-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 (taking this back to the list)
On 2014-02-26 14:55, Martin Peach wrote: > On 2014-02-26 03:47, IOhannes m zmoelnig wrote: >> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 >> >> On 2014-02-26 04:57, Martin Peach wrote: >> >> >> how come? how does DNS (after all, a central service in the >> internet) work with this assumption? >> >> UDP works fine with as a challenge/response system (less so as >> client/server, given that there is no notion of a "connection"), >> and for responses you need o be able to send messages somewhere. >> >> for whatever reasons, many hardware manufacturers have the idea >> that sending/receiving on the *same* port is a good idea. > > I see; but for DNS with [udpsend] and [udpreceive], it should work > since one [udpsend] can send to port 53 of the DNS server and a > separate [udpreceive 53] will receive its replies. it seems i was a bit unclear here, and thus two separate things got mixed up: - DNS is a bi-directional protocol: you send a query (from a random port N) to a DNS-server (on port 53), and the server sends a response from port 53 to that port N. - hardware-manufacturers like the idea that the receiving port is the same as the sending port. DNS does not have this limitation of using the same port (thus you can query a DNS-server on localhost without stepping on your own ports). so having both [connect dns.server 53(->[udpsend] + [udpreceive 53] is not sufficient to query a DNS-server. > The problem seems to be that [udpsend] will assign itself a random > port to which the remote device will send replies, but [udpsend] > doesn't know its own port number. well, but that's only half of the solution (for the DNS-problem): even if [udpsend] had a notion of it's sending port, it would discard all messages arriving on this port. but it still *listens* on (and thus blocks) this port, so you cannot tell a [udpreceive] to (also) use it. fg,asd IOhannes -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Icedove - http://www.enigmail.net/ iQIcBAEBCAAGBQJTDf0gAAoJELZQGcR/ejb4+3gP/jHgX0wRrIBNPPMC92+y8ssL dokmoX/tQa5ZYhPwcUg68xwORPKzldql2PsMx1hY19ud9kzoIbFXmfy/uBk9mTNX VATEb2d7vMY5lk3/iGApefl+gnugm9rCPyD88J80U/Q5gRDBUvCFH1hbtABXccRA AXRGRcZ5C9pMYPlCE6R0O4EF0553Dudscsitu2/wMx+hpqAfdS51bIbwSd6vU56I CGIc3QIohipwnQmhMQ9EAdFD/i3zxXg2xuC5HzHpc/Q4hipsuw0169V19pn6ucFM yx6iKW2j6P60QW3D7y8betwyBOmRfgpyF9ip4AkDvWqZuzfng0YxAWco3v9rDpvZ PITxRicLL50EyemI1rms6mPiw6nWmATfbYSQBPGdxTG/J6vUBlijNdrl1FdEIv0n 7dyLOLMk4rmfGivSrKFBsX2JcicPPapUv9grpm4d277mIn+oFhMVurfWHHp5DiPJ m66KkWMYwiAqK1+TjMzI+PI9yK+3gYZy54ExXi8/xxlZjC1F8nNHNv0ti2z+uk/Z DUERnsE42nzZ2pxNKTsSkaNv3GHMAFe0H7MRsdUD5+3CrtqBuHLpyJIQxjEHmP/4 /BGNhFJXiGnK+MOb84/8kq2W0QkYoIvF2LDdUUV/qNbj1Z0b0Ft1cRJjBwELX5Is iDAK9hFfnmz7uzdFkVur =s8u4 -----END PGP SIGNATURE----- _______________________________________________ Pd-dev mailing list Pd-dev@iem.at http://lists.puredata.info/listinfo/pd-dev
