I am facing a strange issue these days. I have a list of IP addresses which I want to connect to during the deployment using Jenkins. Now what is happening is, if I am deploying at one IP address (remote machine but in same location) in my local location server, I can successfully do that. But If I am trying to deploy to an IP address (remote machine in other country/region) It is throwing the error, saying
Error : Ip address XYZ is not reachable or is invalid.
Please be notified that I am able to get the response from the machine when I ping it using:
ping XYZ
But while trying to deploy on it using Jenkins, I am not.
Please let me know if there's any solution for this problem.
There isn't enough data points but you can look for these things
1. IP address, Check if all three machines are in same n/w (Jenkins Server, target and your machine)
You can check it with IP address of each machine
2. check Gateway set for Jenkins server
3. Best way if feasible is to ssh / rdp to your Jenkins server and try running your command manually that will give you
Local machine get loopback address(127.0.0.1), so it will be reachable or any local machine having IP address with same subnet mask thats called LAN.
When you are reaching out to remote machine, either it should be public IP address(visible to everyone in the world) or you must have connect to that Area-Network via VPN, this is called tunnelling to remote over the WAN (wide area network). Their(remote location) again, you will notice that all the IP address have same subnet mask as you have on the local machine.
So their could be be IP address duplication case in VPN scenario, where you are bale to ping but not able to reach. This is because, IP address is assigned to other machine but not you yours and ping responses are coming from that other machine. That means your machine is in failed to resolve ARP and in dormant state.
Related
Let's say we have a wifi at home. When I google "whatsmyip", it gives me public IP address, which is essentially IP address of my router on the internet.
Now lets say I have two machines (A and B) both hosting a web server. I want to reach to a web-server on my machine 'A' from outside my local network (from some other corner of the world), how I can ping to that specific machine to my network. I understand for outgoing requests from my machine we have NAT, but what about incoming request to a specific machine? How router resolves it?
How I can check that IP(for incoming requests) in my windows/linux machine?
e.g let's say I have a tomcat server running on port 8080 on machine A. Now if I do localhost:8080/home, it displays "Hello World". Now one of my friend in let's say in Europe wants to access "/home" end point. What ip would he use?{IP}:8080/home. Means how he'll identify my machine, as to the internet only router's IP address is visible
To be able to reach your comptuer on the LAN behind your router you will need to do a port forward.
All connections to your public x.x.x.x:p ip/port address are forward to y.y.y.y:p
You can't forward different connections with the same port to a different machine in your lan, you will have to implement a more sophisticated approach to be able to do that, like a load balancer and apply a rule's base on the domain etc.
To be able to ping, you have to forward ICMP request to your lan machine.
I have a bit of a bizarre problem. I have a Hyper-V VM and I cannot connect to it via IP address on the host computer.
I intend to use it as an SQL server to host a database for a website while I test it, and the first step I can see in this endeavour is to make sure the IP addresses work externally.
Other PCs on the LAN appear to be able to connect just fine via the IP address on Remote Desktop. I cannot do so. I also cannot connect through SQL Management Studio (named pipes or TCP/IP). Although named pipes gives an error relating to being denied access as opposed to IPs which are just not found.
I have tried pinging both ways:
VM => Host : Always gives a "Destination Host Unreachable" error
Host => VM: Always gives a "Request Timed Out" error
As for netstat -a -n, I can see that the VM is listening to 3389 (default Hyper V port, which makes sense).
Regarding Firewalls, all have been turned off on all machines. I can tell that the firewall is not the issue.
If you need any more information to help me to diagnose and treat the problem, please ask me as I would like to get this sorted as quickly as possible.
Thanks a lot in advance.
Which windows server version do you use?
Windows Server 2016 blocks insecure RDP connections (https://support.microsoft.com/en-us/help/4295591/credssp-encryption-oracle-remediation-error-when-to-rdp-to-azure-vm).
Since RDP uses CredSSP you have to install the current Windows Patches.
Do you can ping the DNS server by IP address from your VM?
Is ICMP (ICMP = the thing you need for ping) on your host enabled?
Here is a Checklist for ICMP:
https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/cc749323(v=ws.10)
Solved,
Just switched to another physical computer and it was fine.
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).
Given that the local machine has multiple interfaces and I connect to a remote machine, the OS will choose the interface through which the remote IP address is reachable. If my client doesn't explicitly bind to a specific IP and if the remote machine is reachable via more than one interface, is there a way to detect which local IP address will be used for the communication or is it purely random?
In Linux at least, it needs to have the route specified in the routing table, it is not random.
Like if one is on 192.168.1.1 and the other on 192.168.1.2, can you configure the machine's to each other's static IP addresses and thereby have them start receiving information for each other's InstanceInputEndpoints (since now the Azure gateway should route the InstanceInputEndpoint to the new owner of the IP address)?
No, you can't do that!
And, as of today (Dec. 2013) you are highly advised to never set static IP Address of your Virtual Machine inside Windows Azure! You should always use default DHCP configuration. If you wand IP Address predictability check out this blog post. You can still use Azure Virtual Network with Web and Worker Roles and have IP Address predictability.
If you use VM you should create several VM and a Networks, define address space you will use. When you create a VM, make sure your VM is using the networks that you create. If you forget to include the vm into the network, you need to recreate the VM.
Example how to change the internal IP using 3 VM:
Server A is connected to the network and get ip 192.168.0.1
Server B 192.168.0.2
Server C 192.168.0.3
shutdown all your server from azure portal so that the status is deallocated then turn it on with this sequence:
Server B
Server C
Server A
The Result will be:
Server A 192.168.0.3
Server B 192.168.0.1
Server C 192.168.0.2
If you turn off the VM from inside the VM, it won't be change the internal IP.
If you remote onto one of your VMs, you will see an XML file at
C:\config
The filename looks something like
[deployment id]_[role name]_[instance number].[version number]
Inside the file you will find all the instances in the deployment with their IP addresses. If you edit the IP address in this file for a particular role instance on a particular VM, that VM will think that the IP address for the instance is the one in the file and will start routing traffic to it.
Warning: I've never tried to do this programmatically. Also, the changes will get wiped out if there is any update to the deployment (either initiated by you or by Azure). And there might be some other horrible side effect.