A tool commonly used to test the reachability of a given host, either on the internet or in a local network.

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30
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3answers
86k views

What could DUP mean when using ping?

What could DUP mean when using ping?
17
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3answers
19k views

Can one ping a NIC by MAC

I have an NIC card on a Debian machine somewhere. The machine is turned off, but I need to know whether the NIC card is turned on so that I can send a wake-on-lan magic packet later (from another ...
16
votes
7answers
15k views

Faster way than ping for checking if computer online?

I'm writing a wake on lan script for a set of our lab computers. We have sqlite db with a list of the computer hostnames, IPs, and MACs and currently I ping each of them with '-c1' so it doesn't run ...
12
votes
3answers
7k views

How to redirect the output of any command?

I'm trying to write a simple script to monitor my network status, without all of ping's output: ping -q -c 1 google.com > /dev/null && echo online || echo offline The problem is that ...
10
votes
2answers
3k views

Check ping statistics without stopping

Is there a way to tell ping to show its usual termination statistics without stopping the execution? For instance, I'd like to quickly view: --- 8.8.8.8 ping statistics --- 2410 packets transmitted, ...
7
votes
4answers
48k views

Why can't I ping Google?

I can't ping google.com (unknown host). But I can ping IP addresses. I tried to ping the IP address of Google but it doesn't work. resolv.conf nameserver 8.8.8.8 nameserver 209.139.209.33 ...
6
votes
1answer
304 views

-m option does not work in ping command

I was learning the Linux ping command and its options, and read about the -m option which is used to mark the outgoing packet. When receiving, we can filter that marked packet result first. I am ...
6
votes
1answer
2k views

root owned program with setuid bit on

Ping is a a program owned by root with the user id bit set. $ ls -l `which ping` -rwsr-xr-x 1 root root 35752 Nov 4 2011 /bin/ping As I understand it, if a user runs the ping process, then the ...
6
votes
1answer
511 views

Why the difference between network addresses reported by hostname and ping?

I have tried hostname and ping in a cluster machine, with different outputs. I am wondering what is the difference between the two? For example, on the same machine, hostname outputs node4.XXX and ...
6
votes
3answers
17k views

How does traceroute resolve names?

While writing a script, I wanted to reference a machine by the computer name that I gave it (e.g. "selenium-rc"). I could not ping it using "selenium-rc", so I tried the following commands to see if ...
6
votes
1answer
3k views

Shell command/script to see if a host is alive?

I'm trying to figure out more ways to see if a given host is up, solely using shell commands (primarily bash). Ideally, it would be able to work with both hostnames and IP addresses. Right now the ...
6
votes
4answers
20k views

What prevents a machine from responding to pings?

I have a CentOS release 5.4 linux box on Amazon EC2 that I'm trying to set up to be monitored via Nagios. The machine is in the same security group as the nagios server, but it seems to be ...
6
votes
1answer
80 views

-T option result in ping command

I was learning about the ping command. I am not able to understand the output of ping command with -T tsonly and -T tsandaddr. The output is: $ ping -T tsonly 192.168.1.52 PING 192.168.1.52 (192....
6
votes
2answers
1k views

Why is ping much faster when using -f

I'm pinging the same host from the same machine at the same time. And when using -f, the result is almost twice as good: [root@localhost Desktop]# ping 196.1.6.16 PING 196.1.6.16 (196.1.6.16) 56(84) ...
6
votes
2answers
363 views

Is there an ICMP echo request service?

Often, in applications that I develop, I like to include a network status indicator for various devices on the network. The easiest way to monitor these devices is by pinging them. But ICMP echoes are ...
5
votes
3answers
2k views

ping to send 0 bytes

Is it possible for ping command in Linux(CentOS) to send 0 bytes. In windows one can define using -l argument command tried ping localhost -s 0 PING localhost (127.0.0.1) 0(28) bytes of data. ...
5
votes
4answers
4k views

“internet connection checker one-liner”

With this I can check, that there is "internet connection". if there is no "internet connection" (succesfull pings to this 2 places), then it waits 600 sec, then it runs along: ping -W 1 -c 4 www....
5
votes
2answers
5k views

Can't ping broadcast

We're running four computers connected to a hub (yes a hub not a switch) on Fedora 13. They were installed using images from a colleague that has recently left us to go back to school, they may have ...
5
votes
2answers
3k views

My Ping command does not seem to ever finish. Does that mean it is suceeeding?

I am pinging a remote IP. I know very little about the Ping command. When I ping the IP, it keeps going and going... I am not using the -t option. Me$ ping 137.30.124.104 PING 137.30.124.104 (137.30....
5
votes
3answers
1k views

Is there some way I can start a (repeating) ping while the network is unreachable?

My ping command (on Debian 6 or 7) will repeatedly attempt to ping a server even while the network is down, if the network was up when it was started. Is there some way to start ping while the network ...
5
votes
1answer
3k views

Ping doesn't work, but I can browse through the internet

Pinging my default gateway is working properly and I can browse google and facebook in my browser. But, ping google.com and ping facebook.com on my terminal are not working. PING google.com (216.58....
5
votes
3answers
202 views

SSH to two addresses, use the one that connects first

I have a home computer (let’s call it franklin because that’s what I call it) that I often ssh into from my work laptop. When I’m at home, I ssh to franklin.local, and when I’m at work or anywhere ...
5
votes
2answers
72k views

Host unreachable and I do not get why

I can not open a specific website. This is a website hosted by our company, and I know it is up. However, these are my symptoms: VARIABLES: host.com - the website I can not open x.x.x.x - the IP of ...
5
votes
1answer
3k views

Very slow response from localhost when pinging

Networking is working fine on my gentoo machine. One connection is made, everything works fine with normal speed. But it is slow to wake-up : starting up connection is taking time. Even pinging local-...
4
votes
3answers
11k views

How can i check that a remote computer is online for ssh / script acess?

i'm writting a script that will backup data from my laptop to an ubuntu server. to do so, i'm looking for a (ba)sh command to test if the server is available before starting the backup. something like ...
4
votes
5answers
503 views

How to log Internet connection drops

I need to execute a script as soon as my raspberry pi gets connected to the Internet. However I was wondering if there was a better way than just pinging Google every minute or so. My problem is that ...
4
votes
1answer
353 views

Redirection to file does not work properly

I have here a bash script: #!/bin/bash TARGET_FILE=ping_result.txt # declare the target ip addresses declare -a ips=("XXX.XXX.XXX.XXX" "YYY.YYY.YYY.YYY") function print_and_log() { echo "$1" ...
4
votes
2answers
8k views

What is the difference between ping -w and ping -W?

What is the -w (deadline) flag in ping for? I cannot find a description of it in the ping man page; only for -W, which takes seconds as a parameter. What is the difference between them, and how can I ...
4
votes
2answers
5k views

Why am I getting DUP! reply when using ping -A

We have 2 VM's running on ESX 5.1. When I do a ping -A, after a while I get every second ping as a DUP!. When doing a normal ping, I get 5 or 6 DUP!s, and then it returns to normal. Any ideas what to ...
4
votes
2answers
184 views

Why does ping run forever by default in Linux? [closed]

What was the rationale for the design decision to make ping's default behavior to ping forever? For example, the following basic usage will ping address 127.0.0.1 forever: $ ping 127.0.0.1 ...
4
votes
2answers
5k views

Cannot access to web server, but can ssh to it

I have a Ubuntu server but there are some weird things I can't understand. I cannot ping to the server via IP address, but I can ssh to it. I can access to apache server inside the server via command ...
4
votes
2answers
140 views

Did this tutorial block pings to my server?

I am a programmer teaching myself linux admin stuff. I followed this tutorial to setup a firewall on a VPS. As a part of that tutorial, I block all traffic except for web traffic and SSH traffic. I ...
4
votes
1answer
270 views

Strange ping behavior

I built a linux distribution using the Yocto Project, with little customization. It runs on a Single Board Computer. When I ping this machine, I get the following result: PING 10.128.11.1 (10.128....
4
votes
1answer
3k views

qemu - two clients (tap0 & tap1) via br0 can't ping eachother but server pings ok

I've got: A host system running Ubuntu with KVM (functional) Two clients, one Ubuntu and one Windows 7, nothing fancy. I've also setup (see below) a bridge via br0 for the clients: br0: 192.168....
4
votes
0answers
65 views

How can I know which IP address of a host is reachable from another?

I don't particularly need a "solution" to something, I'd just like to understand more of the landscape here. So on my CentOS box, I installed a CentOS VM specifically for learning Puppet. When the ...
3
votes
3answers
9k views

traceroute gives only stars + how to fix

Please advise about the following problem. When I do: $ traceroute 8.8.8.8 I get in the output showing only stars, even though pinging to google.com ( 8.8.8.8) appears to be working. Please ...
3
votes
2answers
182 views

Why doesn't iptables receive the marked packet?

I was learning the ping command options. In that I found the -m option to set the mark for a packet. The below command sends the packet with marking of 10 to the 192.168.2.65. ping -m 10 192.168.2....
3
votes
1answer
141 views

Some ICMP-Reply messages don't arrive in User Space in recent Kernels

I'm moving an application from 2.6.23 (yes, it's ancient; that's why we are moving) to 3.18LTS. The application monitors multiple network links to the same target with ping packets. The different ...
3
votes
3answers
177 views

For some IPs, ping -c 4 -W 1 ip | cat does not output anything until ping has finished, whereas it does for others

Why do $ ping -c 4 -W 1 127.0.0.1 | cat and $ ping -c 4 -W 1 1.1.1.1 print their output immediately, whereas $ ping -c 4 -W 1 1.1.1.1 | cat prints nothing for four seconds, then prints all ...
3
votes
1answer
18k views

Cannot reach outside network or IP after upgrading to Ubuntu 12.04

I am running Ubuntu 12.04 on my server but since the upgrade from 10.04 I can no longer reach any outside sources of the server. I can SSH into the box, but from inside here I can not reach anything. ...
3
votes
1answer
66 views

Why ping receives another ping command packet?

I am learning about the ping implementation in C. The problem is, I was using a raw sockets to receive the packet. For all packets we have a identification value in ICMP header. I was running the ...
3
votes
1answer
110 views

What ports need to be open on a firewall to access the internet?

Let's say as the example that I have a firewall that blocks ALL ports from all sources/destinations. What ports would I need to open to be able to successfully run: ping google.com ...and are ...
3
votes
1answer
7k views

recvmsg returns 'EAGAIN (Resource temporarily unavailable)'

After a recent server move, we are troubleshooting this wierd issue of one of the server losing n/w connectivity for no apparent reason and regaining the connectivity in a few seconds or minutes. ...
3
votes
2answers
1k views

Suppress “Alarm clock: 14” from ping

I've made a simple script for rebooting my router and afterwards showing a progress bar until my computer has an internet connection again. When running the script I get the following output: The ...
3
votes
2answers
2k views

ping -c1, wait for all responses from broadcast

I want to send one packet to the broadcast address, but wait for all responses. If I do ping -c 1 192.168.1.255, it sends just one packet, but it quits after getting the first response.
3
votes
1answer
22 views

Cannot ping OUT of a Mac OS X server

I have just inherited a Mac OS X server that is using pf. The problem I am trying to solve is why I can't ping OUT of the server. I can ping to the machine no worries, but just get timeouts on pinging ...
3
votes
1answer
271 views

Wget and curl can work normally, but ping fails

When I ping www.google.com and 8.8.8.8, I get no reply: # ping www.google.com PING www.google.com (216.58.221.228) 56(84) bytes of data. ( no response) # ping 8.8.8.8 PING 8.8.8.8 (8.8.8.8) 56(84) ...
3
votes
1answer
4k views

LAN server with two network cards, can't telnet / ping to the second even if it works

I have an issue with an Ubuntu 12.04 LTS (updated) server. For reasons too long to detail, it has got one eth0 interface assigned to 192.168.1.9 and one Wifi wlan0 interface assigned to 192.168.1.10. ...
3
votes
3answers
4k views

Problem pinging from a specific interface

I'm trying to ping from a specific interface, I have a wired and a wireless connection both going into my laptop. My wired adaptor eth0 is on the IP 172.16.109.75 My wifi adaptor wlan0 is on the IP ...
3
votes
1answer
41 views

Forward ICMP Ping Packets to Interface

I've got a script that listens for ICMP ping packets (containing data payload) and while this works if you run it from command line, it doesn't work in a Docker container because ICMP ping packets are ...