I'm new in work with interprocess communication. I need you help and clear explanation. I have 2 applications. One of them is a service and one is a client. I've used QT/C++ to write them. When they are working on the one local PC - all is good. But I need to separate them.
So, I have a service on the PC with IP 192.30.82.101.
I connect it to bus using next code:
QDBusConnection connection = QDBusConnection::sessionBus();
connection.registerObject("/my/service/MyService", mySvc);
connection.registerService("my.service.MyService");
Also I have a client on the another PC with IP 192.30.82.40.
I connect my client using the next code:
QDBusServiceWatcher serviceWatcher = new QDBusServiceWatcher();
serviceWatcher->setConnection(QDBusConnection::sessionBus());
serviceWatcher->addWatchedService("my.service.MyService");
.....
myServiceProxy = new local::MyService("my.service.MyService",
"/my/service/MyService", QDBusConnection::sessionBus(), this);
I need to connect my client on the PC with IP 192.30.82.40 to the service on the PC 192.30.82.101. I don't know how to do this. I've found a few topics on the forum but I still don't understand what to do.
So, what I have found:
On the PC where is my service I have to add additional lines to /etc/dbus-1/session.conf:
<listen>tcp:host=<host>,port=<port></listen>
<listen>unix:tmpdir=/tmp</listen>
<auth>ANONYMOUS</auth>
<allow_anonymous/>
Here I have a question: Which IP address I have to use here (server or client)? Which port is used for DBUS (is it default port or how I can check it)? I have tried to set an IP address of my client PC, my service PC and different ports, and port 0, but I've got an error: Failed to bind socket "172.30.82.40:0": Cannot assign requested address.
On the client side I have to set DBUS_SESSION_BUS_ADDRESS with the same address: export DBUS_SESSION_BUS_ADDRESS=tcp:host=<host>,port=<port>.
I've tried to do this with different ports, with 0 port, because this means - use any free port. But I cannot start bus daemon with any port+IP configuration.
Also I've tried to connect client QDBusServiceWatcher to bus using the next code:
serviceWatcher->setConnection(QDBusConnection::connectToBus("tcp:host=<host>,port=<port>", "session"));
It was not successful.
I have no idea how to connect them to each other.
Can anybody, please, explain me how it should be, how does it work?
I want to clearly understanding how does it work?
I will be very grateful for any help. I hope for your kindness.
UPDATE
I have found how to connect my client to DBus bus via TCP:
On the PC where is my service I have to add additional lines to /etc/dbus-1/session.conf:
<listen>tcp:host=localhost,bind=*,port=6667,family=ipv4</listen>
<listen>unix:tmpdir=/tmp</listen>
<auth>ANONYMOUS</auth>
<allow_anonymous/>
Here we should add PORT. We can find it in dbus config file.
On the client side I have to set DBUS_SESSION_BUS_ADDRESS with corresponding address (IP of PC where is service):
export DBUS_SESSION_BUS_ADDRESS=tcp:host=192.50.88.10,port=6667,family=ipv4.
Thats all. We can check it just started dbus-monitor.
But now I have another issue: how to connect my client to my service?
I need to do something more to connect to my service.
I guess that this is something like:
QDBusConnection::connectToBus("tcp:host=<host>,port=<port>","connectionName");
I've tried to connect with any random name, but this is not correct.
So, my question is - where I can get correct connection name?
Correct answer to my question is:
On the PC where is one application add additional lines to
/etc/dbus-1/session.conf:
<listen>tcp:host=localhost,bind=*,port=6667,family=ipv4</listen>
<listen>unix:tmpdir=/tmp</listen>
<auth>ANONYMOUS</auth>
<allow_anonymous/>
Correct port you can find in dbus config file.
On the client side It's needed to set DBUS_SESSION_BUS_ADDRESS with
corresponding address (IP of PC where is service):
export DBUS_SESSION_BUS_ADDRESS=tcp:host=192.50.88.10,port=6667,family=ipv4.
To connect to session where is alive your remote app use the next
connection string:
DBusConnection::connectToBus("tcp:host=192.50.88.10,port=6667", "qt_default_session_bus"));
How to know session name? I've added log in my service:
qDebug() << "Connection name: " << connection.name();
Then started app, copy printed name and set it in my client.
Now it works!
Related
I'm using the C++ connector and one of the example code that goes along with it and it wont allow external connections to connect to my database when i change the host address from localhost to my computer's address where the server is running.
This connects perfectly without any problems:
con = driver->connect("tcp://127.0.0.1:3306", "Shawn", "my_pass");
But obviously this wont work when i change computers, so i set the host address to my computer where the server is running like this:
con = driver->connect("tcp://108.xxx.xxx.xxx:3306", "Shawn", "my_pass");
*x's stand for numbers to hide my IP
Why won't it connect?
I allowed Norton 360(takes over windows firewall) to accept any and all connections and ports from my program.
I gave the user "Shawn" the privledges necessary to accept all hosts via "%":
http://i.imgur.com/F92qeua.png
I get this mysql error:
http://i.imgur.com/OMAhtpg.png
You can also pass Socket parameter with this connection string.
or
you can try with the hostname instead of ipaddress.
if still youre issue is not resolved .Firewalls/iptables are enabled at server side so u need to stop it.
I can run my Qt DBus test by connecting to the session bus:
QDBusConnection connection = QDBusConnection::sessionBus();
connection.registerService(...)
....
TestserviceInterface testserviceInterface( .... , connection, &a);
But can I connect to this DBus from a different computer. I know I can do something like this:
connection = QDBusConnection::connectToPeer("tcp:host=127.0.0.1,port=45000", Testservice::ServiceName);
But how would I obtain the port? Whatever I have tried, there seems to be no connection. Or am I at the wrong path here and need to us Peer 2 Peer DBus instead of the session bus?
I am almost sure the service name is correct, as I can see it qdbusviewer. When I use dbus-monitor the output does not mean a lot to me, I cannot see any port, etc.
Any idea how I would be able to connect from another computer?
PS: I am aware that there is something like gabriel for tunnelling via SSH (http://gabriel.sourceforge.net/howto.html). This is not what I am up to, I am looking for a "direct connection".
Session bus daemon usually listens unix socket /var/run/dbus/system_bus_socket ( check your /usr/local/etc/dbus-1/session.conf config ) which means that you can't access it remotely via tcp. Start some kind of port forwarding on computer where bus daemon is running (using socat for example) or configure it to listen tcp.
You can use SSH to create a tunnel for DBus.
ssh -nNT -L ./dbus_on_local:/var/run/dbus/system_bus_socket user#remote
Explanation
This will create a local "file" (unix domain socket) dbus_on_local that you can connect to.
I have client server application that works with Firebird server. Everytime when clients connect to the server they(client apps) don't check if there is a network connection to the server so at this time my application sometimes freezes when the server computer is switched off or service has stopped, so first of all I need to check connection if remote host is switched on or at some port anything listening....
Before establishing the connection I need to check it and make sure server and service is running using Indy components.
Any ideas? also I can use IcmpClient to ping remote host and then establish connection but which is the most optimal way ?
If you just want to check if the server computer can be reached, you could do a "ping" to check that. However, if you want to check if a specific TCP port is open, then the only way to find that out is to actually do a proper connect, which leads to the "freezing" program while the connection times out if there is no-one listening on that port.
I'm using Qt to create TCP server using QTcpServer. Every time a client connects to server, I would like to know the remote host's IP address and port number. I tried searching documentation but couldn't find any information on this topic.
I know there should be a way, I'm just not able to figure it out. Help please.
QTcpServer won't tell you the address/port directly on an incoming connection but you can get it by getting the connected QTcpSocket from QTcpServer::nextPendingConnection() and then using QTcpSocket's peerAddress() and peerPort() methods.
I have a C++ Program listening for incoming socket connections on port 2222.
I have an Adobe AIR/Flex application that attempts to connect to it, when I click a button.
When I Connect To My Socket Over My Intranet, My C++ program hears and accepts the incoming socket connection and Everything Works Fine:
var Sock:Socket=new Socket("192.168.1.100",2222);
But When I Try To Connect Using My Real IP, I Get Error #2031:
var Sock:Socket=new Socket("76.18.24.118",2222);
Both programs are running on my laptop computer. I am behind a router, but have configured that router with port forwarding so that port 2222 maps to my laptop.
What Am I Missing? I am very new to this, so perhaps I'm missing something obvious to you smarties.
What does the error code mean (see your docs for socket)
Are you sure the receiving server process is alive?
The traditional starting point is Beej's guide
Port forwarding does not mean that you can use an external IP address, your laptop is still on the private 192.168 network. What it means is that when someone tries to connect on 78.18.24.118:2222 the router converts the IP address to 192.168.1.100:2222. This effectively allows you to run a server inside your network but allows an outside client to connect to you.
Look up DNAT for more information.