i want to check my server connection to know if its available or not to inform the user..
so how to send a pkg or msg to the server (it's not SQL server; it's a server contains some serviecs) ...
thnx in adcvance ..
With all the possibilities for firewalls blocking ICMP packets or specific ports, the only way to guarantee that a service is running is to do something that uses that service.
For instance, if it were a JDBC server, you could execute a non-destructive SQL query, such as select * from sysibm.sysdummy1 for DB2. If it's a HTTP server, you could create a GET packet for index.htm.
If you actually have control over the service, it's a simple matter to create a special sub-service to handle these requests (such as you send through a CHECK packet and get back an OKAY response).
That way, you avoid all the possible firewall issues and the test is a true end-to-end one. PINGs and traceroutes will be able to tell if you can get to the machine (firewalls permitting) but they won't tell you if your service is functioning.
Take this from someone who's had to battle the network gods in a corporate environment where machines are locked up as tight as the proverbial fishes ...
If you can open a port but don't want to use ping (i dont know why but hey) you could use something like this:
import socket
host = ''
port = 55555
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))
s.listen(1)
while 1:
try:
clientsock, clientaddr = s.accept()
clientsock.sendall('alive')
clientsock.close()
except:
pass
which is nothing more then a simple python socket server listening on 55555 and returning alive
Related
Maybe (hopefully) I'm missing something very simple, but I can't seem to figure this out.
I have a set of gRPC services that I would like to put behind a nghttpx proxy. For this I need to be able to configure my client with a channel on a non-root url. Eg.
channel = grpc.insecure_channel('localhost:50051/myapp')
stub = MyAppStub(channel)
This wasn't working immediately through the proxy (it just hangs), so I tested with a server on the sub context.
server = grpc.server(executor)
service_pb2.add_MyAppServicer_to_server(
MyAppService(), server)
server.add_insecure_port('{}:{}/myapp'.format(hostname, port))
server.start()
I get the following
E1103 21:00:13.880474000 140735277326336 server_chttp2.c:159]
{"created":"#1478203213.880457000","description":"OS Error",
"errno":8,"file":"src/core/lib/iomgr/resolve_address_posix.c",
"file_line":115,"os_error":"nodename nor servname provided, or not known",
"syscall":"getaddrinfo","target_address":"[::]:50051/myapp"}
So the question is - is it possible to create gRPC channels on non-root urls?
As confirmed here, this is not possible. I will route traffic via subdomains in nghttpx.
I'm experimenting with LuaSocket for a project I'm working on. I've chosen UDP as my protocol.
Looking for docs and tutorials online, I've attempted to create a client-server pair for testing and learning.
According to what I've read, the following code should work. However, only the server seems to be working properly. The client sends a message, but it will not receive the reply from the server.
Thank you for any help anyone can provide.
Server:
-- Server
#!/usr/bin/env lua5.1
local socket = require("socket")
udp = socket.udp()
udp:setsockname("*", 53474)
udp:settimeout(0)
while true do
data, ip, port = udp:receivefrom()
if data then
print("Received: ", data, ip, port)
udp:sendto(data, ip, port)
end
socket.sleep(0.01)
end
Client:
-- Client
#!/usr/bin/env lua5.1
local socket = require("socket")
udp = socket.udp()
udp:setpeername("127.0.0.1", 53474)
udp:settimeout(0)
udp:send("Data!")
data = udp:receive()
if data then
print("Received: ", data)
end
The timeout value you set is 0, which causes the client timeout every time.
To fix it, give it a positive timeout value:
udp:settimeout(1)
Or set it to nil or a negative value, so it blocks indefinitely:
udp:settimeout()
or
udp:settimeout(-1)
I'm using rabbitMQ server with amq.
I am having a difficult problem. After leaving the server alone for about 10 min, the connection is lost.
What could be causing this?
If you look at the Erlang client documentation http://www.rabbitmq.com/erlang-client-user-guide.html you will see a section titled Connecting To A Broker
This gives you a few different options that you can specify when setting up your connection to the RabbitMQ server, one of the options is the heartbeat, as you can see the default is 0 so no heartbeat is specified.
I don't know the exact Erlang notation, but you will need to do something like:
{ok, Connection} = amqp_connection:start(#amqp_params_network{heartbeat = 5})
The heartbeat timeout is specified in seconds. So this would cause your consumer to heartbeat back to the server every 5seconds.
Also take a look at this discussion: https://groups.google.com/forum/?fromgroups=#!topic/rabbitmq-discuss/u227xzvqOr8
The default connection timeout for the RabbitMQ connection factory is 600 seconds (at least in the Java client API), hence your 10 minutes. You can change this by specifying to the connection factory your timeout of choice.
It is good practice to ensure your connection is release and recreated after a specific amount of time, to prevent eventual leaks and excessive resournces. Your code should ensure that it seeks a valid connection that is not close to be timed-out, and re-establish a new connection on the ones that did time-out. Overall, adopt a connection-pooling approach.
- Java example:
ConnectionFactory factory = new ConnectionFactory();
factory.setHost(this.serverName);
factory.setPort(this.serverPort);
factory.setUsername(this.userName);
factory.setPassword(this.userPassword);
factory.setConnectionTimeout( YOUR-TIMEOUT-IN-SECONDS );
Connection = factory.newConnection();
I have a custom device with a TCP/IP stack implemented that's sending a byte each 5 seconds to a remote IP.
On that remote IP, I'm building a site with rails 3.1.3 that will have to receive, store and display the data sent by the custom device.
I was thinking on having a TCP Socket running in the background, something like this, but i don't have a clue on how to integrate this with a rails site. Where to place it, how to start it and how to propagate the data to the views.
Does anybody have a clue on how shall I proceed?
To solve this I created a raketask that starts a TCP Server that will handle messages.
Note: This code has more than a year so I'm not 100% sure how it behaves, but I think the core part is this:
#server = TCPServer.new(#host, port)
loop do
Thread.start(#server.accept) do |tcpSocket|
port, ip = Socket.unpack_sockaddr_in(tcpSocket.getpeername)
begin
loop do
line = tcpSocket.recv(100).strip # Read lines from the socket
handle_message line # method to handle messages from the socket
end
rescue SystemCallError
#close the sockets logic
end
end
end
I am developing a chat application.
But Right now chatting is possible with only google because I know only google's port no.
xmppClient = [[XMPPClient alloc] init];
[xmppClient addDelegate:self];
// Replace me with the proper domain and port.
// The example below is setup for a typical google talk account.
[xmppClient setDomain:#"talk.google.com"];
[xmppClient setPort:5222];
You can see that, google has set 5222 as port number.
Same way I want to set port no for yahoo, windows messenger & other popular sites, How can I get all these?
(Is it something like that - "XMPP is specific for Google ones" ? ? )
Kraken's Openfire Properties Page has the port and domain information you need. Just re-use and try with your application.
5222/tcp is the default port for XMPP, but your implementation may have a different one. To find out, you do a DNS SRV query for _xmpp-client._tcp.YOURDOMAIN, where you replace YOURDOMAIN with the domain you're trying to connect to. This will return 0+ records that have hostname/port combinations for how to connect. If you get 0 records back, assume port 5222.
For example, I want to connect to the GoogleTalk server, and log in with the account foo#gmail.com. My client performs the lookup that can be simulated with dig on the command line like this:
% dig +short -t SRV _xmpp-client._tcp.gmail.com.
20 0 5222 talk1.l.google.com.
20 0 5222 talk4.l.google.com.
5 0 5222 talk.l.google.com.
20 0 5222 talk3.l.google.com.
20 0 5222 talk2.l.google.com.
The result with the lowest priority number is 5 0 5222 talk.l.google.com., which means you open a TCP connection to talk.l.google.com on port 5222.
To make SRV queries from code, check out this answer, which relies on DNSServiceQueryRecord.
5222 is the default port for XMPP, but
your implementation may have a
different one. To find out, you do a
DNS server query for
_xmpp-client._tcp.DOMAIN_Name, where you replace DOMAIN_Name with the
domain you're trying to connect to(ex.
gmail.com,google.com,yahoo.com). This
will return 0+ records that have
hostName/port combinations for how to
connect. If you get 0 records back,
assume port 5222.