I am using mininet and ODL controller. Previously, when I was using the CLI to create topology and connect to my controller (which is installed on another virtual machine), it was pinging fine between all the hosts and life was good.
Now I'm not able to ping between hosts. Specifically when I build one switch with two hosts, because when I build 3 switches sometimes two hosts will ping each other.
I did h1 arp command on mininet and it was showing HardwareAddress incomplete and sometimes the iface is displaying:
image
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I am trying to set up OpenVPN so that I can access machines inside an Azure subnet from my pc which is outside Azure.
I have successfully installed OpenVPN on both server (Windows Server 2019) and pc (Windows 10) using the instructions here: https://community.openvpn.net/openvpn/wiki/Easy_Windows_Guide?__cf_chl_jschl_tk__=pmd_889e3e419b8b865ffd4da6e493bef6df0782273e-1629275604-0-gqNtZGzNAfijcnBszQgi, and I can successfully connect from client to server, however, I cannot connect to any other machine on the Azure subnet upon which the server is sitting.
The server and the other machines I want to connect to are on a 10.0.0.0 subnet, and the VPN is coming up on the 10.8.0.0 network as I would expect from the examples.
I have enabled IP routing on the server as recommended in the OpenVPN FAQ but this has not fixed the issue.
I have also added a 'push "route 10.0.0.0 255.255.255.0"' line to the server config, and I can see from the client log (and the client routing table) that this has been executed, but I am still unable to connect to other machines in the subnet.
I was looking into using Tap instead of Tun, but when I dug into at what was actually being used, it looks as if as if both ends are using the Tap adaptor anyway, even though I have specified 'dev tun' in both the client and the server configs.
I have had bit of a trawl but can't find anything about the Tap adaptor when the Tun adaptor has been configured, so that is a bit of a mystery.
The only other thing that I have read is that it might be necessary to set up a route back to the OpenVPN subnet on the gateway server for 10.0.0.0, but that's not a server I control as it's part of the Azure infrastructure.
What do I have to do to get access to other machines on the 10.0.0.0 subnet? And why is the Tap adaptor being selected despite the config specifying the Tun adaptor ?
I made a number of other changes before I finally got it sorted out - I do not know if they were all necessary but in addition to the above:
I changed 'dev tun' to 'dev tap' in the server and client configs.
I followed the instructions here NAT-hack to add NAT to the server.
And finally, I added 'route 10.0.0.0 255.255.255.0 10.8.0.1' to the
server config file.
I have installed and configured a 3 monetdb nodes cluster on 3 virtual machines on my MacBook (Using Oracle Virtual Box). I use MonetDB 5 server 11.37.7
I have followed the Cluster Management documentation of MonetDB, but the monetdb discover command only returns the dbfarm of the local instance. Each node still isn't aware of other nodes.
I can connect to any nodes from any other node using monetdb -h [host] -P [passphrase], I can also discover the remote farms of a specific host by using monetdb -h host -P passphrase discover
The answer to this question monetdb cluster management can't setup helped me in setting the listenaddr property to 0.0.0.0, but still, the discover command only returns the local monetdb farm.
EDIT
Thanks to Jennie suggestion below, I noticed that the monetdb log file contains error while sending broadcast message: Network is unreachable.
I used netcat utility to brodcast UDP message from one node to the other 2 and it worked, I can ping, ssh and the 3 nodes are part of the same network configured with virtualbox, but the error is still there.
All your VMs must be in the same LAN environment. monetdb discover basically goes over all IP addresses under the same subnet.
Can you some how verify that's the case?
I got it working, thanks to #Jennie's post. For anyone using VirtualBox:
Use the first network adapter of each configured node with Bridge access instead of NAT
Configure the following property of your dbfarm: listenaddr=0.0.0.0
For testing purpose, it may be worth reducing the property discoveryttl to less than the default 10mns
I have a Velodyne Puck 16 sensor that I have been trying to connect to ROS Melodic for the past few days. My OS is Ubuntu 18.04. I was able to find out the address of the lidar using WireShark, as it is possible to see below:
So the IP is: 10.0.1.201
After very very carefully following the installation procedure in the official documentation everything I was trying was unsuccessful.
So I decided to apply a simple ping procedure to the address of the lidar:
ping 10.0.1.201 it does not return any package of information despite it seems connected.
The problem I have is that, despite I know the IP address of my Velodyne 16 using Wireshark, the lidar does not answer to a simple test as the ping of the id.
Steps I followed:
1 Configure your computer’s IP
Below the connection procedure: I created a velodyne_interface connection, see below:
Existing Connection
velodyne_interface
2 Connecting your computer to LIDAR through terminal
emanuele#pc:~$ sudo ifconfig enp109s0 192.168.3.100
Add a static route to the LIDAR's IP address.
emanuele#pc:~$ sudo route add 10.0.1.201 enp109s0
3 Checking the configurations [Problem is here]
To check the connection open your web browser and access the following sensor’s network address.
The problem is that I never get to see the webpage showing the lidar data. Basically I never get to see the page below provided in the official documentation:
What is happening? Why is that happening?
There is probably some problems with the routing. You can try debugging the routing issues, some googling will probably help there. Some commands which might help pinpoint the problem tracepath -n 10.0.1.201 and ip route list.
The easiest solution to your problem would be to just configure the "velodyne_interface" you created to the same subnet as your velodyne lidar. So in the "velodyne_interface" set your ip to 10.0.1.20 for example. Connect to the "velodyne_interface" connection, verify that you have the ip you set by typing ip a or ifconfig in some terminal and you should be able to access the Velodyne web interface from 10.0.1.201. From there you can configure the velodyne sensor networking to the settings you like.
Initially, i set up 2 machines (Ubuntu 12.04, x64) on vSphere server.
The name and ip of these two machines were
host ip
vm-cluster-node1 10.211.55.100
vm-cluster-node2 10.211.55.101
I have installed cloudera manager in vm-cluster-node1.
Then i cloned second one (vm-cluster-node2) to create 2 more hosts, and changed the ip and names as:
host ip
vm-cluster-node3 10.211.55.102
vm-cluster-node4 10.211.55.103
But the problem is, when i add these all 4 machines from cloudera, no matter how many times i try, i can only see two machines in hosts tab. later i realized that, if i refresh the web-page, i can see 2 machines only, but the second machine is switched between vm-cluster-node2, vm-cluster-node3 and vm-cluster-node4.
to illustrate, i have included images to make things clear.
So, as far i've understood, the cloudera manager is not able to resolve the hosts cloned from same source as different machines. Even though the host-names and IPs have been changed. So is there anything that is common in these machines and this problem is occurring?
SOLVED
The problem was that the three nodes/hosts have same HOST ID. This can be changed in /etc/hosts/cloudera-scm-agent file with CMF_AGENT_ARGS="--host_id new_host_id"
I am trying to host Minecraft servers in docker containers on an ec2 instance, and point a different subdomain to each container, for example
a.example.com -> container 1
b.example.com -> container 2
c.example.com -> container 3
...and so on.
If these containers were running a website, I could forward the traffic with Apache, or node-http-proxy, etc. But because these servers are running TCP services, I cannot route the traffic this way.
Is this possible? And if so, how?
The Minecraft client has supported SRV DNS records for a while now (since 1.3.1 according to google). I suggest you assign your Docker containers a stable set of port mapping with the -p flag, and then create SRV records for each FQDN pointing to the same IP but different ports.
Google gives several hits on the SRV entry format - this one is from the main MCF site: http://www.minecraftforum.net/topic/1922138-using-srv-records-to-hide-ports-on-your-server-ip/
I have four MC servers running on the same physical host with a single IP address, each with a separate friendly entry for players to use in the Minecraft client, so none of my users need to remember a port. It did cause confusion for a couple of my more technical players when they had a connectivity issue, tested with dig/ping, then thought the DNS resolution was broken when there was no A record to be found. Overall, I think that's a very small downside.
Doesn't HAProxy http://haproxy.1wt.eu/ route tcp traffic?