I'm curious if it is possible to map a UNIX socket on to an INET socket. The situation is simply that I'd like to connect to a MySQL server. Unfortunately it has INET sockets disabled and therefore I can only connect with UNIX sockets. The tools I'm using/writing have to connect on an INET socket, so I'm trying to see if I can map one on to the other.
It took a fair amount of searching but I did find socat, which purportedly does what I'm looking for. I was wondering if anyone has any suggestions on how to accomplish this. The command-line I've been using (with partial success) is:
socat -v UNIX-CONNECT:/var/lib/mysql/mysql.sock TCP-LISTEN:6666,reuseaddr
Now I can make connections and talk to the server. Unfortunately any attempts at making multiple connections fail as I need to use the fork option but this option seems to render the connections nonfunctional.
I know I can tackle the issue with Perl (my preferred language), but I'd rather avoid writing the entire implementation myself. I familiar with the IO::Socket libraries, I am simply hoping anyone has experience doing this sort of thing. Open to suggestions/ideas.
Thanks.
Reverse the order of your arguments to socat, and it works.
socat -v tcp-l:6666,reuseaddr,fork unix:/var/lib/mysql/mysql.sock
This instructs socat to
Listen on TCP port 6666 (with SO_REUSEADDR)
Wait to accept a connection
When a connection is made, fork. In the child, continue the steps below. In the parent, go to 2.
Open a UNIX domain connection to the /var/lib/mysql/mysql.sock socket.
Transfer data between the two endpoints, then exit.
Writing it the other way around
socat -v unix:/var/lib/mysql/mysql.sock tcp-l:6666,reuseaddr,fork
doesn't work, because this instructs socat to
Open a UNIX domain connection to the /var/lib/mysql/mysql.sock socket.
Listen on TCP port 6666 (with SO_REUSEADDR)
Wait to accept a connection
When a connection is made, spawn a worker child to transfer data between the two addresses.
The parent continues to accept connections on the second address, but no longer has the first address available: it was given to the first child. So nothing useful can be done from this point on.
Yes, you can do this in Perl.
Look at perlipc, IO::Select, IO::Socket and Beej's Guide to Network Programming.
You might want to consider doing it in POE - it's asynchronous library for dealing with events, so it looks like great for the task.
It is not 100% relevant, but I use POE to write proxy between stateless protocol (HTTP) and statefull protocol (telnet session, and more specifically - MUD session), and it was rather simple - You can check the code in here: http://www.depesz.com/index.php/2009/04/08/learning-poe-http-2-mud-proxy/.
In the comments somebody also suggested Coro/AnyEvent - I haven't played with it yet, but you might want to check it.
Related
I'm a total beginner to MySQL, I'm more of a firmware specialist. I'm working on an application where I will be getting GPS coordinates from a microcontroller + cellular device and I would like some way to store the coordinates and do processing on them. I figured a database hosted on a server made the most sense, which is what has brought me to MySQL.
Basically, I'm wondering what the basic protocol is for sending data to a MySQL server over an internet connection (my device has data). Like how do I connect to the server and publish data to it?
I'm experienced with MQTT and I think I could do TCP as well but I'm looking for a protocol that is not super power-intensive and I can't use anything that requires an operating system, like a python script.
To be clear, I am NOT asking you to tell me every step for how this is done, but basically what protocol and what tools could I use? Anything you can tell me would be appreciated.
I was thinking that I could use the MySQL client C code to help write a driver that could allow me to connect to the server. I'm experienced with writing drivers and the microcontroller I'm using uses C.
You need no direct connection to the DB at all. Your cellular device should be able to establish tcp connection to the ipaddress/port and to send the byte-stream through the connection. It can be the dumb unidirectional protocol with losses.
You need some service that can listen on the other side, that can parse your byte-stream, can fetch the correct packets from it and then send the data to the database. Speaking frankly that service can even be written in linux shell:
nc -lk 1234 | collector.sh
where collector.sh is a script like that:
#!/bin/sh
while read LINE
do
# $LINE parsing and all the staff
mysql -e "INSERT INTO mygps.nmea (lat,lon,dtime) VALUES ($LAT, $LON, $DTIME);"
done <<< /dev/stdin
####
Sure it isn't a best solution but it was really helpful for me at the very beginning. Then you can proceed the gathered data in any desired way.
Build a simple server that communicates with whatever gathered data and then use the server so send the data to MySQL with the help of MySQL connector. Building part of the protocol will quite time consuming. - nbk
If you "can't use anything that requires an operating system" you need some middleware that can run the MySQL client driver to talk to the database, you will then use MQTT to pass data between your sensor and the middleware. If you don't want to write this middleware yourself, something like Node-RED might come handy.
You certainly can reimplement the driver for your MC, though I personally would not want to waste the time on something like this when I can assemble a solution from existing components. Database protocols are typically chatty, synchronous, and sensitive to network quality, and I wouldn't want to waste my MC cycles on that when I can make middleware do that asynchronously. - mustaccio
Simply "reverse ssh port forwarding"? That can be done, I think, with a single ssh command at one (or both) end of the connection. MySQL, by default, needs the client to connect on port 3306 to the server. - rick-james
introduction
when configuring elasticsearch I ran into a problem with binding the
listening interfaces.
somehow the documentation does not provide how to setup multiple network interfaces (network def and bind def)
problem description
my intention is to setup the network.bind_host as _eth1:ipv4_ and _local_
even when trying to setup the bind_host as _local_ only,
the elastic search port 9200 is still only reachable by eth1 (of course i have restarted the server)
solutions tried
i have tested the firewall configuration by setting up a netcat server and this one works perfectly for that port
so this results in 2 Questions:
how to configure multiple nics? (whats the notation?)
would i require to change the network.publish_host ?!
.
any other pointers?
current configuration:
network.bind_host: _eth1:ipv4_
network.publish_host: _eth1:ipv4_
network.host: _eth1:ipv4_
also tested configuration:
network.bind_host: _local_
network.publish_host: _eth1:ipv4_
network.host: _local_
PS:
afaik the publish_host is the nic for the inter-server communication
Using a YAML list for the desired property:
network.bind_host:
- _local_
- _en0:ipv4_
If I understand this answer correctly, publish_host should be _eth1:ipv4_. Your publish_host has to be a one of the interfaces to which elasticsearch binds via the bind_host property.
The above linked answer is actually great, so I have to cite it here:
"bind_host" is the host that an Elasticsearch node uses in the socket
bind call when starting the network. Due to socket programming model,
you can "bind" to an address. By referencing an "address", the socket
allows access to one or all underlying network devices. There are
several addresses with predefined semantics, e.g. 0.0.0.0 is reserved
for "bind to all network devices". So the "bind_host" address does not
necessarily reflect a single unique address.
"publish_host" must be a single unique network address. It is used for
connect calls by other nodes, not for socket bind call by the node
itself. By using "publish_host" all nodes and clients can be sure they
can connect to this node. Declaring this single unique address to the
outside can be interpreted as "publishing", so it is called
"publish_host".
You can not set "bind_host" and "publish_host" to arbitrary values,
the values must adhere to the underlying socket model.
I've been running my Google Compute VM for literally 1 day, and I was hacked, by this IP: http://www.infobyip.com/ip-121.8.187.25.html
I'm trying to understand what I can do next (user connected via ssh, root password was changed), to avoid these types of attacks (and to understand more than what /var/log/auth.log is telling me) ?
I assume you deleted the instance already, right ? from Developers console.
As suggested, always use ssh rsa keys to connect to your instance, instead of passwords. Additionally, depending on where you want access from, you can only allow certain IPs through the firewall. Configuring the firewall along with iptables, gives you better security.
You may also want to take a look at sshguard. Sshguard will add iptables rules automatically when it detects a number of failed connection attempts.
Just to make sure, please change the default port 22 in /etc/ssh/sshd_config to something else.
I saw the following statement on StackOverflow and was wondering about its meaning:
If you connect via 'localhost', the connection will automatically be established via the MySQL socket, which is really cheap anyways.
The discussion thread was pretty old, so I didn't want to comment on it.
Basically what I understand is, that using 'localhost' when connecting to your mysql database has certain advantages - such as "automatically established connections via MySQL socket". What does that mean exactly?
Currently I'm using
mysql_connect("73.21.24.201", [...]);
(changed to a random IP Address)
Does it make any difference? Can I change it to "localhost" without having to worry about it? (The mysql server is obviously on the same server/ip address as my website/application)
When you connect to 'localhost' you'll connect using a Unix socket, which is just a communications channel for the local processes to use. The big advantage of this is that you can disable networking completely in MySQL, and negate any processing overhead and security risks that go along with that.
When MySQL starts, it creates a socket file (typically at a place like /var/lib/mysql/mysql.sock) that your client program needs to be able to find. On a typical PHP (you didn't say, but I'm assuming) setup, it should know where to find this socket. If not, check /etc/my.cnf and /etc/php.ini to make sure the values match.
And finally, if that is PHP, stop using mysql_*() functions in PHP right now! They have been deprecated for years and are inefficient and insecure.
I want to send emails using gmail's smtp with the PHP script posted below using Swiftmailer. Now this works fine on my own webserver. But when I used it on the webserver of the people I'm creating this for, I get an exception:
Fatal error: Uncaught exception 'Swift_TransportException' with message 'Connection could not be established with host smtp.gmail.com [Connection timed out #110]' in ...
What could be the problem?
I'm assuming its got to do with the difference in server settings, because the code works on my own webserver. I've checked with phpinfo() the following:
- Registered Stream Socket Transports tcp, udp, unix, udg, ssl, sslv3, sslv2, tls
- OpenSSL support enabled
- OpenSSL Library Version OpenSSL 1.0.1e-fips 11 Feb 2013
This is my PHP code:
$emailname = MY_GMAIL_ACCOUNT_USERNAME;
$emailpass = MY_GMAIL_ACCOUNT_PASSWORD;
$transport = Swift_SmtpTransport::newInstance('smtp.gmail.com', 465, "ssl")
->setUsername($emailname)
->setPassword($emailpass);
$mailer = Swift_Mailer::newInstance($transport);
$message = Swift_Message::newInstance($emailtitle)
->setFrom(array($emailname.'#gmail.com' => $emailsender))
->setTo(array($emailrecp))
->setBody($emailbody,'text/html');
$result = $mailer->send($message);
I had the same issue on a Digital Ocean server. Turns out they're blocking SMTP by default on IPv6. Here's the fix:
nano /etc/gai.conf
precedence ::ffff:0:0/96 100
as per:
https://www.digitalocean.com/community/questions/outgoing-connections-on-port-25-587-143-blocked-over-ipv6
My easy solution to avoid the problem of dynamic IP (every time i ping smtp.gmail.com I see a slight difference in the last 3digit chunk), is to simply use php built-in gethostbyname() to read the IP in real-time.
$smtp_host_ip = gethostbyname('smtp.gmail.com');
$transport = Swift_SmtpTransport::newInstance($smtp_host_ip,465,'ssl')
->setUsername('username')->setPassword('pwd');
Im not advanced in php and streams but it seems that IPv6 DNS resolution depends on the router and/or ISPs. I changed my provider, got a new router and the smtp connection always timed out.
To use IPv6 you should either add your own IPv6 or force stream_context_create to use IPv4. You can call setSourceIp() on a swiftmailer object or directly change the Swift_SmtpTransport class (i.e. in the constructor).
Use IPv6:
// replace IP with your own IPv6
$this->setSourceIp('2aaa:8a8:fc0:230:fds:4fd:faa:24ae');
Use IPv4 (mentioned at https://github.com/phergie/phergie/issues/195):
$this->setSourceIp('0.0.0.0');
just add
74.125.130.108 smtp.gmail.com
to server's hosts file
I've just been doing battle with exactly the same problem. Mine worked locally too, but as soon as it got on a real server ... no. It just would not work even though all the settings were the same.
After many hours, I've think I've found out why.
What seems to happen is that on a server with IPv4 and IPv6 support, IPv6 takes precedence. Which makes sense, given that it's newer. But in the case of smtp.gmail.com, it appears to only listen on IPv4. So when the server resolved smtp.gmail.com, it got its IPv6 address back and so PHP tried to connect to it. That eventually gives up with a "Connection timed out" exception. Now you would think that fsockopen, presumably, would detect the connection wasn't working and so try IPv4, but seemingly it doesn't.
If you find out what smtp.gmail.com's IPv4 address is (ping smtp.gmail.com) and simply put that IP in place of the hostname in the code - it works :)
It's not ideal coding in an IP address - given that Google could change it at any minute - but at least you will get some emails sent
The answer for me was that my server was blocking the outbound connection. It could be your firewall or your host.
The way to test this is to try connecting yourself. I used telnet on two different machines to compare and it became obvious that this was my issue. There may be a way to test this with curl directly.