-default-route" (aka policy routing) exist. The background
>>> route is only valid for the se505 device. This makes it possible to
>>> rescan with traceroute from the device itself while not disturbing
>>> others with a faulty standard default route.
>>>
>>> In short: Enable UDP and the auto-HNA is your friend.
>> Hi Sven-Ola,
>>
>> thank you for the hints. Traceroute from the freifunk-AP itself via
>> router into the internet does not work, as you suggested. The only
>> response comes from the internet-router.
>>
>> But:
>> - traceroute from a (windows-)PC via the AP via router into the internet
>> does work.
>> - UDP also works from a PC via AP via router into the internet.
>> - I know no way to test whether UDP works from the AP itself.
>>
>> This makes no sense to me. AFAIK UDP and traceroute are not blocked on
>> the internet-router. Do you have any idea why this happens?
>>
>> Thank you,
>> Stefan
>>
>>
>>>
>>> HTH Sven-Ola
>>>
>>> <(spam-protected)> schrieb im Newsbeitrag
>>> news:(spam-protected)
>>> Hi,
>>>
>>> I had another dyn-gw-problem with "freifunk"-firmware on a SE-505: I
>>> activated the WAN-port, and with or without explicit definition of the
>>> HNA-entry the AP reacted the same way. It announced HNA for about two
>>> minutes and then switched HNA and internet-routing off. A ping from
>>> the PC to the internet stopped responding, but ping from the AP itself
>>> showed that the WAN-connection was still active.
>>>
>>> The WAN-connection is by fixed IP to an internet-router.
>>>
>>> The easy solution was to deactivate dyn-gw and enter a fixed
>>> HNA=0.0.0.0/0
>>> Now it works. But Dyn-GW would be better because then HNA would switch
>>> off when the internet-connection fails.
>>>
>>> I was surprised that the HNA was also announced if I entered nothing
>>> in the HNA-field, even then it announced 0.0.0.0/0 (for two minutes)
>>>
>>> One question on dyn-gw: what happens when the connection from the AP
>>> to the internet-router is OK  but the router itself  has no connection
>>> to the internet? Is dyn-gw smart enough to switch off HNA in that
>>> situation?
>>>
>>> Stefan
>>>
>>>
>>>
>>> ----- original Nachricht --------
>>>
>>> Betreff: [OLSR-users] Strange problem with the dyn_gw plugin
>>> Gesendet: Mi 13 Sep 2006 13:58:54 CEST
>>> Von: "Jerome LEBEGUE"<(spam-protected)>
>>>
>>>> hi,
>>>>
>>>> I started playing with the dyn_gw a few days ago and I encountered a
>>>> very strange beahavior.
>>>>
>>>> I define an HNA as follow "HNA" "192.168.0.0 255.255.255.0" (wired
>>>> network) and to test if it is ok I define the following Ping parameter
>>>> "Ping" "192.168.0.30".
>>>>
>>>> My problem is that when the ping failed (I disconnect the cable and
>>>> get
>>>> the message "Do ping on 192.168.0.30 .... FAILED") my olsr node
>>>> continue
>>>> to announce the corresponding HNA :(
>>>>
>>>> Do you have any clues ?
>>>>
>>>> (I work on linksys WRT54G with OpenWRT and the corresponding OLSR
>>>> packages)
>>>>
>>>> PS: I waited several minutes to be sur it was not a remaining
>>>> announce.
>>>>
>>>> _______________________________________________
>>>> olsr-users mailing list
>>>> (spam-protected)
>>>> https://www.olsr.org/mailman/listinfo/olsr-users
>>>>
>>>
>>> --- original Nachricht Ende ----
>>>
>>>
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