I have a host laptop running Debian, and a client VM running Debian. On the client, I run NGINX, and it serves up a complex web application with several hostnames (e.g. www.host, api.host, blog.host). The laptop moves between several different networks, with a seemingly ever-changing IP address.
I'm trying to meet the following conditions with this VM:
The IP address of the client shouldn't change (e.g. always 192.168.10.10)
With a static IP, I could edit the host /etc/hosts file and keep complex hostnames
The client should have access to the Internet
No other machines need to access the client
What is the best way to set up the Attached to settings for this client?
To do this, simply add two network interfaces to the box.
The first interface will use Host-Only, and that is how your host can connect to the client. This will create an additional network adapter on the host.
The second interface will use NAT, and that is the gateway to the internet. This will create an additional network adapter on the client.
If you've already got a client running, you'll need to get the next network adapter up and running by executing sudo ifconfig eth1 up and to get an IP address, run sudo dhclient eth1.
Related
My company has an on-premise network which is opened by OpenVPN server.
In the ordinary scenarios, I used to connect to that server very easily.
However, when I tried to that server from the OCI compute instance which I connected by SSH from my laptop, there exist some problems. As soon as I try to connect VPN server, my SSH connection is closed.
IMHO, this may occurred because VPN connection changes network information and so my SSH connection might be lost.
I tried to look around to find out how to connect to VPN from OCI, but almost everything was using IPSec protocol which Oracle provided, others were about builting OpenVPN Server on the OCI instance.
I'm very novice for the network structure. So, please give me some hint to resolve this problem.
Thanks,
I get the following:
You have Ubuntu 18.04 VM on a Public Subnet in OCI
You have OpenVPN Server running on On-Prem.
You would like to access your On-Prem from Ubuntu VM on OCI.
If I understood it correctly, the best way is to set up IPSec VPN. It isn't that hard if you hit right steps. At the high level, you will be doing the following steps. I have used IKEv1 in my attempts in the past.
OCI:
Create a DRG
Attach/Associate it to your VCN
Create a CPE (Customer Premise Equipment) and mark the IP Address of OpenVPN server to it.
Create an IPSec Connection on the DRG. It will create two Tunnels with its own Security Information.
Set up Routing on associated subnet (i.e., one that hosts Ubuntu VM) so traffic associated to On-Prem CIDR are routed to DRG.
On-Prem:
Create necessary configuration to create the Tunnels upto OCI (Using the configuration information from previous steps such as VPN Server IP Addresses and Shared Secrets)
Set up Routing so that the Traffic destined for OCI CIDR ranges are sent to associated Tunnel Interface
This ensures that you can create multiple VMs on the OCI Subnet all of which can connect to your On-Prem infrastructure. OCI Documentation has sufficient information in setting up this VPN Connection.
Alternatively if your only requirement is to establish connectivity between Ubuntu VM on OCI to OpenVPN server On-Prem, you might use any VPN Client software and set it up. This doesn't need any of the configuration steps mentioned above.
Worker nodes in private subnets have private IP addresses only (they do not have public IP addresses). They can only be accessed by other resources inside the VCN. Oracle recommends using bastion hosts to control external access (such as SSH) to worker nodes in private subnets. You can learn more on using SSH to connect through a bastion host here - https://docs.cloud.oracle.com/en-us/iaas/Content/Resources/Assets/whitepapers/bastion-hosts.pdf
I'm trying to set up a container with docker.
The container can access the internet while I'm under my home network which doesn't have any filter, but fails to connect while under the university network (I can't even docker run ubuntu ping 8.8.8.8. I just get nothing). From my experience the university network drops everything that's not on port :80 and is not an http/https/ftp(and similar protocols) request.
I can ask for a specific MAC address to not be filtered.
With which MAC address does docker interface with internet?
Does it use my wireless board? I think it creates a new interface, but I have no idea if all the containers traffic goes through it.
Which MAC address should I ask to unlock in order for my containers not to be filtered?
Thanks!
I can ask for a specific MAC address to not be filtered. With which MAC address does docker interface with internet?
When communicating with the outside world, Docker is using the MAC address and source IP address of your host. If you are connected to the University network using your wireless NIC, then this is the NIC that Docker containers use for external connectivity.
Docker creates a bridge device on your system named docker0. All containers connect to this bridge, and use a private range of ip addresses. Communication external to your host happens via NAT rules configured using iptables (you can view them by running iptables -t nat -S). These rules make traffic originating in Docker containers appear to originate from your host instead.
I have implement a Client-Server application in java. The server can serve multiple clients, and I want to test that, but my knowledges on Networking is poor, and I need a way to test my application on my home.
I have a rooter, which are connected both of my computers. My "server" class in java uses as host the local host (127.0.0.1) on a given port.
How can I test my program if
The Server.java is running on the Computer A
Server.java is running on 127.0.0.1 on 3943 port
1st Client.java is running on the Computer A
1st Client.java is connected to 3943 port
2nd Client.java is running on the Computer B
2nd Client.java is connected to 3943 port
Any ideas?
Use unique ports for the clients and servers running on the same machine. In addition 127.0.0.1 is localhost (internal to that machine). Computer B cannot communicate with 127.0.0.1 on Computer A. Use 127.0.0.1 if all applications or on the same machine. Use the computers actual IP address if you want external machines to be able to communicate with the server.
When client and server, are on the same computer, what you are doing must be already working.
To connect from a different computer, you need to find the "real" ip address of your server.
If you are on Windows, open a command shell on your computer A, and run ipconfig. On unix/linux/mac, run ifconfig.
Look for a string, looking like an ip address, but not 127.0.0.1, there has to be another one if you are connected to a network, probably looks like 10.0.0. or 192.168.<0 or 1> ..
Use this address everywhere instead of 127.0.0.1
A full TCP connection consists of two different endpoints. The server side of the connection is one endpoint (it will be do a listen on that endpoint). When a client creates it's side of the connection (the client socket), it will do a connect to the server ip:port combo and get a number assigned from a range of so-called "ephemeral" ports.
The fact that both sides of the connection have the same IP address doesn't matter - the full connection is defined by two distinct elements (address:port combinations).
FirstClient's connection to the server will be ServerIP:ServerPort<->Client1_IP:Client1_Port, and SecondClient's connection will be ServerIP:ServerPort<->Client2_IP:Client2_Port. The network layer can differentiate between these (they are two different connection streams) and route traffic to the appropriate sender/receiver for that stream.
If you run the server bound to IP 127.0.0.1 you are not opening it to the network, only your own computer will be able to connect to it, acessing 127.0.0.1 (loopback IP address).
To open this server to the network, you must do one of the two things:
Bind it to the IP 0.0.0.0 so it will be acessible from all networks;
Bind it to a specific network IP address so that it will be available to that network only.
Its common practice to just bind it to 0.0.0.0, its easier.
Once its done, you will be able to connect from other computers to the server running on computer A, however, not through IP 127.0.0.1. Thats the loopback address and can only be used by a computer to connect to itself.
Computer A can use the IP 127.0.0.1 to connect to the server since the server is running on it, but other network computers will have to specify computer A's network IP address.
You can find your IP address on the network adapter details, or running the command ipconfig /all on a command prompt (Windows) or ifconfig (Linux).
I have a general question regarding binding and connecting to localhost. I am using a TCP client/server and on the server side I do sth of the form:
bind(localhost, 9999);
listen();
This is done on a unix host with a name e.g. host1
Now, the client is running on a separate Windows box, on the same network. In order to connect I tried to connect via hostname:port, hostIp:port but none of that succeeds.
Is this because binding to localhost is not visible across the network for other processes to connect to and is used for e.g. client/server running on the same machine?
If you are binding to localhost (i.e. 127.0.0.1), you can only accept connections from the localhost, not over the network.
If you need to accept remote connections over the network, you should either bind to one of the local IP addresses (e.g. 192.168.0.10) or all interfaces (i.e. 0.0.0.0).
This is due to the fact that 127.0.0.1 is always local loopback address, and as such never routed over the network.
How can a Linux VM work out the IPaddress of the host node?
I need to connect to the IP address of the host node. I also need to know when it changes as it could be a dynamic IP. I need it to connect to a service there.
Is there some way to check this, irregardless of the type of VM, VMWare, Xen, Virtual Box?
It needs to be a Linux script, and should work regardless of the host operating system, whether Linux or Windows
My solution is to bridge a network adapter in the VM with one on the host, making it a dymanic IP address. As such it will always be on the subnet as the host adapter.
Next thing is to run an HTTP service on the host IP, that the VM will scan its network range on. The IP the service responds on will be the IP of the host. Having an IP service on the host is not ideal, but it is the best I can come up with.