I have my MySQL database server on Server 1. I want to have my Rails apps on two other servers - say A and B to be able to connect to this Server 1. What's the best way to do this?
In the my.cnf file it appears I can use the bind-address to bind to one and only one IP address. I can't specify the IP addresses of both A and B in my.cnf.
On the other hand, if I comment skip-networking, the gates are wide open.
Is there a golden mean? What are you folks doing to allow a DB server to listen to requests from multiple app servers and still stay secure?
If MySQL is running on Linux:
I am very biased towards using iptables (a.k.a. netfilter, the Linux firewall) to control incoming traffic to various ports. It's simple to use and very robust.
iptables -A INPUT -p tcp -s server1address/32 --dport 3306 -j ACCEPT
iptables -A INPUT -p tcp -s server2address/32 --dport 3306 -j ACCEPT
iptables -A INPUT -p tcp --dport 3306 -j DROP
The bind address is the local IP address of the server, not the allowable client addresses. In your situation, you can provide the static address of your server (in place of localhost) or, if your IP might change, just comment it out.
Again, to clarify: the bind-address is the address on which the server listens for client connections (you could have multiple NICs, or multiple IP addresses, etc.). It is also possible to change the port you want mysql to listen to.
You will want to make sure you configure the root password if you haven't already:
mysql> SET PASSWORD FOR 'root'#'localhost' = PASSWORD('yourpassword');
You would then use other means to restrict access to MySql to something like the local network (i.e. your firewall).
More info about iptables:
The iptables commands above must either be inserted in the existing iptables tables, or else you must delete the existing stuff and start from scratch with the commands above.
Insertion is not hard, but it depends a little bit on the Linux distribution you use, so I'm not sure what to recommend.
To start from scratch, you need to Flush and eXpunge the existing tables first:
iptables -F
iptables -X
Then insert the iptables firewall rules that you need to use, following the model indicated in my previous answer.
Then save the iptables rules. This is again distribution-dependent. On most Red Hat derivatives (Red Hat, Fedora, CentOS), it's enough to run:
service iptables save
Voila, your custom rules are saved. If the iptables service is enabled (check with "chkconfig --list iptables", it must be ":on" on runlevels 3 and 5, depending on your situation, but it's safe to set it ":on" on both 3 and 5 in any case) then your rules will survive the reboot.
At any time, you can check the current running iptables rules. Here's a few commands that do that, with various levels of verbosity:
iptables -L
iptables -L -n
iptables -L -n -v
Without -n, it will try to lookup the domain names and display them instead of IP addresses - this may not be desirable if DNS is not working 100% perfect.
So that's why I almost always use -n.
-v means "verbose", a bit harder to read but it gives more information.
NOTE: If you start from scratch, other services running on that machine may not be protected by iptables anymore. Spend some time and figure out how to insert the MySQL rules in the existing tables. It's better for your system's security.
In addition to getting the bind address right you'll need to open the correct port, create or configure the users and some other details. This explains it pretty clearly.
A DB server will listen to an indefinite number of clients.
Each client Rails app identifies the DB server.
The DB server waits patiently for connections. It has no idea how many clients there are or where the connections come from.
Edit
"how do you securely configure the DB wrt what servers to accept requests from?"
That's what networks, firewalls and routers are for.
That's why the database requires credentials from the Rail apps.
Related
I have a simple chat app written in javascript(client and node server) with socket.io. Users are permanently connected to server. I need to test how my application behaves when connection with node-socket.io-server being dropped. I need to block socket.io connection for a few seconds and then allow my app to connect again. I need to do it using the browser, without stopping the server.
I know that chrome developer tools has a future of simulating offline mode but this future does not drops/blocks socket.io connections.
So, how can i drop socket.io connection for a few seconds using chrome browser?
It's possible to simulate disconnection using firewall rules on either the backend or the client side.
On the client side you need to drop all outbound packets to the server, for a few seconds
Example using iptables (will work on linux clients):
SERVER_IP="1.1.1.1"
# Append rule
iptables -A OUTPUT -d $SERVER_IP -j DROP
sleep 5
# Delete rule
iptables -D OUTPUT -d $SERVER_IP -j DROP
On the server side you need to drop all inbound packets from_the specific client, for a few seconds
Example using iptables (will work on linux clients):
CLIENT_PUBLIC_IP="2.2.2.2"
# Append rule
iptables -A INPUT -s $CLIENT_PUBLIC_IP -j DROP
sleep 5
# Delete rule
iptables -D INPUT -s $CLIENT_PUBLIC_IP -j DROP
I'm a beginner in both docker and mysql, and I use below command to run a mysql container
docker container run --publish 3306:3306 --name mysqlDB -d --env MYSQL_RANDOM_ROOT_PASSWORD=yes mysql
Now it run successfully and in order to grab the generated password, I run below command
docker container logs [containerID]
Within the logs I can find my GENERATED ROOT PASSWORD, but as I try to read the logs I noticed the below log
[System] [MY-011323] [Server] X Plugin ready for connections. Socket: '/var/run/mysqld/mysqlx.sock' bind-address: '::' port: 33060
May I know what is this means? Is there by any chance I opened a port 33060? And how do I verify it?
This seems to be a MySQL plugin that adds document-oriented APIs to MySQL. Here you can find some more info: https://www.percona.com/blog/2019/01/07/understanding-mysql-x-all-flavors/
That port number seems to be unrelated to your bindings, that's just adefault port number for that plugin.
Also, that port number is not exposed, so, there is nothing to fear, attack surface is still the same.
And if you want to disable that thing, here are the instructions: https://dev.mysql.com/doc/refman/8.0/en/x-plugin-disabling.html (command line option is probably your best bet -- considering docker environment).
To make sure port is not exposed you can run container and do docker ps, you'll see something like this:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
43dd96119ded lb_geo-api "/bin/sh -c 'exec sh…" 6 months ago Up 7 days 80/tcp, 0.0.0.0:4203->8080/tcp lb_geo-api_1_a86ebad528fc
Last column -- "PORTS" -- is the list of ports and their bindings on your host:
80/tcp -- port 80 can is exposed from inside container but not mapped to host port, so, nobody from outside can connect there
0.0.0.0:4203->8080/tcp -- port 8080 is exposed and is mapped to port 4203 on all network adapters, and it can be connected from outside
So, if there is no port 33060 in your output, or if it is there but not mapped -- you're safe. In any case only you can map it when you start the container, so, if you did not do that, then it is not mapped.
I was surprised by a MySQL log entry equivalent to yours, #Isaac, which led me to your question, although I'm not working with Docker. Here is what I think I've learned and what I've done.
MySQL's "X plugin" extends MySQL to be able to function as a document store. See MySQL manual section on server plugins, manual section on document store features, and April 2018 document store availability announcement.
By default, for its X plugin features, MySQL listens on port 33060, bound to all IP addresses. See manual section on X plugin options and system variables (indicating default values for "mysqlx_port" and "mysqlx_bind_address"), and X plugin option and variable reference. For its traditional features, MySQL still uses port 3306 by default.
I believe the default X plugin port and network address are what are reflected in the log entry you posted. In particular, I believe the excerpt X Plugin ... bind-address: '::' indicates MySQL's default wildcard ip address binding for X plugin connections.
If you'd like to use the X plugin features but refrain from listening to all IP addresses for them, you can specify the address(es) to which it listens for TCP/IP connections with the mysqlx_bind_address option. The command line format would be
--mysqlx-bind-address=addr
Alternatively, you could set that system variable in a MySQL option file, like this for example:
[mysqld]
<... other mysqld option group settings>
mysqlx_bind_address = 127.0.0.1
The MySQL manual provides helpful general information about specifying options on the command line or in an option file. Here is some information about setting MySQL options in a Docker container, although I have never tried it.
It seems there are distinct settings for the network addresses listened to by MySQL's X-plugin-enabled features and MySQL's traditional features. You set the network address(es) for the traditional features with the bind_address option. So if you want to limit both sets of features to listening for TCP/IP connections from localhost, you could, for example, put this in your MySQL options file, which is what I've just tried in mine:
[mysqld]
bind_address = 127.0.0.1
mysqlx_bind_address = 127.0.0.1
In contrast, it appears, you could set a single system variable -- skip_networking -- to permit only local, non-TCP/IP connections (e.g., Unix sockets, or Windows named pipes or shared memory) for both traditional and X Plugin features.
If you don't want to use the X plugin features at all, you could disable them as #alx suggested.
To verify which network addresses and ports MySQL is listening on, you have a variety of options. In my non-docker Linux environment, I found
netstat -l | grep tcp
and
sudo lsof -i | grep mysql
helpful.
You have published your port. That --publish 3306:3306 actually publishes your container port to host port and now your host port 3306 is occupied by mysql. If you do not want that you can just remove --published 3306:3306 and container port will not be bound to host port.
My MASTER mysql server is on a local network, and I have a new slave which is remote (i.e. on the internet). As MASTER does not have an accessible IP, I gathered from the docs that I should establish a reverse tunnel. I execute this:
ssh -f -N -T -R 7777:localhost:3306 user#slave.slave.com
on the MASTER. The connection seems to work - I can go to the slave and connect
with mysql to the MASTER without problem. For some reason though, replication does
not start. MASTER is already replicating to two other slaves without problems - seems the configuration is correct there.
I initiated replication on the slave as:
CHANGE MASTER TO MASTER_HOST='127.0.0.1',
MASTER_PORT=7777,
MASTER_USER='my_repl',
MASTER_PASSWORD='xxxxx',
MASTER_LOG_FILE='mysql-bin.nnnnn',
MASTER_LOG_POS=mm;
SLAVE STATUS reports mysql trying to connect to the remote, but never succeeding:
error connecting to master 'my_repl#127.0.0.1:7777' - retry-time: 60 retries: 86400
Can anyone suggest how to diagnose this problem?
BTW: OS is Linux.
My apologies... I didn't realize I had to define a new user with 127.0.0.1 as
IP.
So, 'intranet' connections use
replication_user#machine_name
as id, the connection which comes through the reverse tunnel uses
replication_user#127.0.0.1
as id. Both have to be declared to mysql separately. The rest of the info in the original message is valid - maybe this helps someone...
Greetings,
John
PS: Forgot to mention - I debugged this remotely (both MASTER and SLAVE are remote to me) using tcpdump:
tcpdump -i lo 'tcp port 7777'
on the SLAVE side, and
tcpdump -i lo 'tcp port 3306'
on the MASTER (of course that would not be very useful when there is much traffic).
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I opened a ssh tunnel as described in this post: Zend_Db: How to connect to a MySQL database over SSH tunnel?
But now I don't know what I actually did. Does this command affect anything on the server?
And how do I close this tunnel, because now I can't use my local mysql properly.
I use OSX Lion and the server runs on Ubuntu 11.10.
Assuming you ran this command: ssh -f user#mysql-server.com -L 3306:mysql-server.com:3306 -N as described in the post you linked.
A breakdown of the command:
ssh: that's pretty self-explanatory. Invokes ssh.
-f: (From the man ssh page)
Requests ssh to go to background just before command execution.
This is useful if ssh is going to ask for passwords or
passphrases, but the user wants it in the background.
Essentially, send ssh to background once you've entered any passwords to establish the connection; it gives the shell prompt back to you at localhost rather than logging you in to remote-host.
user#mysql-server.com: the remote server you'd like to log into.
-L 3306:mysql-server.com:3306: This is the interesting bit. -L (from the man ssh page):
[bind_address:]port:host:hostport
Specifies that the given port on the local (client) host is to be
forwarded to the given host and port on the remote side.
So -L 3306:mysql-server.com:3306 binds the local port 3306 to the remote port 3306 on host mysql-server.com.
When you connect to local port 3306, the connection is forwarded over the secure channel to mysql-server.com. The remote host, mysql-server.com then connects to mysql-server.com on port 3306.
-N: don't execute a command. This is useful for "just forwarding ports" (quoting the man page).
Does this command affect anything on the server?
Yes, it establishes a connection between localhost and mysql-server.com on port 3306.
And how do I close this tunnel...
If you've used -f, you'll notice that the ssh process you've opened heads into the background. The nicer method of closing it is to run ps aux | grep 3306, find the pid of the ssh -f ... -L 3306:mysql-server.com:3306 -N, and kill <pid>. (Or maybe kill -9 <pid>; I forget if just kill works). That has the beautiful benefit of not killing all your other ssh connections; if you've got more than one, re-establishing them can be a slight ... pain.
... because now I can't use my local mysql properly.
This is because you've effectively "captured" the local mysql process and forwarded any traffic that attempts to connect to it, off to the remote mysql process. A much nicer solution would be to not use local port 3306 in the port-forward. Use something that's not used, like 33060. (Higher numbers are generally less used; it's pretty common to port-forward a combination like this: "2525->25", "8080->80", "33060->3306" or similar. Makes remembering slightly easier).
So, if you used ssh -f user#mysql-server.com -L 33060:mysql-server.com:3306 -N, you'd then point your Zend connect-to-mysql function to localhost on port 33060, which would connect to mysql-server.com on port 3306. You can obviously still connect to localhost on port 3306, so you can still use the local mysql server.
This will kill all ssh sessions that you have open from the terminal.
sudo killall ssh
Note: adding as answer since comments don't support code blocks.
In my opinion it is better to NOT use -f and instead just background the process as normal with &. That will give you the exact pid you need to kill:
ssh -N -L1234:other:1234 server &
pid=$!
echo "waiting a few seconds to establish tunnel..."
sleep 5
... do yer stuff... launch mysql workbench whatever
echo "killing ssh tunnel $pid"
kill $pid
Or better yet, just create this as a wrapper script:
# backend-tunnel <your cmd line, possibly 'bash'>
ssh -N -L1234:other:1234 server &
pid=$!
echo "waiting a few seconds to establish tunnel..."
sleep 5
"$#"
echo "killing ssh tunnel $pid"
kill $pid
backend-tunnel mysql-workbench
backend-tunnel bash
To list active connections we do:
show processlist;
What to do to list old closed connections?
The simple answer is that there's nothing provided by MySQL to list old connections. But you could capture the data flowing between your web front end and your database:
tcpdump -i eth0 -s 0 -w /tmp/mysql.cap tcp port 3306
run your PHP, have it fail, stop the capture and use Wireshark to see exactly what was going on.
I could obtain this nice answer from serverfault.