I'm trying to connect to a WebSocket server (PHP / Wrench) running on my webserver.
The configuration of the server looks like this:
$server = new \Wrench\Server("wss://localhost:8443");
$server->registerApplication('app',
new \Wrench\Application\EchoApplication());
$server->run();
I'm using port 8443 because I can't use 80 or 443 (Permission denied). The domain uses HTTPS so I have to use the wss: protocol.
I have no problem connecting to the PHP server when I run the script on my local machine (I just have to replace wss: by ws:).
When I run the server via SSH on my remote webserver, it seems to run correctly, but trying to connect to it via JS with the following call doesn't work:
var ws = new WebSocket("wss://dev.mydomain.net:8443/app");
I get an "Error in connection establishment: net::ERR_CONNECTION_REFUSED."
On my webserver panel control, the 8443 port (TCP) is open (in and out). When the PHP server is running, the command netstat -a | grep 8443 gives the following output, which I think should confirm it's open:
tcp 0 0 localhost:8443 *:* LISTEN
Is there an obvious detail I'm missing here?
I finally found a solution: instead of setting the URI of the server to localhost, I had to use 0.0.0.0. Now it works perfectly when I'm using HTTP (there's another problem when using HTTPS, but at least I have more information at this point).
Related
I wrote a simple http server in Go language as below:
http.ListenAndServe(":8888", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("hello"))
}))
When I test it on certain machine runs Windows 7, I found client can't connect to the server.
telnet 127.0.0.1 8888
connecting 127.0.0.1… can't open connection to the host. on port 8888: connect failed. (I translate it from Chinese.)
Then I got the results of other test case:
ping localhost and 127.0.0.1, successful.
telnet localhost 8888, successful.
telnet ::1 8888, successful.
netstat -ano | find "8888", the server has listened 0.0.0.0:8888 and :::8888.
Check the hosts file of OS, it's default configuration (nothing else).
Check the Network Adapter, it doesn't open IPV6 adapter.
The machine is in domain network.
The IP Security Policy is an empty list.
When I opened the MMC(Microsoft Management Console), I got a warning like this:
message box
It mean's:
Can't find resource "$(string.SiteDiscoveryEnableWMI)" (references in property displayName)
. File C:\windows\PolicyDefinitions\inetres.admx, line 64620, row 235
Anyone can tell me what's going on?
If XAMPP is running in your machine, the local server sometimes uses 127.0.0.1 as the default.
This could be the reason that ping localhost is working but telnet is not.
Otherwise check other network services or localservers you have running for any conflicts.
Cheers!
I am building simple webpage.
I could run on my local host.
I made ec2 instance, I opened ports 22, 8000.
I could connect with ssh and run server for webpage,
but I get this error
this is my github address that contain the code.
enter link description herehttps://github.com/MoreNiceJay/django2
In your security group rules, open port 80
This is the standard port for http traffic
Other things to check: login to the host with ssh and use netstat |grep LISTEN to see if there is a process listening on port 80
I have an EC2 instance which is running with the following security groups:
HTTP - TCP - 80 - 0.0.0.0/0
Custom UDP Rule - UDP - 1194 - 0.0.0.0/0
SSH - TCP - 22 - 0.0.0.0/0
Custom TCP Rule - TCP - 943 - 0.0.0.0/0
HTTPS - TCP - 443 - 0.0.0.0/0
However, when I try to access http://{PUBLIC_IP} or https://{PUBLIC_IP} in the browser, I get a "{IP} refused to connect" error. I'm new to AWS. Am I missing something here? What should I do to debug?
One way to debug this particular class of problem is to use netcat in order to determine where the problem lies.
If you run netcat against port 80 on the public IP address of your instance and just get a hang (no output at all), then most likely your security group isn't allowing traffic through. Here is an example from an EC2 instance that is in a security group that doesn't allow port 80 traffic inbound:
% nc -v 55.35.300.45 80
<just hangs>
Whereas if the security group is changed to allow port 80, but the EC2 instance doesn't have any process listening on port 80, you'll get the following:
% nc -v 55.35.300.45 80
nc: connectx to 52.38.300.43 port 80 (tcp) failed: Connection refused
Given that your browser gave you a similar "connection refused", most likely the problem is that there is no web server running on your instance. You can verify this by ssh'ing into the instance and seeing if you can connect to port 80 there:
ssh ec2-user#55.35.300.45
% nc -v localhost 80
nc: connect to localhost port 80 (tcp) failed: Connection refused
If you get something like the above, you're definitely not running a webserver.
I'm not sure if it's too late to help but I was stuck with a similar issue with my test server
SG Inbound: ssh -> 22
HTTP -> 80
NACL: default allow/deny settings
but still couldn't ping to the server from my browser, then I realize there's nothing running on the server that can serve the request, and I started httpd server (webserver) and it worked.
sudo yum -y install httpd
sudo service httpd start
this way you can test the connectivity if you are playing with SGs and NACLs and of course it's not the only way, just an example if you're figuring your System N/W out.
Have you installed webserver(ngingx/apache) to serve your requests. If so please share your the config files. (So that it will help to troubleshoot)
I think the reason is probably that you did not set up a web server for your EC2 instance, because if you try to access http://{PUBLIC_IP} or https://{PUBLIC_IP}, you need to have a background server to serve the http request as #Niranj Rajasekaran said.
By the way, by simply pinging the {PUBLIC_IP}, you could see if your connection to your EC2 instance is normal or not.
In command prompt or terminal, type
ping {PUBLIC_IP}
In my case, the server was running but available on just 127.0.0.1 so it refused connections from external hosts. To see if this is your situation, you can run
netstat -an | grep <port number>
If it says 127.0.0.1:<port number> instead of 0.0.0.0:<port number>, you have this problem.
Usually there's a flag or an argument in your server code somewhere to set the host to 0.0.0.0:
app.run(host='0.0.0.0') # flask example
However, in my case, I had already set this so I thought that couldn't possibly be the issue, which is how I ended up on this thread, which asks more generally about the problem. Unfortunately, I was using docker, and had set 0.0.0.0 on the container but was mapping that explicitly to 127.0.0.1 on the host in the docker-compose port-mapping:
ports:
- "127.0.0.1:<port number>:<port number>"
Changing that line to remove the host IP specification fixed the problem upon re-deploy:
ports:
- "<port number>:<port number>"
There is a related post here: Port mapping in Docker on Mac OSX installed with Docker Toolbox
but it didn't work for me
Get ports for container
docker port 485186e65a5e
8080/tcp -> 0.0.0.0:33360
8088/tcp -> 0.0.0.0:33359
19888/tcp -> 0.0.0.0:33358
50070/tcp -> 0.0.0.0:33357
50075/tcp -> 0.0.0.0:33356
8042/tcp -> 0.0.0.0:33361
Check that someone listens to ports in container
bash-4.1# netstat -alnpt | grep 19888
tcp 0 0 127.0.0.1:19888 0.0.0.0:* LISTEN 1094/java
Do wget in container
bash-4.1# wget 127.0.0.1:19888
--2016-04-11 14:16:54-- http://127.0.0.1:19888/
Connecting to 127.0.0.1:19888... connected.
HTTP request sent, awaiting response... 302 Found
Location: http://127.0.0.1:19888/jobhistory [following]
--2016-04-11 14:16:54-- http://127.0.0.1:19888/jobhistory
Reusing existing connection to 127.0.0.1:19888.
HTTP request sent, awaiting response... 200 OK
Length: 6763 (6.6K) [text/html]
Saving to: `index.html'
100%[================================================================================================================================================================================>] 6,763 --.-K/s in 0s
2016-04-11 14:16:54 (182 MB/s) - `index.html' saved [6763/6763]
Try to access forwarded port from host, no luck... :(((
$docker-machine ip default
192.168.99.100
$ wget 192.168.99.100:33358
--2016-04-11 16:18:04-- http://192.168.99.100:33358/
Connecting to 192.168.99.100:33358... failed: Connection refused.
What do I do wrong?
Omg, desired service started on 127.0.0.1 in container, that is why it wasn't visible from outside world. I've modified service config to start on 0.0.0.0 and now I can access forwarded container port
I had the same problem and was able to fix it by specifying the host that the server within the container uses.
NOTE: when using host below, it means a web server host. When I use host-machine, I mean the main operating system I'm using, (i.e. not a container or a web server, just my laptop as a machine)
The Problem
Running web servers on the container like webpack-dev-server and http-server automatically run the app using a host of http://localhost. Typically you will see that in the output when you start the server. Something like :
Project is running at http://localhost:8080
or
Server available at http://127.0.0.1:8080
On most machines, localhost and 127.0.0.1 are the same thing. This host is not publicly viewable. As a result, your host machine can't see anything, even though it's looking in the right place.
Solution
You should specify a public host when you run the server inside your container.
webpack-dev-server --port 8080 --host 0.0.0.0
or
http-server -p 8080 -a 0.0.0.0
Because the 0.0.0.0 address is viewable to any outside machine, you should be able to see your app working as expected from your host machine.
NOTE: This works for any server, like Python's SimpleHTTPServer, etc. Just look up how to change the host for your chosen server in the documentation
Resources/Nods
(how to run webpack-dev-erver with a publicly accessible host)[How to make the webpack dev server run on port 80 and on 0.0.0.0 to make it publicly accessible?
My lab runs RStudio on a server. A couple weeks ago, from my cousin's house, I successfully ssh'd into the server and pulled up the server-side RStudio through my local Firefox browser. Now when I try to access the server RStudio from home (via my own router), it doesn't work. I need help troubleshooting, and I'm guessing it's some problem on the router. I'm running Mac OSX 10.6.8. No idea what the university server's running, but I don't think it's a server-side problem.
Here's how it worked the first time I did it, at my cousin's house: first, I VPN into the university network; then I call SSH with port forwarding; then I open a Firefox browser, connect to my localhost port, and it opens up RStudio on the server side which I can access through my local browser window.
Here's the problem I'm having right now when I try to log-in from my home network:
I can make the VPN connection successfully. I can also set up SSH successfully with this command:
ssh -v -L 8783:localhost:8783 myacct#server.com
Here are the last several lines of the verbose output from the successful ssh command:
debug1: Authentication succeeded (password).
debug1: Local connections to LOCALHOST:8783 forwarded to remote address localhost:8783
debug1: Local forwarding listening on 127.0.0.1 port 8783.
debug1: channel 0: new [port listener]
debug1: Local forwarding listening on ::1 port 8783.
debug1: channel 1: new [port listener]
debug1: channel 2: new [client-session]
debug1: Entering interactive session.
Last login: Mon Sep 2 04:02:40 2013 from vpnipaddress
So I think I'm still succeeding at the VPN and SSH stage (though I don't know why it says my last login was Sep 2 when I've logged in a few times since then).
Next, I open Firefox, and I type localhost:8783, and instead of getting an RStudio server app through my browser window, I get the following errors:
In the Firefox browser window, it says: Server not found, Firefox can't find the server at www.localhost.com, Check the address for typing errors etc.
In the terminal window, it says:
debug1: Connection to port 8783 forwarding to localhost port 8783 requested.
debug1: channel 3: new [direct-tcpip]
channel 3: open failed: connect failed: Connection refused
debug1: channel 3: free: direct-tcpip: listening port 8783 for localhost port 8783, connect from 127.0.0.1 port 50420, nchannels 4
I'm not sure what I've got wrong. I haven't changed anything on my laptop since my last successful connection. I'm on my own router (instead of my cousin's), so maybe I need to mess with the firewall? I already allowed ports 22 and 8783 to come through the firewall to my laptop (I'm not even sure I needed to do that though). Help?
ssh -v -L 8783:localhost:8783 myacct#server.com
...
channel 3: open failed: connect failed: Connection refused
When you connect to port 8783 on your local system, that connection is tunneled through your ssh link to the ssh server on server.com. From there, the ssh server makes TCP connection to localhost port 8783 and relays data between the tunneled connection and the connection to target of the tunnel.
The "connection refused" error is coming from the ssh server on server.com when it tries to make the TCP connection to the target of the tunnel. "Connection refused" means that a connection attempt was rejected. The simplest explanation for the rejection is that, on server.com, there's nothing listening for connections on localhost port 8783. In other words, the server software that you were trying to tunnel to isn't running, or else it is running but it's not listening on that port.
Posting this to help someone.
Symptom:
channel 2: open failed: connect failed: Connection refused
debug1: channel 2: free: direct-tcpip:
listening port 8890 for 169.254.76.1 port 8890,
connect from ::1 port 52337 to ::1 port 8890, nchannels 8
My scenario; i had to use the remote server as a bastion host to connect elsewhere. Final Destination/Target: 169.254.76.1, port 8890. Through intermediary server with public ip: ec2-54-162-180-7.compute-1.amazonaws.com
SSH local port forwarding command:
ssh -i ~/keys/dev.tst -vnNT -L :8890:169.254.76.1:8890
glue#ec2-54-162-180-7.compute-1.amazonaws.com
What the problem was:
There was no service bound on port 8890 in the target host. i had forgotten to start the service.
How did i trouble shoot:
SSH into bastion host and then do curl.
Hope this helps.
Note: localhost is the hostname for an address using the local (loopback) network interface, and 127.0.0.1 is its IP in the IPv4 network standard (it's ::1 in IPv6). 0.0.0.0 is the IPv4 standard "current network" IP address.
I experienced this error with a Docker setup. I had a Docker container running on an external server, and I'd (correctly) mapped its ports out as 127.0.0.1:9232:9232. By port-forwarding ssh remote -L 9232:127.0.0.1:9232, I'd expected to be able to communicate with the remote server's port 9232 as if it were my own local port.
It turned out that the Docker container was internally running its process on 127.0.0.1:9232 rather than 0.0.0.0:9232, and so even though I'd specified the container's port-mappings correctly, they weren't on the correct interface for being mapped out.
In my case, it worked after running the vncserver on linux.
Entered this on linux command line : sudo ssh -L 5901:localhost:5901 -i <ssh_private_key> <username>#<public-IP-address>
Type there vncserver
Go to VncViewer application and connect using localhost:5901
I used to meet the similar problem because 'localhost' was not available on server when it restarted network service, e.g. 'ifdown -a' but followed by only 'ifup -eo1'. Besides server is not listening to the port, you can also check 'localhost' is available or not.
ps: Post it just hope someone who has the similar problem may benefit.
I had this problem when I wanted to make a vnc connection via a tunnel.
But the vncserver was not running.
I solved it by opening the channel on the remote machine with vncserver :3.
In my case, it worked after checking the correct IP address of the user credentials
previously I was using the wrong IP of the server
ssh -NfL 127.0.0.1:8084:127.0.0.1:8888 user#ip_address_of_server
after correcting it, works fine.
Encountered with the same error.
In my case, I found the problem was in the config file of jupyter.
Let's say there are 3 computers named A, B, and C, and A can access B but can't access C; B can access C.
To access jupyter-notebook service of C from A, first I established ssh tunnel from A to C through B, then I access jupyter-notebook by typing localhost:port_number, then I got the error.
Finally the problem was solved by writing the "c.NotebookApp.ip = '0.0.0.0'" in jupyter-notebook's config file, where '0.0.0.0' allows the access of other IPs.
Hope someone in a similar situation may benefit.
I had the same error when I was trying to tunnel my mlflow ui over ssh to view remotely. As mentioned in the first answer, the error arises because nothing on the server is listening for the port. This, for me, is because I forgot to start the mlflow app on my remote machine! So in general – make sure the app you're trying to access remotely is running.
Just replace localhost with 127.0.0.1.
(The answer is based on answers of other people on this page.)
This means the remote vm is not listening to current port i solved this by adding the port in the vm server