So I am pretty new to all of this and currently learning about ssh and NAT.
So I have a VM setup on Azure and in order to connect to it I need to ssh into it. But the problem is I am unable to ssh into it because I am behind a NAT as I am currently studying in a University, hence getting "connection timed out" error all the time.
Also I have tried changing the default port(22) to 443 or 80 still same error which confirms I am behind a NAT.
So currently the only way to ssh is to use a VPN which works fine.
But after researching a bit I found that I can also use Reverse SSH Tunneling to achieve the same but couldn't figured out a way of how to do it. I know it is a bit riskier than using a VPN only but anyway just wanted to try.
So can anyone help me?
An outgoing SSH connection (your machine -> Azure VM) should not be affected if you are behind a NAT. NAT usually blocks incoming SSH access to your machine not out from it.
Also I have tried changing the default port(22) to 443 or 80 still the same error which confirms I am behind a NAT.
You changed the default port on which machine, you or the Azure VM? Changing the default port on your machine will not affect the outgoing SSH connection as it is only for incoming SSH connection to the SSH server on your machine (if you have one running locally).
Your best bet would be to actually look at the security groups of the Azure Virtual Network you VM is located in. Make sure it allows incoming SSH connection on port 22 to your VM.
Related
I have the following problem I'm trying to solve.
I wanted to use deployHQ to deploy code on commits to my repository.
deployHQ configuration asks for Hostname Port Username and no-password.
deployHW are using Keypairs for identity validation (and authorization), so deployHQ provide me with a public-key to setup in my end machine authorized_keys store.
But, my machine is on a Private VPC in AWS.
So, I thought I can setup an SSH proxy, that operates on different ports.
Each port would proxy the connection to a different machine on the Private VPC part.
But, I am literally clueless on how to do it!! I understand it's not SSH tunnelling, and not TCP forwarding, but nothing really works for me.
The general idea is simple:
SSH using port 18022 to my bastion/proxy to funnel the communication to 10.10.0.2:22 in AWS Private VPC
SSH using port 18023 to my bastion/proxy to machine B:22
SSH using port 18024 to my bastion/proxy to machine C:22
SSH using port 18025 to my bastion/proxy to machine D:22
If anyone knows how to do this, or, thinks of better idea, I would really appreciate the help.
So... the solution to this is actually very simple...
Setting up reverse NAT on IpTables on the Bastion, pointing external ports to resolve to 22 on different servers.
Super simple.
I have two Azure VMs I set up to test a program I made. The program is to be run on both VMs, where synchronous operations are performed, requiring the VMs to communicate with eachother on different ports using TCP protocols. To access my Azure VMs, I SSH'd into them on port 22 using Putty on my local machine. The VMs are on the same subnet, and I am trying to get them to communicate with eachother via their public IP. I have set up both VMs inbound rules to accept messages from eachother on any port, using any protocol here is an example of this.
During the execution of my program, I encounter the following error "Unable to connect to remote host: Connection refused". After this, I did some investigating. First, I had both VMs ping eachother, which they successfully did. Then, on both VMs, I ran the command "telnet other.ip 22", where other.ip is the other VMs public IP. This seems to work, as seen in this image. When I run "telnet other.ip 6000", or any other port besides 22 for that matter, I get the same error of "Unable to connect to remote host: Connection refused". My rational is that if I can get the "telnet" command running on any port, that my program will likely work too.
I am not too sure what my issue could be at this point, and my internet searches have not helped me. I doubt there is an issue of a port being backlogged with communication requests given my current inbound rules. Also, I did try to change my inbound rules so that my VMs would receive messages on any port, using any protocol, from any source, which resulted in the same error (I then changed it back from 'any source' to only my other VMs public IP for security purposes).
According to your description, you may check two points:
If there is any firewall inside the VM that is blocking the connection from the external network with port 6000. For example, if you are using Ubuntu VM, you can refer to How to Set Up a Firewall with UFW on Ubuntu 18.04. Then disable the firewall with the command sudo ufw disable or add a firewall rule to verify this.
Run the command on Linux to see open ports. sudo netstat -tulpn | grep LISTEN. You should see port 6000 in the output. If not, it might mean that your program is not started well.
Let me know if you have any concerns.
Check your firewall rules. If your organization tent to use firewall then add port 6000 in inbound and outbound chain.
you can connect the remote host with port number only when it is in listening state.
sudo netstat -tulpn | grep LISTEN.
I'm getting stuck here, so i have an amazon ec2 (standard redhat server) host up and working. i can connect to it personally no problem, however it cannot be connected to outside of my ip.
I've checked the rules and i have port 80 and 3000 open to 0.0.0.0/0 to be able to communicate, however outside of my computer (and computers in this network) i can not connect.
Everything I've found is about connecting to ssh which works fine, i have no rules in iptables, i haven't dealt much with them before, but since i can connect to the service i don't think its the issue.
summary:
Web server is running, i can connect from my computer to it, and any others in my local network, but nothing outside of it works.
i do have httpd installed as well as a simple forward from the browser to port 3000, however i cant connect to it either from outside my network.
so this is a new one for me, the dns forwarding works in houst, but not outside. so inside and outside here, i can use IP address to connect, but inside only i can connect with my dns lookup. not sure what caused this, but its not an amazon problem at least. going to look at that side.
I've been having problems SSHing into my work computer from home. I have been able to succesfully ssh into one of our web servers so I know the ssh daemon is working and my connection is at least allowing some ssh. But when I try to ssh to my work computer it times out.
I went to my University yesterday and I was able to succesfully ssh into both the web server and my work computer. I've looked into our firewall at work to see if there are any blocks on my IP but it isn't blocked.
My ISP is comcast if that helps at all. I've done a few google searches and some comcast customers say that comcast sometimes blocks file sharing ports such as the ssh port (22).
Any help would be appreciated. Thanks.
First check the /etc/hosts.deny file of your work computer. That may contain lines which might suggests that certain IP may be blocked. Then check /etc/hosts.allow file. You can add your home-computers outgoing IP to your work computers /etc/hosts.allow.
NOTE: This question should belong to superusers or serverfault. stackoverflow is for questions that involves coding...
There is not one single "ssh daemon"... there is one running on each host to which you connect successfully. If you cannot connect to a host there are two primary reasons:
There is no SSH daemon running on the host. In that case you will likely get "connection refused"
There is a firewall between you and the host, and it is not allowing port 22 to pass through. In that case you will likely get timeouts.
If you are trying to connect to a host behind a firewall from "outside", as you suggest, it is extremely likely that host is not reachable from the Internet. If the IP address of the "work computer" looks like 192.168.x.x or 172.[16-31].x.x or 10.x.x.x then it is an unroutable private address and you will not be able to reach it from the outside no matter what you do unless a specific port-forwarding rule is set up on the firewall; in that case you would be connecting to the firewall's IP address, not your target host.
I created a VM in a VPN in Windows Azure. I added TCP endpoints for the particular machine which runs server 2012. But everytime I run a small program listening on TCP like the example in nodejs, any client simply refuses to connect. This happens even when I disable the firewall? I tried with linux (ubuntu) too. Can someone help me out and let me know what steps I am missing? I connected with:
server1.cloudapp.net:tcp_port
RDP and SSH work fine through TCP.
Here are a few things to check, which may provide more clue.
1) double check your endpoint, make sure the public port and private port are set correctly
2) rdp to the VM and do "netstat -an" to check if the port is indeed listening