PostgreSQL supports using unix sockets rather than TCP sockets. How do I configure the following block to use unix sockets.
# Configure your database
config :my_app, Sample.Repo,
adapter: Ecto.Adapters.Postgres,
database: "ecto_simple",
username: "postgres",
password: "postgres"
As of March 2018, Postgrex now supports connecting via sockets.
This can be done by supplying a socket or socket_dir option. Here's the changelog from where I picked this up and the source code where you can see an exhaustive list of all options.
From the source code:
:socket_dir - Connect to Postgres via UNIX sockets in the given directory;
The socket name is derived based on the part. This is the preferred method
for configuring sockets and it takes precedence over the hostname. If you are
connecting to a socket outside of the Postgres convention, use :socket instead;
:socket - Connect to Postgres via UNIX sockets in the given path.
This is especially useful (I suppose) if you're on AppEngine which requires you to connect through an SQL proxy through localhost (127.0.01) which works only through a proxy connection.
PostgreSQL prefers unix sockets to TCP sockets on the grounds of performance and privacy. If not already available: TCP can be enabled on the server if you follow simple documentation and have access to do so.
The avenue of client connection is set via environment variables, in particular: PGHOST. From experience drivers such as libpq expect to work that way - it would be shocking if Postgrex did not.
See: https://hexdocs.pm/postgrex/Postgrex.html
The value to supply in PGHOST varies according to the configuration of the server as seen in the file: "postgresql.conf".
It is possible that you may need to create a directory for sockets and set permissions. The following should help: http://iamvery.com/2013/06/17/postgresapp-with-unix-socket.html
To get a more precise answer you will need to mention your operating system and version; also your version of PostgreSQL.
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I have written a oracle client program using OCI library.
client send a request to server and hung because server crashed and not intimated to client.
How can i find server status from client side(using OCI API).?
Thanks
I think Oracle db module for Asterisk had a nice DCD(dead connection detection) implemented. There are various approaches(server side, client side).
In your case the easiest way would be to use TCP keepalive. Use enable=broken directive in tnsnames.ora.
Purpose
The keepalive feature on the supported TCP transports can be enabled
for a net service client by embedding (ENABLE=BROKEN) under the
DESCRIPTION parameter in the connect string. Keepalive allows the
caller to detect a dead remote server, although typically it will take
2 hours or more to notice. Operating system TCP configurables, which
vary by platform, define the actual keepalive timing details.
net_service_name=
(DESCRIPTION=
(enable=broken)
(ADDRESS=(PROTOCOL=tcp)(HOST=sales1-svr)(PORT=1521))
(ADDRESS=(PROTOCOL=tcp)(HOST=sales2-svr)(PORT=1521)))
(CONNECT_DATA=(SERVICE_NAME=sales.us.example.com))
Just beware you will also need root privileges. With default setting Linux kernel starts sending keepalive packets after 2 hours of inactivity. So you also have to change tcp_keepalive_time and tcp_keepalive_intvl in /etc/sysctl.conf. This is global server side settings and Oracle can not yet set keepalive interval for a single TCP connection.
One more comment: I recall there is some function called OCIPing.
This one can be used for testing too. But I'm not sure how to distinguish long running queries from dead server situation.
I'm using MongoDBs on three different computers only accessible by IPV6.
I'm able to connect to those DBs using php5 driver, command line interface (with the option --ipv6) and an UI app called "MongoHUB".
The only driver unable to connect thru IPV6 is the ruby one.
Any tip using it, for example, does exist an option when creating a MongoClient by uri stating the address is an ipv6 one, as with command line ?
The MongoDB Ruby driver doesn't support IPv6 yet (just an oversight/no one had requested it), but it will be fully supported in our next release.
Add yourself as a watcher to this ticket here to follow the progress:
https://jira.mongodb.org/browse/RUBY-700
I am trying to find somw Windows based tools that can help me validate TCP and UDP connection on remote machines.
My Problem (just one use case):
At work, I manage many clustered servers that I run load tests against. In order to get a rich test, I use Jmeter-Plugins which provides a Server agent that opens a TCP socket on port 4444 on a target remote machine: http://code.google.com/p/jmeter-plugins/wiki/PerfMonAgent
There are many times when I setup a new load test farm, that either the network, or the server configuration, or the ServerAgent itself can have issues and thus not allowing a Load test client to access that TCP connection.
The issue I have is that I dont know what part of the system is broken.
What I think I need:
I would like to know how I can open a TCP (not HTTP with cUrl), connection to a remote server to validate that the network allows the connection, as well as the Server firewall allows the given TCP connection to be accessed remotely.
What I have looked:
These are some of the tools I have looked at so far:
Nmap http://nmap.org
Ncat http://sourceforge.net/projects/nmap-ncat/
TCP/IP Builder http://www.drk.com.ar
Zenmap 6.01 and nmap might do the job I want, but some machines where not accessible to Zenmap when I know 100% that the server was accessible via HTTP, so that was strange.
I have looked at many tools and either they:
Dont allow remote connections
Dont seem to want to connect to a TCP socket
Or I dont understand the tools to accomplish the validation I stated above.
I would greatly appreciate all comment and suggestions to help with this re-occurring problem I face.
Mick,
Firebind.com can do what you'd like to do. Firebind is an Internet based server that can listen on any of the 65535 UDP or TCP ports. It uses a java based client to send traffic to and from the server from your machine.
Carl
www.firebind.com
If I create a c++ server/client application, the port I used to communicate does it need to be open on the router of the server and client machine
Or what other approach could I take? the client computer needs to receive information from the server but I am not able to have any ports opened because it is on a school network....
[edit]
Hmm My setup is a php page running on a server say when I press hello, the server makes a ssh connection through php and sends shell commands to the machine. The server is running off of a school server which I do have ssh access to and run all my things from there. The client computer will be my pc running off of the school wifi which is not connected to the server. The server will try to make a ssh connection to the public ip of my computer running off of the school wifi(no ports open/can ssh out but no ssh in). Will these methods you mention make this possible, in particular the connect.c since I can't run putty off of the server, and the connect.c I could call from the php.
The choice of language is highly irrelevant here.
There don't need to be ports 'open' on any router, unless your traffic must pass through it. On normal peer hosts in the same network (or subnet) there would hardly be any firewall policy, not even in schools.
Technically it is possible for the switch to block peer-2-peer traffic (meaning traffic not destined to the outgoing gateway), but that is not very usual.
Of course, if the school doesn't allow outbound (WAN) traffic on most ports, tough luck, and they're absolutely right :)
You can look at
ssh (with tunnels -L, -D and -R options, perhaps -o GatewayPorts on)
stunnel
connect.c
http-tunnel
All very readily googled
To establish a TCP/IP connection, only the server port needs to be accessible by the client. The connection is full-duplex, therefore data can flow from the client to the server and vice-versa.
If you are using UDP for your application, which is a connection-less protocol, what happens depends heavily on the firewall or router and whether it performs connection tracking for your service or not.
Unless you provide some additional information on your service and the network setup on both the client and the server side, we cannot provide more concrete information.
I just re-installed Ubuntu server 10.04 and decided to change all of my default ports to get a little extra security. Everything works fine, except when I decided to change the FTP (ProFTPd) port from the standard 21 to 3521. No problems with firewalls or port forwarding. ProFTPd was restarted but when I am trying to connect to it,even though it does respond, it throws the client (FileZilla) into a "passive mode" and then never goes into listing a directory.
I don't really want to use the "passive mode" and I have it disabled in proftpd.conf, but nevertheless I can't seem to change the default port otherwise and make it working. It does seem to work fine on port 21. FYI, the proftpd was installed as a standalone daemon, if that matters somehow?
Ok, I think I figured this out after reading this page: link . It appears that most FTP connections are indeed "passive" and the problem with "active" connections comes from the use of firewalls on the client side since FTP server is initiating an outgoing "data" connection to the client on some random port. In passive mode the client initiates both "command" and "data" connections to the server and hence the firewall isn't a problem, but you should specify which "passive" ports to use on the server. I enabled 3520 and 3521 PassivePorts and it's now working
FTP Active Mode by definition requires the server to initiate its outgoing connections from port L-1. Does your firewall allow outgoing connections from port 3520 as well?
From the FTP RFC:
3.2. ESTABLISHING DATA CONNECTIONS
The mechanics of transferring data consists of setting up the data
connection to the appropriate ports and choosing the parameters
for transfer. Both the user and the server-DTPs have a default
data port. The user-process default data port is the same as the
control connection port (i.e., U). The server-process default
data port is the port adjacent to the control connection port
(i.e., L-1).
...
3.3. DATA CONNECTION MANAGEMENT
Default Data Connection Ports: All FTP implementations must
support use of the default data connection ports, and only the
User-PI may initiate the use of non-default ports.
Negotiating Non-Default Data Ports: The User-PI may specify a
non-default user side data port with the PORT command. The
User-PI may request the server side to identify a non-default
server side data port with the PASV command. Since a connection
is defined by the pair of addresses, either of these actions is
enough to get a different data connection, still it is permitted
to do both commands to use new ports on both ends of the data
connection.
You might wish to take the opportunity to change your users to SFTP, a much nicer protocol.