I am trying to send mail using smtp server but i am getting following Exception.
Please give me some advice..
System.Net.Mail.SmtpException: Failure sending mail.
---> System.Net.WebException: Unable to connect to the remote server
---> System.Net.Sockets.SocketException: A socket operation was attempted to an unreachable network 184.xx.xxx.xx:25
at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
at System.Net.Sockets.Socket.InternalConnect(EndPoint remoteEP)
at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception)
--- End of inner exception stack trace ---
at System.Net.ServicePoint.GetConnection(PooledStream PooledStream, Object owner, Boolean async, IPAddress& address, Socket& abortSocket, Socket& abortSocket 6, Int32 timeout)
at System.Net.PooledStream.Activate(Object owningObject, Boolean async, Int32 timeout, GeneralAsyncDelegate asyncCallback)
at System.Net.PooledStream.Activate(Object owningObject, GeneralAsyncDelegate asyncCallback)
at System.Net.ConnectionPool.GetConnection(Object owningObject, GeneralAsyncD elegate asyncCallback, Int32 creationTimeout)
at System.Net.Mail.SmtpConnection.GetConnection(String host, Int32 port)
at System.Net.Mail.SmtpTransport.GetConnection(String host, Int32 port)
at System.Net.Mail.SmtpClient.GetConnection()
at System.Net.Mail.SmtpClient.Send(MailMessage message)
--- End of inner exception stack trace ---
at System.Net.Mail.SmtpClient.Send(MailMessage message) at testEmail.Module1.Main() in E:\testEmail\testEmail\Module1.vb:line 17
From this messagge
A socket operation was attempted to an unreachable network 184.xx.xxx.xx:25
it seems that you cannot reach the SMTP address.
Check your internet connection and then check if the address is correct.
A Ping to the address or a tracerout can help you understand why you cannot contact the server, if the address is correct
The message tells me that your webserver has problems connectiong to your SMTP server. Are you sure the SMTP address is right?
Remember that some SMTP-servers need logon
Also some SMTP servers will not let you connect if your use a different IPS
I would change the SMTP to the one your ISP has.
You can try to connect to the SMTP with Telnet to check your connection
telnet YourSmtpAddress 25
Related
Using Boost v1.74:
int main()
{
auto ctx = boost::asio::io_context{};
auto socket = boost::asio::ip::tcp::socket{ctx};
auto ep = boost::asio::ip::tcp::endpoint{
boost::asio::ip::make_address_v4("192.168.0.52"),
80};
boost::asio::connect(socket, std::array{std::move(ep)});
std::cout << "Success!" << std::endl;
}
The IP address of my machine on my local network is 192.168.0.31/24, and so trying to connect to a non-existent address in the same subnet with the above code gives:
10:24:55: Starting /home/cmannett85/workspace/build-scratch-Desktop-Debug/scratch ...
terminate called after throwing an instance of 'boost::wrapexcept<boost::system::system_error>'
what(): connect: No route to host
10:24:59: The program has unexpectedly finished.
This is all expected. If I change the bottom octet of the subnet in the address (e.g. 192.168.1.52), then the app just waits for a few minutes - presumably because it sent messages to any routers to see if they own the requested subnet. There aren't any routers on my network, so it eventually times out:
10:27:39: Starting /home/cmannett85/workspace/build-scratch-Desktop-Debug/scratch ...
terminate called after throwing an instance of 'boost::wrapexcept<boost::system::system_error>'
what(): connect: Connection timed out
10:29:49: The program has unexpectedly finished.
Again, as expected. If I change the next octet (e.g. 192.167.0.52) instead, I would expect this to behave exactly the same as it is an equally unknown subnet as the previous. But it suceeds!
10:31:22: Starting /home/cmannett85/workspace/build-scratch-Desktop-Debug/scratch ...
Success!
This address is definitely not on my network:
$ ping 192.167.0.52
PING 192.167.0.52 (192.167.0.52) 56(84) bytes of data.
^C
--- 192.167.0.52 ping statistics ---
17 packets transmitted, 0 received, 100% packet loss, time 16368ms
So why is the code reporting that it is connected? And why is changing the second octet different to the third?
Any IP address of the form 192.168.xx.xx is a non-internet-routable network. This means no internet routers will route it. So the only way packets get routed off your subnet is if you configure a route on your own router or host. 192.167.xx.xx is an internet routable network, Presumable there is a host out there on the internet that uses the address you specified. So if you can connect your host to the internet, some internet router will get your packet to the address specified.
It's something related to my VPN. I didn't think it was relevant as the tunnel address is 10.17.0.60/16, but disabling it makes the above code work as expected.
Thanks to a suggestion by #dewaffled, Curl is showing that there is something on the otherside of this connection that is completing the TCP handshake, but after a timeout of a few minutes closes the connection.
$ curl -v http://192.167.0.52
* Trying 192.167.0.52:80...
* Connected to 192.167.0.52 (192.167.0.52) port 80 (#0)
> GET / HTTP/1.1
> Host: 192.167.0.52
> User-Agent: curl/7.74.0
> Accept: */*
>
* Recv failure: Connection reset by peer
* Closing connection 0
curl: (56) Recv failure: Connection reset by peer
I know nothing about how VPNs work, but I suspect this is an implementation detail of my particular provider. Hopefully this 'answer' will limit confusion for anyone else!
I wrote a small protocol stack to connect to KNX/IP routers. The mechanism is as follows:
Discovery_Channel: For discovery the client sends out an UDP/IP packet to multicast address 224.0.23.12. KNX/IP routers listen to this multicast address and reply. The KNX/IP router can potentially be connected to multiple KNX media, so the answer contains a list of services with IP addresses and port, the client can connect to.
Communication_Channel: The discovered services from all KNX/IP routers are presented to the user to select which service a connection should be made to.
The problem is that the answer from the KNX/IP routers sometimes doesn't contain a valid IP address, but just 0.0.0.0. In this case I need to take the IP address from where the packet came from. But how can I get this with (non-boost version of) asio?
My code looks like this:
/** client socket */
asio::ip::udp::socket m_socket;
/** search request */
void search_request(
const IP_Host_Protocol_Address_Information & remote_discovery_endpoint = IP_Host_Protocol_Address_Information({224, 0, 23, 12}, Port_Number),
const std::chrono::seconds search_timeout = SEARCH_TIMEOUT);
/** search response initiator */
void Discovery_Channel::async_receive_response() {
/* prepare a buffer */
m_response_data.resize(256);
/* async receive */
m_socket.async_receive(
asio::buffer(m_response_data),
std::bind(&Discovery_Channel::response_received, this, std::placeholders::_1, std::placeholders::_2));
}
/** response received handler */
void Discovery_Channel::response_received(const std::error_code & error, std::size_t bytes_transferred) {
// here the answer provided in m_response_data gets interpreted.
// #todo how to get the IP address of the sender?
/* start initiators */
async_receive_response();
}
So how can I retrieve the IP address of the sender in the Discovery_Channel::response_received method? I basically only have the packet data in m_response_data available.
On datagram sockets you can (should, likely) use async_receive_from.
It takes a reference to an endpoint variable that will be set to the remote endpoint on success.
I am creating a client application that connects to a server using a an ssl Websocket connection and an ssl Http (Keep-Alive) connection and I am using boost::beast package to do the same. So as to detect a dead connection i have implemented a simple ping-pong mechanism. These all work fine, but an issue comes up when handling the ping-pong failure. The issue is as follows:
For testing my code i connected to the remote server, sent few messages and then turned off my wifi. As expected after a certain period it detected that it did not receive any message from the server and it tried to do an async_shutdown for the http connection and an async_close for the websocket connection. First thing i noticed was that both these calls block their respective strands until the wifi is back up.
And after the wifi is up, the application tries to reset the stream before reconnect:
void HttpKeepAliveConnection::recreateSocket()
{
_receivedPongForLastPing = true;
_sslContext.reset(new boost::asio::ssl::context({boost::asio::ssl::context::sslv23_client}));
_stream.reset(new HttpStream(_ioContext, *_sslContext));
}
And reset ws variable for websocket:
void WebsocketConnection::recreateSocket()
{
_receivedPongForLastPing = true;
_sslContext.reset(new boost::asio::ssl::context({boost::asio::ssl::context::sslv23_client}));
_ws.reset(new WebSocket(_ioContext, *_sslContext));
}
Unfortunately it fails at either on_connect or on_ssl_handshake. Following are my logs:
156 AsioConnectionBase.cpp:53 (2018-08-06 15:34:38.458536) [0x00007ffff601e700] : Started connect sequence. Connection Name: HttpKeepAliveConn
157 AsioConnectionBase.cpp:122 (2018-08-06 15:34:38.459802) [0x00007ffff481b700] : Failed establishing connection to destination. Connection failed. Connection Name: HttpKeepAliveConn. Host: xxxxxxxxx. Port: 443. Error: Operation canceled
158 APIManager.cpp:175 (2018-08-06 15:34:38.459886) [0x00007ffff481b700] : Received error callback from connection. Restarting connection in a sec. Connection Name: HttpKeepAliveConn
159 AsioConnectionBase.cpp:53 (2018-08-06 15:34:39.460009) [0x00007ffff481b700] : Started connect sequence. Connection Name: HttpKeepAliveConn
160 HttpKeepAliveConnection.cpp:32 (2018-08-06 15:34:39.460515) [0x00007ffff481b700] : Failed ssl handshake. Connection failed.Connection Name: HttpKeepAliveConn. Host: xxxxxxxxx. Port: 443. Error: Bad file descriptor
161 APIManager.cpp:175 (2018-08-06 15:34:39.460674) [0x00007ffff481b700] : Received error callback from connection. Restarting connection in a sec. Connection Name: HttpKeepAliveConn
So I have 2 questions:
How do we close a connection if internet is down and a proper tcp close is not possible.
Before reconnecting what are the variables in boost::beast (or for that matter boost::asio as boost::beast is built on top of asio) that needs to be reset
Have been stuck trying to debug this for couple of hours. Any help is appreciated
EDIT
So I figured out where I went wrong. Both Alan Birtles and Vinnie Falco were right. The way to close a dead ssl connection after your ping timer has expired (and none of the handlers have returned yet) is
In your timer handler
_stream->lowest_layer().close();
For websocket
_ws->lowest_layer().close();
Wait for one of your handlers (typically read handler) to return with error (typically boost::asio::error::operation_aborted error). From there, queue the start of the next reconnect. (Do not queue the reconnect immediately after step 1, it will result in memory issues that I faced. I know this is asio 101, but is easy to forget)
For resetting socket, all that is required is for the stream to be reset
_stream.reset(new HttpStream(_ioContext, _sslContext));
For websocket
_ws.reset(new WebSocket(_ioContext, _sslContext));
I don't think asio::ssl::stream can be used again after being closed.
How do we close a connection if internet is down and a proper tcp close is not possible.
Simply allow the socket or stream object to be destroyed.
I have developed a webservice using a 3rd Party API on Visual Studio 2012. I run tested it on my local computer and everything works fine. I can get the response i want from the webservice. But when i host this webservice on my remote server, i get the below Exception.
System.ServiceModel.EndpointNotFoundException: There was no endpoint listening at <wsdlurl> that could accept the message. This is often caused by an incorrect address or SOAP action. See InnerException, if present, for more details. ---> System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it <serviceurl>:8080
at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception)
--- End of inner exception stack trace ---
at System.Net.HttpWebRequest.GetRequestStream(TransportContext& context)
at System.Net.HttpWebRequest.GetRequestStream()
at System.ServiceModel.Channels.HttpOutput.WebRequestHttpOutput.GetOutputStream()
--- End of inner exception stack trace ---
Server stack trace:
at System.ServiceModel.Channels.HttpOutput.WebRequestHttpOutput.GetOutputStream()
at System.ServiceModel.Channels.HttpOutput.Send(TimeSpan timeout)
at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.SendRequest(Message message, TimeSpan timeout)
at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)
at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)
So is it my server or is it the 3rd party server where the webservice is hosted? I did a telnet to the server but could not connect. My question is why am i able to run my webservice on my local computer but cannot run it on the server?
I have a system that sends out emails and queues them if volume increases.
If it's 1 or 2 emails per hour, it sends out fine.
On busier times, the queue gets backed up and soon email sending starts to fail.
I've load-tested the SMTP server from my local - no problems there.
However, when I try to do the load-test from my EC2 server
- which is in a private subnet of a VPC
- where outgoing traffic goes through a NAT
- and where we've set up our own DNS server
the first few go out fine - and the rest starts to throw errors.
Here's the C# exception ToString()
System.Net.Mail.SmtpException: Failure sending mail. ---> System.Net.WebExcept
ion: Unable to connect to the remote server ---> System.Net.Sockets.SocketExcept
ion: A connection attempt failed because the connected party did not properly re
spond after a period of time, or established connection failed because connected
host has failed to respond [SMTPServerIP]:25
at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddre
ss socketAddress)
at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Sock
et s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state,
IAsyncResult asyncResult, Exception& exception)
--- End of inner exception stack trace ---
at System.Net.ServicePoint.GetConnection(PooledStream PooledStream, Object ow
ner, Boolean async, IPAddress& address, Socket& abortSocket, Socket& abortSocket
6)
at System.Net.PooledStream.Activate(Object owningObject, Boolean async, Gener
alAsyncDelegate asyncCallback)
at System.Net.PooledStream.Activate(Object owningObject, GeneralAsyncDelegate
asyncCallback)
at System.Net.ConnectionPool.GetConnection(Object owningObject, GeneralAsyncD
elegate asyncCallback, Int32 creationTimeout)
at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint)
at System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint)
at System.Net.Mail.SmtpClient.GetConnection()
at System.Net.Mail.SmtpClient.Send(MailMessage message)
--- End of inner exception stack trace ---
at System.Net.Mail.SmtpClient.Send(MailMessage message)
at ConsoleApplication2.Program.Main(String[] args) in c:\ConsoleApplication2\
Program.cs:line 49
I'm pretty sure it's not a code issue - most likely a setting on the NAS or DNS.
Can someone point me in the right direction?
After some more googling - it seems to be a throttle on AWS' end
Source:
http://aws.amazon.com/ec2/faqs/
Q: Are there any limitations in sending email from EC2 instances?
Yes. In order to maintain the quality of EC2 addresses for sending email, we enforce default limits on the amount of email that can be sent from EC2 accounts. If you wish to send larger amounts of email from EC2, you can apply to have these limits removed from your account by filling out this form .
Better details here:
Amazon EC2/SES SMTP Timeout