Connection to Redis Servier via StackExchange.Redis

Question

I try to make a test project using the Redis Server, installed on a Linux Ubuntu Virtual Machine, via a Virtual Box.

The Linux machine is linked with the local network via the Virtual Box's Bridged Adapter, the Virtual Box running on my development Windows 7 Machine.

The Linux Machine is a new one, just created, I did the

sudo ufw enable

and then restarted the redis server (on linux).

Now here is my try from Windows

C:\Users\my-user>nmap -p 6379 10.14.30.51
Starting Nmap 7.70 ( https://nmap.org ) at ...
Nmap scan report for 10.14.30.51
Host is up (0.0010s latency).

PORT     STATE    SERVICE
6379/tcp filtered redis
MAC Address: 08:00:27:98:94:49 (Oracle VirtualBox virtual NIC)

I created a new .NET MVC project with my Visual Studio 2017, and here is the controller's code:

using StackExchange.Redis;
using System.Web.Mvc;

namespace RedisClient.Controllers
{
    public class HomeController : Controller
    {
        public struct Server {
            public const string IP = "10.14.30.51";
            public const int Port = 6379;
        }

        public ActionResult Index() { return View(); }

        public ActionResult About()
        {            
            ConnectionMultiplexer redis = 
                ConnectionMultiplexer.Connect($"{Server.IP}:{Server.Port}"); 

            IDatabase db = redis.GetDatabase();
            string value = "abcdefg";
            db.StringSet("mykey", value);
            value = db.StringGet("mykey");

            ViewBag.Message = $"The value is '{value}'";

            return View();
        }

        public ActionResult Contact() { return View(); }
    }
}

So, when I click on the "About" link I obtain the following error on the .Connect line

It was not possible to connect to the redis server(s). UnableToConnect on 10.14.30.51:6379/Interactive, Initializing/NotStarted, last: NONE, origin: BeginConnectAsync, outstanding: 0, last-read: 0s ago, last-write: 0s ago, keep-alive: 60s, state: Connecting, mgr: 10 of 10 available, last-heartbeat: never, global: 0s ago, v: 2.0.601.3402

--EDIT

The output of

var log = new StringWriter();

ConnectionMultiplexer redis = ConnectionMultiplexer.Connect(
    $"{Server.IP}:{Server.Port},abortConnect=False", log);
var logOutput = log.ToString();

is the following:

10.14.30.51:6379,abortConnect=False

Connecting 10.14.30.51:6379/Interactive...
BeginConnect: 10.14.30.51:6379
1 unique nodes specified
Requesting tie-break from 10.14.30.51:6379 > __Booksleeve_TieBreak...
Allowing endpoints 00:00:05 to respond...
Awaiting task completion, IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=1,Free=8190,Min=4,Max=8191)
Not all tasks completed cleanly (from ReconfigureAsync#1524, timeout 5000ms), IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=4,Free=8187,Min=4,Max=8191)
10.14.30.51:6379 did not respond
Waiting for tiebreakers...
Awaiting task completion, IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=4,Free=8187,Min=4,Max=8191)
connection failed: 10.14.30.51:6379 (Subscription, UnableToConnect): UnableToConnect on 10.14.30.51:6379/Subscription, Initializing/NotStarted, last: NONE, origin: BeginConnectAsync, outstanding: 0, last-read: 5s ago, last-write: 5s ago, keep-alive: 60s, state: Connecting, mgr: 10 of 10 available, last-heartbeat: never, global: 0s ago, v: 2.0.601.3402
connection failed: 10.14.30.51:6379 (Interactive, UnableToConnect): UnableToConnect on 10.14.30.51:6379/Interactive, Initializing/NotStarted, last: NONE, origin: BeginConnectAsync, outstanding: 0, last-read: 5s ago, last-write: 5s ago, keep-alive: 60s, state: Connecting, mgr: 10 of 10 available, last-heartbeat: never, global: 0s ago, v: 2.0.601.3402
Finished awaiting tasks, IOCP: (Busy=2,Free=998,Min=4,Max=1000), WORKER: (Busy=4,Free=8187,Min=4,Max=8191)
10.14.30.51:6379 failed to nominate (Faulted)
> UnableToConnect on 10.14.30.51:6379/Interactive, Initializing/NotStarted, last: NONE, origin: BeginConnectAsync, outstanding: 0, last-read: 5s ago, last-write: 5s ago, keep-alive: 60s, state: Connecting, mgr: 10 of 10 available, last-heartbeat: never, global: 0s ago, v: 2.0.601.3402
No masters detected
10.14.30.51:6379: Standalone v2.0.0, master; keep-alive: 00:01:00; int: Connecting; sub: Connecting; not in use: DidNotRespond
10.14.30.51:6379: int ops=0, qu=0, qs=0, qc=0, wr=0, socks=2; sub ops=0, qu=0, qs=0, qc=0, wr=0, socks=2
Circular op-count snapshot; int: 0 (0,00 ops/s; spans 10s); sub: 0 (0,00 ops/s; spans 10s)
Sync timeouts: 0; async timeouts: 0; fire and forget: 0; last heartbeat: -1s ago
resetting failing connections to retry...
retrying; attempts left: 2...
1 unique nodes specified
Requesting tie-break from 10.14.30.51:6379 > __Booksleeve_TieBreak...
Allowing endpoints 00:00:05 to respond...
Awaiting task completion, IOCP: (Busy=1,Free=999,Min=4,Max=1000), WORKER: (Busy=2,Free=8189,Min=4,Max=8191)
Not all tasks completed cleanly (from ReconfigureAsync#1524, timeout 5000ms), IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=2,Free=8189,Min=4,Max=8191)
10.14.30.51:6379 did not respond
Waiting for tiebreakers...
Awaiting task completion, IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=2,Free=8189,Min=4,Max=8191)
Not all tasks completed cleanly (from NominatePreferredMaster#1761, timeout 50ms), IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=2,Free=8189,Min=4,Max=8191)
10.14.30.51:6379 failed to nominate (WaitingForActivation)
No masters detected
10.14.30.51:6379: Standalone v2.0.0, master; keep-alive: 00:01:00; int: Disconnected; sub: Disconnected; not in use: DidNotRespond
10.14.30.51:6379: int ops=0, qu=0, qs=0, qc=0, wr=0, socks=2; sub ops=0, qu=0, qs=0, qc=0, wr=0, socks=2
Circular op-count snapshot; int: 0 (0,00 ops/s; spans 10s); sub: 0 (0,00 ops/s; spans 10s)
Sync timeouts: 0; async timeouts: 0; fire and forget: 0; last heartbeat: -1s ago
resetting failing connections to retry...
retrying; attempts left: 1...
1 unique nodes specified
Requesting tie-break from 10.14.30.51:6379 > __Booksleeve_TieBreak...
Allowing endpoints 00:00:05 to respond...
Awaiting task completion, IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=2,Free=8189,Min=4,Max=8191)
Not all tasks completed cleanly (from ReconfigureAsync#1524, timeout 5000ms), IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=5,Free=8186,Min=4,Max=8191)
10.14.30.51:6379 did not respond
Waiting for tiebreakers...
Awaiting task completion, IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=5,Free=8186,Min=4,Max=8191)
Finished awaiting tasks, IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=2,Free=8189,Min=4,Max=8191)
10.14.30.51:6379 failed to nominate (Faulted)
> UnableToConnect on 10.14.30.51:6379/Interactive, Initializing/NotStarted, last: NONE, origin: BeginConnectAsync, outstanding: 0, last-read: 5s ago, last-write: 5s ago, keep-alive: 60s, state: Connecting, mgr: 10 of 10 available, last-heartbeat: never, global: 10s ago, v: 2.0.601.3402
No masters detected
10.14.30.51:6379: Standalone v2.0.0, master; keep-alive: 00:01:00; int: Disconnected; sub: Disconnected; not in use: DidNotRespond
10.14.30.51:6379: int ops=0, qu=0, qs=0, qc=0, wr=0, socks=3; sub ops=0, qu=0, qs=0, qc=0, wr=0, socks=3
Circular op-count snapshot; int: 0 (0,00 ops/s; spans 10s); sub: 0 (0,00 ops/s; spans 10s)
Sync timeouts: 0; async timeouts: 0; fire and forget: 0; last heartbeat: -1s ago
Starting heartbeat...

==References

In my .csproj file I have, among others

<Reference Include="System.Buffers, Version=4.0.3.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
  <HintPath>..\packages\System.Buffers.4.5.0\lib\netstandard2.0\System.Buffers.dll</HintPath>
</Reference>
...
<Reference Include="System.Runtime.CompilerServices.Unsafe, Version=4.0.4.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
  <HintPath>..\packages\System.Runtime.CompilerServices.Unsafe.4.5.2\lib\netstandard2.0\System.Runtime.CompilerServices.Unsafe.dll</HintPath>
</Reference>
...
<Reference Include="System.Numerics.Vectors, Version=4.1.4.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
  <HintPath>..\packages\System.Numerics.Vectors.4.5.0\lib\net46\System.Numerics.Vectors.dll</HintPath>
</Reference>

The related SuperUser question with another details is here.

Windows:

Linux:

Answer 1

Thank to this SF answer I were able to make communicate the host Windows and virtual Linux machines.

The steps I did:

On the Redis Server (Linux) machine:

1) ss -tlnp 'sport == :6379' if you find 127.0.0.1 or ::1 in these lines, you've should edit the redis.config file, comment the bind 127.0.0.1 ::1 in the config file (if not already), and don't forget to restart redis after changing of the configuration.
If you see something like 0.0.0.0:6379, follow the next step.

2) Check the protected mode of Redis in the same config file, if is enabled and you want to keep it, you can use requirepass <yourConnectionPassToUseOnClientConnectionString> in the Redis config file.

3) Check your client IP address (in my case the windows client computer). Add it to the Linux iptables:

iptables -A INPUT --src <clientIpAddress> -p tcp --dport 6379 -j ACCEPT

3') in order to make this added entry persistent, see how to save the iptables state here.

On the Client (Windows) machine:

4) use the above password in the connection string to connect to the Linux Redis Server

ConnectionMultiplexer redis = 
  ConnectionMultiplexer.Connect($"{Server.IP}:{Server.Port},resolvedns=1,abortConnect=False,password={Server.Password}");

5*) optionally, you can add the you can get Windows builds from choco (install it on Windows), to test the connection from the client Windows, using cmd

redis-cli -h <LinuxServerIP> -p 6379 ping