I am consistently seeing a 3+ second delay when opening a connection to a Unidata server via OpenAsync and the ADO.NET provider by Rocket.
What can I do to diagnose this delay?
I use jdbc and odbc connections all the time, and three seconds just ain't right.
You can start by breaking things down into client, network, server.
On the client, is it the same if you use an IP address vs hostname? If different, then DNS delay. Do you have any antivirus or other software that might be delaying connections? Can you turn that off, or do a test from a freshly configured machine?
For network, can you ping the unidata server in millseconds? Are there firewalls in the way? Can you install wireshark and filter packets by destination? Is there a delay when you ssh? Is the server configured with LDAP/AD, or local authentication - could be connecting to another server to authenticate?
On the server, you can turn on uniobjects logging, then restart unirpcd. Do you have something in your LOGIN/UOLOGIN that is hanging up the remote connection?
$cat $UDTHOME/serverdebug
udcs 9 /tmp/udcs.log
Related
I did a lot of research for following matter and I got a lot of helpful information but the matter still remains, so I'm going to write it with full details
I'm trying to run "Remote Server Administration" with VisualSVN Server (Enterprise Edition), the server is Windows Server 2008 connected to the internet via router with port forwarding to this server. The client is not at local network so I use a static IP for the server.
Also I did every things written at this URL: http://www.visualsvn.com/support/topic/00025/
but I still get the following error message Connot connect to WMI namespace "..." : the RPC server is unavalible (0x800706ba) when I'm trying to "connecting to another computer".
On the other-hand, I can browsing the "Repositories" content by any web-browser successfully.
How can I manage the Repositories at remote servers?
"...the RPC server is unavalible (0x800706ba)" error indicates a connectivity issue to the remote machine.
Accessing WMI remotely requires port 135 TCP/UDP and all TCP ports above 1024 (1024-65535) to be opened (and forwarded), by default. You can setup fixed port for WMI to simplify the port-forwarding / proxy setup task. In order to setup the fixed port, follow steps described in the article "Setting Up a Fixed Port for WMI". After you follow these steps you are required to setup port forwarding and proxy rewrites (if any) for 135 TCP/UDP and port 24158 TCP.
"...Access is denied (0x80070005)" error indicates insufficient permissions to access WMI remotely. Add your user account to the local group on the remote machine: "Distributed COM Users".
I use WebRequest in a client to consume a web service on Internet. Each request is triggered in a separate thread.
It works well if hosting the client in IIS. But most of the requests will get timed out error if the client is hosted in a windows service.
When I tried to debug the problem using Fiddler, the WebRequest worked well as all traffic went through 127.0.0.1:8888
Without Fiddler, the traffic goes to Internet directly through a random port, and the time out problem hits again.
The windows service runs under Local System account.
Why do I get time out if the client is in windows service without using a proxy?
Update: My original question wasn't clear. The requests are made concurrently (or at a very short interval). This is to do with the connection limit in the ServicePoint class. By default only 2 connections are allowed to the same external destination. If the destination is local, the limit will be int.Max value. That's why fiddler can magically fix the problem with the proxy. So I manually set the DefaultConnectionLimit to 100 and the requests are on wire.
Adjusting HttpWebRequest Connection Timeout in C#
The most common source of problems that is "magically" fixed by running Fiddler is when your .NET code fails to call Close() on the object returned by GetResponseStream(). See http://www.telerik.com/automated-testing-tools/blog/13-02-28/help-running-fiddler-fixes-my-app.aspx for more details.
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 have an application which connects a remote database server.
If mysql server stops for a reason and stars succesfully after that, my application cannot detect server status quickly. It takes nearly 20 seconds to reconnect to the database server. So my gui freezes. I do not want a gui freeze for 20 seconds
So far I tried
mysql_ping
mysql_real_connect
functions
MYSQL_OPT_RECONNECT
MYSQL_OPT_CONNECT_TIMEOUT
options
My enviroment is not multi-threaded. So
how to do a faster detection?
If you do networking synchronously, be prepared for freezes. For this very reason it makes sense to do data-manipulation in a separate thread.
You could try telnet to the mysql port (usually 3306). If you get a connection refused, mysql isn't listening.
Working.
root#XXXXXX:~# telnet localhost 3306
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
L
5.6.4-m7)#m#_8:W�hP5YBzaXs[MOmysql_native_password
Down.
root#XXXXXX:~# telnet localhost 3306
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused
The refused message is almost instant.
As already discussed by others, i won't talk about using multiple threads or processes. Can you connect to your mysql server on tcp? That way in most scenario's you would receive a tcp fin immediately to indicate a closed connection, though at times this might not be the case even. But most robust applications do a proper close.
shell> mysql --protocol=TCP
MYSQL how to specify protocol
If server doesn't accept it, i believe it can be enabled from config settings.
However, this does not address scenarios such as server suddenly gets off the network, or you client's connection is down etc.
How do I detect if a remote client is running Remote Desktop Protocol? and it is also accepting remote desktop connections ??
Like Open an port to detect HTTP and send request, receive request headers and see in request headers information about HTTP so I will know the person is running HTTP weather if he changed the port e.g: running HTTP 6551.
Attempt and make a connection with something that is RDP-connection aware (RDP is not HTTP). Of course, failing to establish an initial handshake is not proof that a connection can not be established. It could be blocked by a firewall, listening on another port, etc.
The MS-RDPBCGR specification, page 16 talks about connecting which in turn defers to X.224, go figure.
It'd likely just be easiest to use Wireshark and observe in-the-wild behavior to develop a minimal detection case. I suspect only the very initial portion of the handshake needs to be generated/replayed in order to "decide" that it's a listening RDP server.
(Or, perhaps use an existing RDP client which has this "test connect" functionality or the ability to be scripted.)
A fast way is to pen a shell and type
telnet IPADDRESS 3389
If you get a connection, chances are good that an RDP server is on the other side. RDP can run on any port, but TCP Port 3389 is set per default.
Windows 7 requires some extra steps to enable the telnet Client.
You could do netstat -a in the command line and see if the default port for remote desktop connection is listening, ie. TCP:3389 but thats only if the client hasn't changed the ports for MSTSC