I m new to contiki. I used cc2650 sensortag and now i m using cc1310 launchpad. i use beagebone as a edge router and one cc1310 launchpad as a slipradio. everything works fine. i can open Coap and web and also i can get sensors data on web and coap.
now, i want to send sensor data on our own ipv4 cloud using tcp socket. but, i cant create tcp socket to my cloud. Is it possible to create ipv4 tcp socket directly from node?
#g-oikonomou #adamdunkels #farcaller can anyone suggest me how to create ipv4 tcp socket to 127.0.0.1 ip address and 1502 port?
Related
I need to be able to read/write to an Azure Service Bus Queue and for that, the hostname and ports need to be white-listed by my IT team.
The connection string is: "Endpoint=sb://[myappname].servicebus.windows.net;...".
I have tried the hostname with port 443 (assuming here), but that hasn't worked after white-listing. So now I tried writing to queue while capturing the traffic from Wireshark, but I am getting lost in all the network packet details there.
Can anyone please help me with this?
Thank you
TCP port is used by default for transport operations. Please have a try to open the port 5671 and 5672. We could get more information from AMQP 1.0 in Azure Service Bus and Event Hubs protocol guide.
Azure Service Bus requires the use of TLS at all times. It supports connections over TCP port 5671, whereby the TCP connection is first overlaid with TLS before entering the AMQP protocol handshake, and also supports connections over TCP port 5672 whereby the server immediately offers a mandatory upgrade of connection to TLS using the AMQP-prescribed model. The AMQP WebSockets binding creates a tunnel over TCP port 443 that is then equivalent to AMQP 5671 connections.
If you use a library, please have a try to set the ConnectivityMode to https (443 port)
ServiceBusEnvironment.SystemConnectivity.Mode = ConnectivityMode.Https
I m new to contiki and try to connect client ip 127.0.0.1 and port 502 to tcp server which is listening on 502 port but it always shows hostname not found or connection time out error. i tried contiki/example/http-socket. I want to send cc1310 launchpad sensor data on ipv4 server. can any one help me?
I have a fairly simple Rails app that connect to Postgres server (locally).
Uptil now, I was under the impression if not specified (socket in the database.yml) the pg client connect with postgres over TCP on a loopback interface.
Fyi,this is how my configuration looks like.
{:adapter=>"postgresql", :encoding=>"unicode", :database=>"scp_development"}
But I think I was wrong I can't sniff any packet over the loopback interface at port 5432.
sudo tcpdump -nnvvXSs 1514 -i lo0 dst port 5432
Which is letting me believe that it working over Unix domain socket.
So, is there a fairly reliable way to determine ...
Whether I'm connected to TCP socket or Unix socket?
How I can say a port is open or closed. What's the exact meaning of Open port and closed port.
My favorite tool to check if a specific port is open or closed is telnet. You'll find this tool on all of the operating systems.
The syntax is: telnet <hostname/ip> <port>
This is what it looks like if the port is open:
telnet localhost 3306
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
This is what it looks like if the port is closed:
telnet localhost 9999
Trying 127.0.0.1...
telnet: connect to address 127.0.0.1: Connection refused
telnet: Unable to connect to remote host
Based on your use case, you may need to do this from a different machine, just to rule out firewall rules being an issue. For example, just because I am able to telnet to port 3306 locally doesn't mean that other machines are able to access port 3306. They may see it as closed due to firewall rules.
As far as what open/closed ports means, an open port allows data to be sent to a program listening on that port. In the examples above, port 3306 is open. MySQL server is listening on that port. That allows MySQL clients to connect to the MySQL database and issue queries and so on.
There are other tools to check the status of multiple ports. You can Google for Port Scanner along with the OS you are using for additional options.
A port that's opened is a port to which you can connect (TCP)/ send data (UDP). It is open because a process opened it.
There are many different types of ports. These used on the Internet are TCP and UDP ports.
To see the list of existing connections you can use netstat (available under Unix and MS-Windows). Under Linux, we have the -l (--listen) command line option to limit the list to opened ports (i.e. listening ports).
> netstat -n64l
...
tcp 0 0 0.0.0.0:6000 0.0.0.0:* LISTEN
...
udp 0 0 0.0.0.0:53 0.0.0.0:*
...
raw 0 0 0.0.0.0:1 0.0.0.0:* 7
...
In my example, I show a TCP port 6000 opened. This is generally for X11 access (so you can open windows between computers.)
The other port, 53, is a UDP port used by the DNS system. Notice that UDP port are "just opened". You can always send packets to them. You cannot create a client/server connection like you do with TCP/IP. Hence, in this case you do not see the LISTEN state.
The last entry here is "raw". This is a local type of port which only works between processes within one computer. It may be used by processes to send RPC events and such.
Update:
Since then netstat has been somewhat deprecated and you may want to learn about ss instead:
ss -l4n
-- or --
ss -l6n
Unfortunately, at the moment you have to select either -4 or -6 for the corresponding stack (IPv4 or IPv6).
If you're interested in writing C/C++ code or alike, you can read that information from /proc/net/.... For example, the TCP connections are found here:
/proc/net/tcp (IPv4)
/proc/net/tcp6 (IPv6)
Similarly, you'll see UDP files and a Unix file.
Programmatically, if you are only checking one port then you can just attempt a connection. If the port is open, then it will connect. You can then close the connection immediately.
Finally, there is the Kernel direct socket connection for socket diagnostics like so:
int s = socket(
AF_NETLINK
, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK
, NETLINK_SOCK_DIAG);
The main problem I have with that one is that it does not really send you events when something changes. But you can read the current state in structures which is safer than attempting to parse files in /proc/....
I have some code handling such a socket in my eventdispatcher library. Only it still has to do a poll to get the data since the kernel does not generate events on its own (i.e. a push is much better since it only has to happen once when an event actually happens).
When a client connects to a server using TCP, a new socket is created for the TCP stream. Does the connection remain on the same port the connection was made or does it get changed to some other port?
The new socket is an application-level concept introduced because each established connection needs a unique file descriptor (also distinct from the listening file descriptor), which maps to, but isn't the same as, a TCP session. The session itself is identified by the combination of source and destination address and port. The source (client) port is usually chosen at random, while the destination (server) port is the listen port. No additional port is allocated.
The server use the same port to listen and accept new connection, and communicate to the remote client.
Let's me give you an example, (in linux system):
First, start a http server by python：
xiongyu#ubuntu:~$ sudo python -m SimpleHTTPServer 500
Serving HTTP on 0.0.0.0 port 500 ...
Second use nc command to connect to the http server, here we start two client by:
xiongyu#ubuntu:~$ nc 0.0.0.0 500
Use netstat to see the netstate of port 500:
xiongyu#ubuntu:~$ netstat -natp |grep ':500'
tcp 0 0 0.0.0.0:500 0.0.0.0:* LISTEN 54661/python
tcp 0 0 127.0.0.1:51586 127.0.0.1:500 ESTABLISHED 57078/nc
tcp 0 0 127.0.0.1:51584 127.0.0.1:500 ESTABLISHED 54542/nc
tcp 0 0 127.0.0.1:500 127.0.0.1:51586 ESTABLISHED -
tcp 0 0 127.0.0.1:500 127.0.0.1:51584 ESTABLISHED 54661/python
You can see, the http server use port 500 to LISTEN for the client, after a new client connected to the server, it still use the port 500 to communite with the client, but with a new file descriptor .
The socket associated with the new descriptor returned by accept on the server will use the same port on the server side of the connection as the original socket (assuming "normal" definitions where the client initiates the connection). The new socket will have a different client port number (the remote port from the server's point of view).