Detect a new network connection (linux-server) and it's status in java

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serverstatusconnectionnetworkdetect
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For the sake of simplicity and without using native code, you could try to using java.net.NetworkInterface with polling, so every X seconds you trigger a network interface enumeration in order to see if there are new interfaces.,Network interfaces go up and down because the network becomes ready / not ready (this typically works by detecting an ethernet carrier or wifi access point), Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers , By clicking “Accept all cookies”, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy.

You can run the program

/sbin/ip
monitor
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Display the status of the devices and connections: # nmcli device status DEVICE TYPE STATE CONNECTION enp7s0 ethernet connected enp7s0, Display the status of the devices and connections: # nmcli device status DEVICE TYPE STATE CONNECTION enp1s0 ethernet connected Example-Connection, Display the status of the devices and connections: # nmcli device status DEVICE TYPE STATE CONNECTION enp7s0 ethernet connected Example-Connection, Create the configuration for the network interface to the internal workstations subnet:

The /usr/lib/udev/rules.d/80-net-setup-link.rules file calls the net_setup_link udev built-in which then applies the policy. The following is the default policy that is stored in the /usr/lib/systemd/network/99-default.link file:

[Link]
NamePolicy = kernel database onboard slot path
MACAddressPolicy = persistent
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The nmcli tool shows the available connections currently used to connect to the network. Enter the following command:,That should do it! But make sure by checking if the new connection is working. Run the nmcli con show command again to start the new connection.,When you added the new connection, autoconnect was set to be true, so it will automatically start if you restart the network utility.,Now you're ready to add a static connection. Using the device name you grabbed from ip add in Step 2, modify and enter the following command to add a new connection:

The ping command is a well-known utility that quickly checks for a connection to an address. Enter the following on the command line:

ping - c3 opensource.com
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Media access control (MAC) address of an Ethernet device. , If your system obtains its IP address from a DHCP server, it is usual for the system to configure the contents of this file with information also obtained using DHCP. , How the interface obtains its IP address: , IPv4 address of the interface.

Each physical and virtual network device on an Oracle Linux system has an associated configuration file named ifcfg-interface in the /etc/sysconfig/network-scripts directory, where interface is the name of the interface. For example:

# cd / etc / sysconfig / network - scripts
# ls ifcfg - *
   ifcfg - em1 ifcfg - em2 ifcfg - lo

The following are sample entries from an ifcfg-em1 file for a network interface that obtains its IP address using the Dynamic Host Configuration Protocol (DHCP):

DEVICE = "em1"
NM_CONTROLLED = "yes"
ONBOOT = yes
USERCTL = no
TYPE = Ethernet
BOOTPROTO = dhcp
DEFROUTE = yes
IPV4_FAILURE_FATAL = yes
IPV6INIT = no
NAME = "System em1"
UUID = 5 fb06bd0 - 0b b0 - 7 ffb - 45 f1 - d6edd65f3e03
HWADDR = 08: 00: 27: 16: C3: 33
PEERDNS = yes
PEERROUTES = yes

If the interface is configured with a static IP address, the file contains entries such as the following:

DEVICE = "em1"
NM_CONTROLLED = "yes"
ONBOOT = yes
USERCTL = no
TYPE = Ethernet
BOOTPROTO = none
DEFROUTE = yes
IPV4_FAILURE_FATAL = yes
IPV6INIT = no
NAME = "System em1"
UUID = 5 fb06bd0 - 0b b0 - 7 ffb - 45 f1 - d6edd65f3e03
HWADDR = 08: 00: 27: 16: C3: 33
IPADDR = 192.168 .1 .101
NETMASK = 255.255 .255 .0
BROADCAST = 192.168 .1 .255
PEERDNS = yes
PEERROUTES = yes
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If the service isn’t running, it might be because a super-server such as an Extended Internet Service Daemon (xinetd) is being used to launch the program when a connection is received. If this is the case, starting the service might have resolved the issue. Run the following command to verify that the issue is resolved:,If a service isn’t running, you can use the service command to start it. The following example starts the httpd service:,When you need to troubleshoot a network service, the first step is to ensure that the service is running.,After you’re sure that the application is running, check the server resources to verify how much your application is consuming.

The following example shows how to check the status of httpd on CentOS by using the service command:

$ sudo service httpd status
httpd is stopped
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A new agent isn't displayed in the user interface, or the agent is reported as offline.,If you cannot connect server to an agent and the agent receives a clock skew exception, complete these actions:,The agent cannot connect to the server,Verify that the agent and agent relay are running the recommended and minimum versions as indicated in the user interface.

agent.out
2017 - 07 - 18 08: 37: 47, 575 INFO AgentWorkerThread com.urbancode.air.agent.AgentWorker - Agent started
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