62
votes
Accepted
What is the difference between ping localhost and ping 127.0.0.1?
The ping command shows the address it resolved the name to. In this case it resolved to the IPv6 localhost address, ::1. On the other hand, 127.0.0.1 is an IPv4 address, so it explicitly makes ping ...
- 142k
61
votes
Why does 'ping' not output a summary when redirecting output?
ping shows the summary when it is killed with SIGINT, e.g. as a result of CtrlC, or when it has transmitted the requested number of packets (the -c option). CtrlC causes SIGINT to be sent to all ...
- 450k
60
votes
Accepted
What Linux process is responsible for responding to pings?
The kernel network stack is handling ICMP messages, which are those sent by the ping command.
If you do not get replies, besides network problems or filtering, and host based filtering/rate-limiting/...
- 3,180
52
votes
Accepted
"/usr/bin/ping" is shown as yellow-on-red in the default Fedora bash color scheme -- what does it mean?
This indicates that ping has extra capabilities:
$ getcap /usr/bin/ping
/usr/bin/ping = cap_net_raw+ep
or even (on Fedora up to 30):
$ getcap /usr/bin/ping
/usr/bin/ping = cap_net_admin,cap_net_raw+...
- 450k
52
votes
Accepted
What are the differences between iputils-ping and inetutils-ping?
iputils’s ping supports quite a few more features than inetutils’ ping, e.g. IPv6 (which inetutils implements in a separate binary, ping6), broadcast pings, quality of service bits... The linked ...
- 450k
50
votes
Accepted
Why is there output of ping after it has been terminated?
Ctrl+C makes the terminal send SIGINT to the foreground process group. A process that receives SIGINT can do anything, it can even ignore the signal. A common reaction to SIGINT is to exit gracefully, ...
- 22.9k
34
votes
What is the difference between ping localhost and ping 127.0.0.1?
127.0.0.1:
127.0.0.1 is the default loopback of most system. A loopback address is an address used by the system to validate the network stack of the OS.
The loopback address for IPv4 could take any ...
- 9,794
34
votes
Accepted
How can I ping multiple IP addresses at the same time?
If you look into the NMAP project you'll find that it includes additional tools on top of just nmap. One of these tools is nping, which includes the following ability:
Nping has a very flexible and ...
slm♦
- 373k
29
votes
Accepted
Why does 'ping' not output a summary when redirecting output?
Turns out that there is an option in tee to ignore interrupt signals which are sent when CTRL+C is pressed. From man tee:
-i, --ignore-interrupts
ignore interrupt signals
When whole ...
- 1,656
27
votes
Accepted
How to Disable Ping Response (ICMP echo) in Linux all the time?
How would I be able to leave echo off even when I am rebooting my laptop?
You can use one of the following three ways (as root):
Edit /etc/sysctl.conf
Add the following line to your /etc/sysctl....
- 67.7k
24
votes
Check ping statistics without stopping
There is one more easy way to get the ping statistics durning it's execution:
Just press Ctrl + | (vertical slash or it's also called pipe line)
I do personally use it very often, try it:
64 bytes ...
- 361
24
votes
Accepted
Why does ping need setuid permission?
In order for ping to work it needs to be able to create a raw network socket. This is typically a privileged action.
On a modern Linux system this can be granted with "capabilities"
eg on CentOS 7:
...
- 46.3k
22
votes
How can I ping multiple IP addresses at the same time?
fping is in a Fedora package of the same name, and allows for many hosts, or a set of ip addressses.
$ fping -a -A -c 1 hosta hostb
192.168.0.20 : xmt/rcv/%loss = 1/1/0%, min/avg/max = 0.64/0.64/0.64
...
- 52.3k
20
votes
Accepted
Trying to write a shell script that keeps testing a server remotely, but it keeps falling in else statement when I logout
When GNU grep tries to write its result, it will fail with a non-zero exit status, because it has nowhere to write the output, because the SSH connection is gone.
This means that the if statement is ...
- 341k
18
votes
Accepted
Why is the output on this ping outside the subshell?
The warning is sent to ping’s standard error, which isn’t captured. If you want to ignore it, redirect it to /dev/null explicitly:
connected=$(ping -I $1 -qc 1 8.8.8.8 2>/dev/null \
&& ...
- 450k
18
votes
Why can I access a server by a partial IP address?
That is an allowed form according to the inet_aton(3) function docs:
DESCRIPTION
inet_aton() converts the Internet host address cp from the IPv4 num‐
bers-and-dots notation into ...
- 35.2k
18
votes
Accepted
No internet connection in chroot environment (customizing iso)
You have internet connection, as evidenced by the ping to 8.8.8.8. You just don't have DNS name resolution.
See the file /etc/resolv.conf in your root file system and copy it to the chroot ...
- 9,091
17
votes
How can I ping multiple IP addresses at the same time?
I would suggest using GNU Parallel
parallel -u ping ::: host1 host2 host3
output will be interleaved
- 505
15
votes
What are the differences between iputils-ping and inetutils-ping?
inetutils-ping is the portable GNU implementation, which is used on non-Linux Debian systems (such as Debian GNU/kFreeBSD).
iputils-ping is Linux only, but does have more features. If you are using ...
- 15.2k
14
votes
What Linux process is responsible for responding to pings?
There is no userland process responsible for responding to pings. Ping is just a utility to send ICMP echo packets. These are received and process by the kernel's networking stack
- 1,219
13
votes
Accepted
Need Improvement on Script Which Continuously Tests Website
You don't need ; at the end of each line, this is not C.
You don't need:
cp /dev/null pingop.txt
because the very next line in the script
ping -i 1 -c 1 -W 1 google.com > pingop.txt
will ...
- 25.7k
12
votes
The difference between 'ping' and 'wget' in relation to hostname resolution
Answering to:
What is the difference between 'ping' and 'wget' in relation to hostname resolution
Ping expects either an IP address or a hostname as parameter. You are giving it a full URL which ...
- 61.8k
12
votes
Continuous ping loop in script
Do you mean something as simple as this:
while :; do
ping -c 1 -w 3 8.8.8.8; echo $? > /tmp/ping.status
sleep 1
done
That will write the exit status of ping to /tmp/ping.status once a ...
- 245k
11
votes
Check ping statistics without stopping
Linux (Tested on Ubuntu 20.04)
Send the SIGQUIT signal.
Example output:
64 bytes from localhost (127.0.0.1): icmp_seq=138 ttl=64 time=0.021 ms
64 bytes from localhost (127.0.0.1): icmp_seq=139 ttl=...
11
votes
What Linux process is responsible for responding to pings?
The kernel itself (not any user process) is responsible to sending ICMP echo reply messages in response to ICMP echo request messages. So, if a host stops responding to pings, it is usually due to ...
- 3,176
10
votes
Accepted
Shell command/script to see if a host is alive?
Ping is great to get a quick response about whether the host is connected to the network, but it often won't tell you whether the host is alive or not, or whether it's still operating as expected. ...
- 7,073
10
votes
Check ping statistics without stopping
On Mac it's Ctrl+T.
Ctrl+\ does the same as Ctrl+C, as it stops the ping after showing the stats.
- 293
10
votes
From 192.168.0.146 icmp_seq=1 Destination Host Unreachable
[edit] My other devices can ping my PC, but my PC can not ping any other device including the router to which my PC is attached directly.
I would check for a conflicting IP address on another device.
...
- 51.4k
10
votes
Accepted
ping: show only results
Another awk variation:
ping -qc1 google.com 2>&1 | awk -F'/' 'END{ print (/^rtt/? "OK "$5" ms":"FAIL") }'
-F'/' - treat slash / as field separator
Example output:
OK 47.090 ms
- 30.5k
Only top scored, non community-wiki answers of a minimum length are eligible