I just recently got into whatever you might call this stuff. I was just trying to send a java file over to the computer I ssh to. But when I went to do it, I just get told
sh: connect to host port 22: Connection timed out
lost connection
If possible I would like it explained very simply because of how new I am to this kind of stuff.
SSH to remote host(VM Ubuntu) from VS code terminal
Install VS Code with Remote Development extension pack.
Install Virtual machine (Virtual box) and Ubuntu running on it.
Check Ubuntu-Network-Settings-IPv4 address (10.0.2.15-default for VM).
Go to your virtual box Settings-Network-NAT Adapter (double-check).
Go to your virtual box Settings-Network-In Advanced-Port Forwarding.
Add this as given below and click ok and hereafter consider 127.0.1.1 for ssh.
portforwardinginVM
View the status and disable firewall settings in Ubuntu VM (ufw command).
In VS Code, View-Command Palette- Add new SSH host .
Add ssh username#127.0.1.1 and enter.
Or go to the terminal window (eg. Powershell) and type ssh username#127.0.1.1, it will ask if you want to update to host lists permanently, asking like yes/no and also your Ubuntu password to confirm.
Now try to connect to the host using username#127.0.1.1 and selecting OS like Ubuntu, then type the Ubuntu password.
That's it you are logged in to your virtual machine and can access files now from your local machine.
I have used these instructions for Running Gui Apps with Docker to create images that allow me to launch GUI based applications.
It all works flawlessly when running Docker on the same machine, but it stops working when running it on a remote host.
Locally, I can run
docker --rm --ti -e DISPLAY -e <X tmp> <image_name> xclock
And I can get xclock running on my host machine.
When connecting remotely to a host with XForwarding, I am able to run X applications that show up on my local X Server, as anyone would expect.
However if in the remote host I try to run the above docker command, it fails to connect to the DISPLAY (usually localhost:10.0)
I think the problem is that the XForwarding is setup on the localhost interface of the remote host.
So the docker host has no way to connect to DISPLAY=localhost:10.0 because that localhost means the remote host, unreachable from docker itself.
Can anyone suggest an elegant way to solve this?
Regards
Alessandro
EDIT1:
One possible way I guess is to use socat to forward the remote /tmp/.X11-unix to the local machine. This way I would not need to use port forwarding.
It also looks like openssh 6.7 will natively support unix socket forwarding.
When running X applications through SSH (ssh -X), you are not using the /tmp/.X11-unix socket to communicate with the X server. You are rather using a tunnel through SSH reached via "localhost:10.0".
In order to get this to work, you need to make sure the SSH server supports X connections to the external address by setting
X11UseLocalhost no
in /etc/ssh/sshd_config.
Then $DISPLAY inside the container should be set to the IP address of the Docker host computer on the docker interface - typically 172.17.0.1. So $DISPLAY will then be 172.17.0.1:10
You need to add the X authentication token inside the docker container with "xauth add" (see here)
If there is any firewall on the Docker host computer, you will have to open up the TCP ports related to this tunnel. Typically you will have to run something like
ufw allow from 172.17.0.0/16 to any port $TCPPORT proto tcp
if you use ufw.
Then it should work. I hope it helps. See also my other answer here https://stackoverflow.com/a/48235281/5744809 for more details.
Though browsing several websites and here on stack overflow, there seems to be a way to view the messages in an Activemq queue using Jolokia and Hawt.io, but I have been unsuccessful to this point.
We are running our Activemq (version 5.12.0) as in embedded service in our Spring Webapp and exposed the Jolokia web services as explained in this webpage:
https://jolokia.org/reference/html/agents.html#agent-war-programmatic
When looking that the Jolokia web services via Hawt.io, I can not figure out how to actually view the messages in the queue.
Here is a screenshot showing the queue size:
So, how can I view the messages in an Activemq queue using Jolokia and Hawt.io?
The solution we ended up going with didn't actually use Jolokia or Hawt.io.
We ended up using Jconsole.
When looking at ActiveMQ queues, if you used a java serialized object in the queue, the data won't be very readably, but if you serialize your object to json, it is quite easy to see what is in the queue.
It is terribly important to read these directions all the way though, carefully.
These instructions discuss SSH Tunneling and it is quite easy to mess something up and there are not very good log messages when things go wrong.
Remote Debugging
Due to security reasons, we have closed all the open debug ports on our remote virtual machines.
To get remote debugging to work, we will need to use SSH Tunneling to access the remote virtual machine debugging ports.
Remote Application Setup
The application that you want to remotely debug must have the JPDA Transport connector enabled.
After Java 1.4, to enable the JPDA Transport, add the following vm parameter when starting your java virtual machine:
-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=<remote_port_number>
The above attributes are hard to describe, but what is presented above works well. More information about the above attributes can be found on the Connection and Invocation Details page.
Local IDE Setup
In Intellij to connect to a remote java virtual machine, open the "Run/Debug Configurations" window.
Then select a new "Remote" configuration.
Enter the following values:
Debugger mode
Attach to remote JVM
Host
localhost
Port
<local_port_number>*
Use module classpath
<local_package>**
The <port_number> should be the local port number of the ssh tunneling session that you will be starting. It is recommended that the <remote_port_number> and the <local_port_number> are the same value.
** This value should be whatever your local project is named.
SSH Tunneling
To actually connect to the remote debugging port, we'll need to use SSH Tunneling.
Run the following command via a terminal command line:
$ ssh -L <local_port_number>:localhost:<remote_port_number> -f <username>#<remote_server_name> -N
Example:
$ ssh -L 10001:localhost:10001 -f <your_username>#<your.server.com> -N
This command does the following:
Starts an ssh session with the <remote_server_name>.
Connects your <local_port_number> to the <remote_port_number> of the localhost of the remote machine. In this case, we're saying connect to localhost:10001 of the <your.server.com> machine.
Start remote debugging in the Intellij IDE and you should then be connected to the remote java virtual machine.
Resources
Intellij IDEA remotely debug java console program
Remote debug of a Java App using SSH tunneling (without opening server ports)
Remote JMX
We use JMX to look at the Spring Integration Kaha DB Queues.
Remote Application Setup
Add the following vm parameters:
-Dcom.sun.management.jmxremote.port=64250
-Dcom.sun.management.jmxremote.rmi.port=64250
-Dcom.sun.management.jmxremote.authenticate=false
-Dcom.sun.management.jmxremote.ssl=false
-Djava.rmi.server.hostname=127.0.0.1
The jmxremote.port and jmxremote.rmi.port can be any number and they can be different values, it just helps if they are the same value when doing the ssh tunneling below.
SSH Tunneling
$ ssh -L 64250:localhost:64250 -f <your_username>#<your.server.com> -N
JConsole Setup
This is done in a new terminal window.
$ jconsole -J-DsocksProxyHost=localhost -J-DsocksProxyPort=64250 service:jmx:rmi:///jndi/rmi://127.0.0.1:64250/jmxrmi
Resources
Why Java opens 3 ports when JMX is configured?
Clean Up
To close the ssh processes above:
$ lsof -i tcp | grep ^ssh
Then perform a kill on the process id.
Using jps and jstack to Help Debug
List all java processes running on a machine:
$ sudo jps
List the threads of an application running:
$ sudo -u <process_owner> jstack <process_id>
Example:
$ sudo -u tomcat jstack <pid>
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I am trying to connect to remote server via ssh but getting connection timeout.
I ran the following command
ssh testkamer#test.dommainname.com
and getting following result
ssh: connect to host testkamer#test.dommainname.com port 22: Connection timed out
but if try to connect on another remote server then I can login successfully.
So I think there is no problem in ssh and other person try to login with same login and password he can successfully login to server.
Please help me
Thanks.
Here are a couple of things that could be preventing you from connecting to your Linode instance:
DNS problem: if the computer that you're using to connect to your
remote server isn't resolving test.kameronderdehamer.nl properly
then you won't be able to reach your host. Try to connect using the
public IP address assigned to your Linode and see if it works (e.g.
ssh user#123.123.123.123). If you can connect using the public IP
but not using the hostname that would confirm that you're having
some problem with domain name resolution.
Network issues: there
might be some network issues preventing you from establishing a
connection to your server. For example, there may be a misconfigured
router in the path between you and your host, or you may be
experiencing packet loss. While this is not frequent, it has
happenned to me several times with Linode and can be very annoying.
It could be a good idea to check this just in case. You can have a look
at Diagnosing network issues with MTR (from the Linode
library).
That error message means the server to which you are connecting does not reply to SSH connection attempts on port 22. There are three possible reasons for that:
You're not running an SSH server on the machine. You'll need to install it to be able to ssh to it.
You are running an SSH server on that machine, but on a different port. You need to figure out on which port it is running; say it's on port 1234, you then run ssh -p 1234 hostname.
You are running an SSH server on that machine, and it does use the port on which you are trying to connect, but the machine has a firewall that does not allow you to connect to it. You'll need to figure out how to change the firewall, or maybe you need to ssh from a different host to be allowed in.
EDIT: as (correctly) pointed out in the comments, the third is certainly the case; the other two would result in the server sending a TCP "reset" package back upon the client's connection attempt, resulting in a "connection refused" error message, rather than the timeout you're getting. The other two might also be the case, but you need to fix the third first before you can move on.
I got this error and found that I don't have my SSH port (non standard number) whitelisted in config server firewall.
Just adding this here because it worked for me. Without changing any settings (to my knowledge), I was no longer able to access my AWS EC2 instance with: ssh -i /path/to/key/key_name.pem admin#ecx-x-x-xxx-xx.eu-west-2.compute.amazonaws.com
It turned out I needed to add a rule for inbound SSH traffic, as explained here by AWS. For Port range 22, I added 0.0.0.0/0, which allows all IPv4 addresses to access the instance using SSH.
Note that making the instance accessible to all IPv4 addresses is a security risk; it is acceptable for a short time in a test environment, but you'll likely need a longer term solution.
If you are on Public Network, Firewall will block all incoming connections by default. check your firewall settings or use private network to SSL
The possibility could be, the SSH might not be enabled on your server/system.
Check sudo systemctl status ssh is Active or not.
If it's not active, try installing with the help of these commands
sudo apt update
sudo apt install openssh-server
Now try to access the server/system with following command
ssh username#ip_address
This happens because of firewall connection.
Reset your firewall connection from your hosting website.
It will start working.
After connecting to the server again add this to your (ufw) security
sudo ufw allow 22/tcp
There can be many possible reasons for this failure.
Some are listed above. I faced the same issue, it is very hard to find the root cause of the failure.
I will recommend you to check the session timeout for shh from ssh_config file.
Try to increase the session timeout and see if it fails again
My VPN connection was not enabled. I was trying all possible way to open up the Firwall and Ports until I realized, I am working from home and my VPN connection was down.
But yes, Firewall and ssh configurations can be a reason.
Try connecting to a vpn, if possible. That was the reason I was facing problem.
Tip: if you're using an ec2 machine, try rebooting it. This worked for me the other day :)
I had this issue while trying to ssh into a local nextcloud server from my Mac.
I had no issues ssh-ing in once, but if I tried to have more than one concurrent connection, it would hang until it timed out.
Note, I was sshing to my user#public-ip-address.
I realized the second connection only didn't work when I tried to ssh into it when on the same network, ie my home network
Furthermore, when I tried ssh user#server-domain it worked!
The end fix was to use ssh user#server-domain rather than ssh user#public-ip
I have experienced a couple of nasty issues that lead to these errors, and these are different from everyone else's answer here:
Wrong folder access rights. You need to have specific directory permissions on you ssh folders and files.
a. The .ssh directory permissions should be 700 (drwx------).
b. The public key (.pub file) should be 644 (-rw-r--r--).
c. The private key (id_rsa) on the client host, and the authorized_keys file on the server, should be 600 (-rw-------).
Nasty docker network configuration. This just happened to me on an AWS EC2 instance. It turned out that I had a docker network with an ip range that interfered with the ssh access granted by the security group and VPC. The docker network's range was e.g. 192.168.176.0/20 (i.e. a range from 192.168.176.1->192.168.191.254), whereas the security group had a range of 192.168.179.0/24; interfering with the SSH access.
I had this error when trying to SSH into my Raspberry pi from my MBP via bash terminal. My RPI was connected to the network via wifi/wlan0 and this IP had been changed upon restart by my routers DHCP.
Check IP being used to login via SSH is correct. Re-check IP of device being SSH'd into (in my case the RPI), which can be checked using hostname -I
Confirm/amend SSH login credentials on "guest" device (in my case the MBP) and it worked fine in my attempt.
I faced a similar issue. I checked for the below:
if ssh is not installed on your machine, you will have to install it firstly. (You will get a message saying ssh is not recognized as a command).
Port 22 is open or not on the server you are trying to ssh.
If the control of remote server is in your hands and you have permissions, try to disable firewall on it.
Try to ssh again.
If port is not an issue then you would have to check for firewall settings as it is the one that is blocking your connection.
For me too it was a firewall issue between my machine and remote server.I disabled the firewall on the remote server and I was able to make a connection using ssh.
my main machine is windows 10 and I have CEntOS 7 VBox
Search in your main machine for "known_hosts"
usually, known_host location in windows in "user/.ssh/known_host"
open it using notepad and delete the line where your centos vbox ip
then try connect in your terminal
in mac os user you can find known_hosts in "~/.ssh/known_hosts"
Make sure to ask the admin to authorize your device.
On Linux run:
sudo zerotier-cli listnetworks
if it returns status ACCESS DENIED ask the admin to authorize your node. This is mentioned here.
https://discuss.zerotier.com/t/solved-cant-join-network/1919
This issue is also caused if the Dynamic Host Configuration Protocol is not set-up properly.
To solve this first check if your IP Address is configured using
ping ipaddress,
If there is no packet loss and the IP Address is working fine try any other solution. If there is no response and you have 100% packet loss, it means that your IP Address is not working and not configured.
Now configure your IP Address using,
sudo dhclient -v devicename
To check your device you can use the 'ip a' command
For eg. My device was usb0 since I had connected the device through usb
This will configure an IP Address automatically and you can even see which one is configured. You can again check with the 'ip a' command to confirm.
This may be very case specific and work in some cases only but
check to see if you were previously connecting through some VPN software/application.
Try connecting again to the VPN. Worked in my case.
This happened to me after enabling port 22 with "sudo ufw allow ssh". Before that, I was getting a refusal from my machine when entering with ssh from another one. After enabling it, I thought it would work, but instead it showed the message "connection timed out". As I had just installed Ubuntu with the option of installing basic functions alongside, I checked whether I had the openssh-server with the command sudo apt list --installed | grep openssh-server. It turned out that Ubuntu had installed by defect the openssh-client instead. I uninstalled it and installed the openssh-server following the basic commands:
sudo apt-get purge openssh-client
sudo apt update
sudo apt install openssh-server
After that, a simple "sudo ufw allow ssh" worked perfectly and I was finally able to access the machine with an ssh command.
What worked for me was that i went to my security group and reset my IP and it worked
Here are some considerations which i took to resolve a similar issue that I had:
Port 22
IGW (Internet Gateway)
VPC
Scene 1> This is for port 22 not enabled with right configurations. If the port is set to custom or myip, the probable scene is this won't work.
Scene 2> When you delete the internet gateway, the network is created and the instance will be functional too, but the routing from the internet will not work. Hence make sure that if there is a VPC, it has an Internet Gateway attached.
Scene 3> Check the VPC for the subnet associations and routing table entries. This might probably tell you the cause. I found one in this kind of troubleshooting. The route used to land up in a "blackhole" (shows up in the route table section of the console). To fix this I had to check and find out my internet gateway and found the issue with the IGW.
Moral of the story: always trace backward in the network!
In my case I'm on windows, I reset my firewall settings, and it fixed
If you get any error check the basic a version control request with ssh -V and If it is not installed, install it with the sudo apt-get install openssh-server command.
Check your virtual machine ssh connection with sudo service ssh status at console.
Check "Active" rows and if write a inactive(dead) the console write sudo service ssh start
Result: Now you can check your connection with sudo service ssh status command and send ssh connection request.
Reset the firewall and reboot your VPS from your hosting service, it will start working perfectly fine
check whether accidentally you have deleted the default vpc or default subnets ,while creating your own vpc and subnets.
I have done this mistake while creating vpc, hence got this error while connecting via ssh.
alos check whether u have attched IGW to public subnets.
Its not complicated.
First, go disable your firewall(USE YOUR CONTROL PANEL)after you check if your openssh is active.
Disable firewall, then use putty or any alternative to basically disable using this command sudo ufw disable
try now
Update the security group of that instance. Your local IP must have updated. Every time it’s IP flips. You will have to go update the Security group.