ping (ICMP protocol) and ssh are two different protocols. It could be that ssh service is not running or not installed firewall restriction (local to server like iptables or even sshd config lock down ) or (external firewall that protects incomming traffic to network hosting 111.111.111.111) First check is to see if ssh port is … Read more
Have a blast at The Ping Page, which has a link to full source on the original Unix ping(8).
You can’t pass it as the argument to call() because the method signature doesn’t allow it. However, you can pass the necessary information as a constructor argument; e.g. public class DoPing implements Callable<String>{ private final String ipToPing; public DoPing(String ipToPing) { this.ipToPing = ipToPing; } public String call() throws SomeException { InetAddress ipAddress = InetAddress.getByName(ipToPing); … Read more
The question was to see if ping responded which this script does. However this will not work if you get the Host Unreachable message as this returns ERRORLEVEL 0 and passes the check for Received = 1 used in this script, returning Link is UP from the script. Host Unreachable occurs when ping was delivered … Read more
You should use nmap: nmap -T5 -sn 192.168.0.0-255 nmap -T insane -sn 192.168.0.0-255 # same as above but w/named template The -T 5/insane option uses the “insane” template, which: insane mode assumes that you are on an extraordinarily fast network or are willing to sacrifice some accuracy for speed. -T4 (aggressive) prohibits the dynamic scan … Read more
Not all machines have nmap available, but it’s a wonderful tool for any network discovery, and certainly better than iterating through independent ping commands. $ nmap -n -sP 10.0.0.0/24 Starting Nmap 4.20 ( http://insecure.org ) at 2009-02-02 07:41 CST Host 10.0.0.1 appears to be up. Host 10.0.0.10 appears to be up. Host 10.0.0.104 appears to … Read more
InetAddress.isReachable() according to javadoc: “.. A typical implementation will use ICMP ECHO REQUESTs if the privilege can be obtained, otherwise it will try to establish a TCP connection on port 7 (Echo) of the destination host..”. Option #1 (ICMP) usually requires administrative (root) rights.
In most cases simply switching the virtual machine network adapter to bridged mode is enough to make the guest machine accessible from outside. Sometimes it’s possible for the guest machine to not automatically receive an IP which matches the host’s IP range after switching to bridged mode (even after rebooting the guest machine). This is … Read more
You should redirect stderr to stdout. To do that, change your exec() call like this: exec(“ping -c 1 $domain_bad 2>&1”, $output, $return_var); More info about 2>&1 meaning here.