network-protocols

问题 I read the RTP specification and I can't seem to get my head around the RTP Packet Timestamp. I tried to implement it in different ways in my server but I can't get the player to play it right. The "wrong" behaviour I'm having here is that ( I use VLC player to play the RTSP url to my server ) I find the logs of the player saying "buffer way too late" and "wrong PTS value" . Which means somehow that the audio frames arrives in a packets whose timestamp is not set right. I tried to implement

问题 Is SMTP based on TCP or UDP ? I really can't confirm it . In my opinion, SMTP should be based on UDP, but someone told me that is must be TCP. 回答1: In theory SMTP can be handled by either TCP, UDP, or some 3rd party protocol. As defined in RFC 821, RFC 2821, and RFC 5321: SMTP is independent of the particular transmission subsystem and requires only a reliable ordered data stream channel. In addition, the Internet Assigned Numbers Authority has allocated port 25 for both TCP and UDP for use

问题 Can anyone tell me what is the basic step to generate UDP, TCP and IP Packets. And how can i generate it using Python? 回答1: as suggested by jokeysmurf you might craft packets with scapy if you you want to send/receive usual packets then you should use socket or socketserver http://docs.python.org/library/socket.html#module-socket http://docs.python.org/library/socketserver.html#module-SocketServer to send TCP to google's port 80 use import socket HOST = 'google.com' # The remote host PORT =

问题 This may not be the typical stackoverflow question. A colleague of mine has been speculating that flow-based routing is going to be the next big thing in networking. Openflow provides the technology to use low cost switches in large application, IT data-centers, etc; replacing Cisco, HP, etc switch and routers. The theory is that you can create a hierarchy these openflow switches with simple configuration, eg. no spanning tree. Open flow will route each flow to the appropriate switch/switch

问题 How do I collect bandwidth usage/utilzation on devices/switches. From what I understand there are systems that do something like this. They seem to all have snmp in common. I am looking for imformation on possibly rolling my own system for collecting this data that will be later used on a web-based front-end. For a real-world but perhaps a bit over complicated example of what I'm talking about take a look at ubersmith de. Most of it will be in a LAMP environment. Thanks. 回答1: On pure SNMP

问题 Is it possible to import a Python module from over the internet using the http ( s ), ftp , smb or any other protocol? If so, how? If not, why? I guess it's about making Python use more the one protocol(reading the filesystem) and enabling it to use others as well. Yes I agree it would be many folds slower, but some optimization and larger future bandwidths would certainly balance it out. E.g.: import site site.addsitedir("https://bitbucket.org/zzzeek/sqlalchemy/src

问题 I cannot connect to my local SQL Server Express (2012, but the version shouldn't matter) from my server (Windows 2008 R2) to use a tool on it (APEX SQL Data Diff if you are wondering). I can browse the network servers fine, and select my local instance from the dropdown of available servers, but when I go to search tables on the server, it times out with this error message (same is true of SSMS). A network-related or instance-specific error occurred while establishing a connection to SQL

问题 I'm not 100% sure that I'm using the correct terminology or if I'm leaving out information that is required to answer. So please be patient with me. My client wants to include a video feed from an outside source inside a members area of their website. The members area is delivered over https and the video feed is not. Does this compromise the secure data? I know that some browsers alert the user that there are secure and non-secure data being loaded on the page. Frankly, my client is okay

问题 I'm thinking of running an experiment to track DNS values in different ways (like how often they change and whatnot). To do this I will need to be able to make a DNS request directly to a server so that 1) I known what server it came from, 2) I can request responses from several servers and 3) I can avoid the local OS run cache. Does anyone know of a library (c#, D, C, C++ in that order of preference) that will let me directly query a DNS server? Failing that, does anyone know of a easy to

问题 Currently I am doing a GPS Tracking project based on Django and GREENTEL It uses this protocol http://www.m2msolution.eu/doc/Fejlesztoi_dokumentaciok/GT03/GPRS%20Communication%20Protocol_GT03.pdf It says how to convert Latitude/ Longitude to Hex.. but I want to convert latitude hex data to the normal form Conversion method: A Convert the latitude (degrees, minutes) data from GPS module into a new form which represents the value only in minutes; B Multiply the converted value by 30000, and