I've set up tailscale and connected to an exit node on my VPS on vultr.com. Predictably, I was kicked out and couldn't reconnect, as the VPS's public IP address has changed.
I can reboot the VPS and try again. What steps will I need to take? Does my VPS running behind an exit node even have a unique public address (which?), or does it need to be set up for something like port forwarding?
From looking at tailscale documentation, it looks like they came up with their own ssh, why? Why is the standard ssh inadequate for the purpose? I am not the admin of my tailscale network, and the admin is swamped right now. What can I do?
SSH uses TCP as transport and therefore requires the (srcaddr, srcport, dstaddr, dstport) tuple to be constant over the connection's lifetime.
I believe that since tailscale rotates connections dynamically, it is more suitable for use by clients than servers in a traditional client-server model, unless it provides an 'internal' virtual network over the distributed transport (which would kind of defeat the purpose of covering your tracks).
If you want to connect to your VPS over tailscale, you need to use their tools probably because of that. You can still connect directly to your VPS, though, through plain Internet, if it has any address of its own, and is not firewalled away (or similarly, NATed away). Your provider should either show you the address, or even better, provide access to out-of-band (like serial-port) command line access, where you can query the current addresses using commands like ip addr show.
In your Tailscale Admin console you should be able to see the machine's IP. Just use normal ssh and login that way.
So instead of ssh user#8.8.8.8 you'd do ssh user#100.64.0.1. Tailscale's own ssh client is useful if you want to hook deeper into their MagicDNS stuff, but it's not meant to be the only way to ssh into your machine.
If you run into errors, ping the machine you want to connect to (tailscale ping vps-machine-name). That should help you debug any tailscale client connection problems.
Related
I have a raspi machine behind NAT in my room, and I want to access it from the interenet using the URL.I found this article.
https://developers.cloudflare.com/cloudflare-one/tutorials/ssh
However, it required me to run the cloudflared program on the connecting client. I understand that this is for the security purpose. Does it possible to make the connect without running the cloudflared program on the client machine.
A follow-up question would be is it possible to ssh into ipv6 machine that using the same technique.
There are various options when it comes to connecting to a machine running on a private network:
Running cloudflared on the client (which you already found)
Installing the WARP client on the user side, then using cloudflared on the server side to expose the service securely. Finally, route the network traffic for the private network on the tunnel via WARP. This approach is described in a tutorial here
Cloudflare started also supporting in browser rendering of an SSH session. I have wrote a tutorial describing how to set it up here.
Approach (3) would do away with the need of running a client since it relies on a simple browser.
The entire scenario of my situation seems 10/10 sketchy, I'll admit. So I won't bother convincing you this isn't a malicious attempt to access a server that isn't mine - I'll simply say once, that this is a legitimate need for assistance.
That said, basically my problem goes back to me being a little too restrictive when it came to SSH access to my CentOS 6 server. Basically I restricted access to my custom SSH port from only two IP addresses - one being my home address, and one being my work address - via iptables. The problem is, I no longer work where I do, and my home IP address changed ever since I upgraded my internet.
Obviously this means I no longer am able to connect to my server via SSH since I don't own that IP address anymore.
My question is, is there anything I can do to access this server? I have no console access, but I do at least know the IP address I used to use to log into the server (maybe possible to spoof an IP address, but I have no clue). The only other thing I can think of is I have DirectAdmin installed on the server and can still login with the admin account. Other than that, I've got nothing.
If anyone has any idea on what I can do, it would be greatly appreciated.
You can change the SSH port number from Directadmin file editor (if you have root password),
Then restart the sshd service from service manager
And you can connect to SSH via new port number!
I want to install a number of raspberry pis at remote locations and be able to log in to them remotely. (Will begin with 30-40 boxes and hopefully grow to 1000 individual raspberry pis soon.)
I need to be able to remotely manage these boxes. Going the easier route, forwarding a port on the router and setting a DHCP reservation, requires either IT support from the company we'll be doing the install for (many of which don't have IT), or it will require one of our IT people physically installing each box.
My tentative solution is to have each box create a reverse SSH tunnel to our server. My question is: How feasible would this be? How easy would it be to manage that many connections? Would it be an issue for a small local server to have 1000+ concurrent SSH connections? Is there an easier solution to this problem?
My end goal is to be able to ship someone a box, have them plug it in, and be able to access it.
Thanks,
w
An alternate solution would be to:
Install OpenVPN server on your server machine. How to install OpenVPN Server on the PI. Additionally, add firewall rules that block everything but traffic directed for the client's ssh and other services ports (if desired), from administrating machine(s).
Run OpenVPN clients on your Raspberry PI client machines. They will connect back to your VPN server. On a side note, the VPN server and administrating machine(s) need not be the same machine if resources are limited on the VPN server. How to install OpenVPN on the client Raspberry PIs.
SSH from administrating machine(s) to each client machine. Optionally, you could use RSA authentication to simplify authentication.
Benefits include encryption for the tunnel including ssh encryption for administrating, as well as being able to monitor other services on their respective ports.
I made a WebApp to manage this exact same setting in about 60 minutes with my java web template. All I can share are some scripts that I use to list the connection and info about them. You can use those to build your own app, it is really simple to display this in some fancy way in a fast web.
Take a look at my scripts: https://unix.stackexchange.com/a/625771/332669
Those will allow you to get the listening port, as well as the public IPs they're binded from. With that you can easilly plan a system where everything is easilly identificable with a simple BBDD.
You might find this docker container useful https://hub.docker.com/r/logicethos/revssh/
We have a Win Server 2008 box being hosted (dedicated) for us.
I need to connect to one of it's DB's from a server in our LAN.
What started out as a "sure, I'll just throw that together for you real quick" project has turned into a week-long hair-pulling pile of WTF :)
I am able to RDP into that server without fail or issue.
When I tried to connect to the DB, I got a generic "could not connect" error, so I went hunting.
Telnet attemtps and pings time out.
Since then, we have tried endless variations of firewall settings (including wide open), and still ... no go.
In addition to our firewall, the hosting provider also has a firewall layer.
We turned on all logging, and we don't even see any connection attempts at our FW.
We then had the hosting provider turn on all logging, and they don't see any connection attempts either!
Hrmmmph
I'm at a complete loss.
Any suggestions?
BTW, while I'm comfortable enough with all this to explore and make changes, my experience with firewalls and stuff is fairly limited, so don't hesitate to dumb it down ;)
It is hard to give just one answer to this question, because the interim results of the problem analysis lead to different steps that you need to do next. It will more likely be a step by step help with tracing down the problem.
Do not trust any firewall setting (esp. not any that someone else did, and again esp. not if you don't know him), unless you tested it. Firewall settings are tricky and even experienced professionals get them wrong now and then.
In the guide below, I will write <win2008server> in commands where you have to put the name or IP of the windows 2008 server to which you want to connect. On the other side, I will use the expression "office PC" when I mean your workstation PC in the office from where you are trying to connect to the win2008server.
STEP 1: Checking the Endpoints
1.) Can you telnet to the RDP port?
On your office PC, try this on a command prompt:
telnet <win2008server> 3389
This is to make sure that DNS name resulution works for telnet, as well as network hardware and routing. It should, because you can use RDP to establish this connection. However, anything can get in between, like the telnet command being in any way configured nonstandard or being replaced for whatever reason on a company pc (sysadmins have strange ideas at times...).
2.) Can you telnet locally on the win2008server to the database?
When logged in using RDP on the win2008server, open a command prompt on the server and issue the command
telnet <win2008server> <database port>
That means you are trying to connect from the server to itself. This is to make sure the database port is open on the server.
STEP 2: Checking the Firewalls of the Endpoints
If for 1.) and 2.), your answer is yes it works, you have to test if either the remote side can not be reached or your location can not connect to the internet on the port you are testing (database port). You do this by replacing the respective other side with any other host on the internet for which you know it's reachable or can reach other servers. Typically, you google for a port checker ;)
3.) Check if the win2008server can be reached from another location than yours:
3.1.) Check if the RDP port of the win2008server can be reached from a third party location:
Google for port checker and take the first result (e.g. http://www.yougetsignal.com/tools/open-ports/ ). Type in the name or IP address of the win2008server and the RDP port, usually 3389 . Click on "check" and wait for the success or the timeout.
3.2.) Check if the database port of the win2008server can be reached from a third party location:
Do the same as in 3.1.), just with the database port instead of the RDP port.
4.) Check if you can connect to an outside server on the database port:
For this to work, you need to know a server or create one, which is somewhere outside on the internet, and which listens on the database port. You typically do this by keeping your private PC at home run and accessible through RDP or SSH, and there you open a server and configure your private internet router to forward the connection correctly.
Another way to do this test is webspace with SSH access. Many webspace providers nowadays allow for an SSH login (usually any webspace at $4/month and above).
Let's assume you have SSH access to any such third party place. You can use nc (netcat) there to open a server socket on the database port with this command:
nc -l <database port>
If it's your private PC at home, you usually have to also configure your private router and set up a dynamic DNS name for your internet access for the whole story to work out. You do not have this extra work with a webspace based SSH login. However, there you can not test ports below 1024 because you do not have the privileges. Good luck with this ;)
After you got this, try connecting to the port that you opened:
4.1.) From your office PC with
telnet <third party location> <database port>
4.2.) If 4.1.) does not work, also try with the port checker, because you might have gotten something wrong with setting up the server. Look at 3.) for this, and use the <third party location> and <database port> with the port checker (fourth party check).
STEP 3: Blaming ;)
At least one of the things should have failed by now and you can start calling people and letting them know about your tests and the results. You should be able to combine the results logically, but never start with that. Think about how to convey the information. Start out with your findings and then let them have a moment for their own conclusion. It can be difficult to tell someone in another company or department that their firewall isn't configured correctly. They might deny this even in the presence of proof. Be patient. Explain your findings again. Hint at the conclusion. This can be the trickiest part of the whole problem solution.
I have to say that today I had the same problem.
My solution was just to edit secpol.msc and disable all the FW profiles; then, run services.msc and also disable Windows Firewall service.
After this server was pingable for me.
I want to make my site available world wide. Im using xampp server for hosting. I have no access to any kind of servers and modems. Situation is shown below:
My site server has local ip assigned by wifi router and it runs Windows 8.
Remember I have no access on any kind of servers and modems so port port-forwarding is impossible (out of my scope).
Its actually difficult, but not impossible.
One way, I would approach this is:
I would host a page on internet.
Then take request and store it in database.
One of my program will always be running from my computer.
Then check for request and curl the request to localhost. For this you may use Node.js (taking data from database using GET method and curl it to localhost).
This is the best I could think of. And I am working on it, when the code is ready I'll make it open source and notify you :)
But still, it's difficult, as you need to put user's request to sleep for 2 seconds and then transferring it.
Its slow, but may work out for you.
Disadvantages:
Program will be very slow and memory usage will be more.
Breaking may happen many times.
High bandwidth wastage
If not encrypted, MIM (Men in Middle) may possible.
Advantages:
Indirect method of hosting
Need not to worry about your code being lost.
I am looking forward for a better alternative and I would like to keep this question for bounty once again.
If you cannot open the necessary ports within your LAN you will require access to an external server. However, the external server does not need to host any code, e.g.
Create a Linux based ec2 instance using Amazon's free tier.
Install a package to redirect remote to local ports:
a. using socat:
Install socat using your distributions package manager
Connect via SSH: ssh -N -R 42500:127.0.0.1:80 -o ServerAliveInterval=60 ubuntu#xxx.xxx.xxx.xxx -N -R 8080:localhost:80 "socat TCP-LISTEN:8080,fork TCP:127.0.0.1:42500"
b. using a webserver and reverse proxy:
Install apache or nginx and any required reverse proxy modules and configure your VirtualHost to proxy requests to a local port, e.g. :8080 -> 127.0.0.1:42500
Connect via SSH: ssh -N -R 42500:127.0.0.1:80 -o ServerAliveInterval=60 ubuntu#xxx.xxx.xxx.xxx
Your machine is now reachable via the ec2 instance http://xxx.xxx.xxx.xxx:8080/.
I occasionally use this technique when debugging web service callbacks.
Update 17-02-2014
If you are a Windows user you will need to install a third-party tool to support ssh. Options include:
cygwin
git bash
PuTTY
PuTTY is the easiest choice if you are not familiar with *nix tools. To configure remote port forwarding in PuTTY expand the following setting: Connection -> SSH -> Tunnels. Given the previously described scenario, populate Source port as 42500, Desination as 127.0.0.1:80 and tick the Remote option. (You may also need to add the path to a PuTTY compatible private key in the Connection -> SSH -> Auth tab depending on your server configuration.
To test you have successfully forwarded a port, execute the command netstat -lnt on your server. You will see output similar to:
tcp 0 0 127.0.0.1:42500 0.0.0.0:* LISTEN
Finally you can test with curl http://127.0.0.1:42500. You will see the output of your own machines web root running on port 80.
if you don't have a public IP address and cannot use port forwarding it is impossible to host the site
As people have said you need a public IP address. However, even if you did you should not use xampp as a public server, as it is designed for development and therefore has some security settings disabled.
I would recommend buying some shared web hosting, and uploading it to that. (you can get cheap hosting if you google 'shared web hosting', plus free .tk domains are avaliable: http://www.dot.tk/)
Do your company has any vpn network?
If it does and you have access to the vpn network, you can include your server to the vpn network and your guest will only need to login to your company vpn network then access your site like in a local network without using port forwarding. And since your data is very confidential, I assume that using vpn will also help to increase the security of your data.
Please correct me if I'm wrong.
Thank You.
What you are asking is not possible without port forwarding.
Lets break it into steps.
To host your site locally you will need a IP that is static so that
users can access it specifically.
You will need a domain so that it can be converted into user friendly name.
A 24x7 Internet Connection is must! You added a Wifi Router in your Diagram and most of today's router are capable of port forwarding.
What i will do in your scenario is:
Instead of using XAMP, i will install WAMP because i am more familiar with it and easy to configure.(totally personal preference)
Then i would set my server "ONLINE".(Google how to set WAMP server online)
Forward port "80" from router settings to my local computer ip address.(mostly it is tagged as "Virtual Server","Firewall","Port Forwarding",etc vary router to router in settings)
Suppose you have a local ip "192.168.1.3" and global/router IP "254.232.123.232" then you would redirect all the HTTP request done towards router to your local IP.
[[[[254.232.123.232]]]] --+ :80 +-- --------->192.168.1.3
That is good for now, but then you will need to tackle dynamic IP problem of router. But don't worry, thanks to some free sites that will be easy!
Go to no-ip.org -> Setup Account -> and create a entry, just a subdomain for now to test whether everything is working fine.(subdomain like mysite.no-ip.org, later purchase a real Domain)
Input your IP address there(Router IP) and download its application which will automatically update their server if your local IP changes.
Wait for some minutes and Voila! Your site is live.