p2psp team mailing list archive

[Max Mertens <max.mail@xxxxxxxxxx>]

Hi Vicente,

On 01.07.2015 23:31, Max Mertens wrote:
> On 29.06.2015 08:43, Vicente Gonzalez wrote:
>> No. But we can assume that the monitor peer will run always in the
>> same host that the splitter. If you configure the team in such way
>> the problem persists? In any case, I would like to know what is
>> happening ...
> Ok, and thanks for explaining the reasons for this setup.
> I have adapted the test to the new scenario, with monitor and splitter
> on the same host and two extra peers behind NATs. Output parsing is a
> bit more difficult here, I will write result tables as soon as the
> test fully works.
In fact the output parsing was working correctly, however the monitor
did behave strangely when running on the same host as the splitter:
To reach the internet and connect to the source server, the splitter
host had a second IP address 10.0.3.15, and apparently this address was
reported by socket.recvfrom to the monitor if a message is received from
the splitter on the same host. So the monitor recognized the splitter as
a peer, and it did not receive chunks from other peers, nor did it
forward chunks to them.
So I removed the internet network interface from the splitter host, and
instead added a local port forwarding using socat to the test script, to
let the splitter connect to the source (I didn't manage to setup a local
source, how can you achieve this? When using tools/run_a_source.sh, the
splitter prints "IMS: No data in the server!").
Now everything works as expected, and the peers successfully join the
team and can send packages to each other and the monitor, see the result
table below.

Sending keepalive packets seems not to be needed, as the connection
works well without. However if any issues in maintaining the connections
is experienced, I will try that as a solution.
So the next steps will be finishing the documentation until so far and
then continue the NTS implementation to handle symmetric NATs.


An unrelated question: To determine the address to listen on, in
Peer_IMS the public IP address is gathered by this code [1]:

    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.connect(("gmail.com",80))
    #my_ip = socket.gethostbyname(socket.gethostname())
    my_ip = s.getsockname()[0]
    s.close()

However it might not be possible (e.g. in a virtual machine setup where
the peers don't have a direct connection to the internet) or desired for
the peer to send packets to gmail.com. Would it be possible to do the
same technique but connect to the splitter IP address instead, as it has
to be reachable from the peers anyway?

Regards,
Max

[1] https://github.com/P2PSP/p2psp/blob/master/src/peer_ims.py#L99


Test results when the monitor is located on the same host as the splitter:

Splitter_LRS, Monitor_LRS, Peer_FNS (branch master, commit e4e16bd):

Peer1\2 | fcn    | rcn    | prcn   | sym   
=========================================
fcn     | yes    | yes    | yes    | yes
rcn     | yes    | yes    | yes    | yes
prcn    | no     | no     | no     | no
sym     | no     | no     | no     | no


Splitter_NTS, Monitor_NTS, Peer_NTS (branch nts, commit 395aa1e):

Peer1\2 | fcn    | rcn    | prcn   | sym   
=========================================
fcn     | yes    | yes    | yes    | yes
rcn     | yes    | yes    | yes    | yes
prcn    | yes    | yes    | yes    | no
sym     | yes    | yes    | no     | no