How to use ping Command

One of the most commonly-used commands on Linux is the ping command, used most often to test network connections and troubleshoot connectivity issues. It comes by default on most Linux distributions, making it accessible.

You may even have used ping or seen it used, supplying the command with a hostname or IP address and seeing it go to work.

But ping has numerous options, giving it a wide range of capabilities and testing and troubleshooting scenarios to cover.

Reading the Results of the ping Command

Before starting in on how to use ping, it can be helpful to know how ping displays results. To get your footing with that, look into an example ping command that sends one packet to the localhost as follows:

ping -c 1 localhost

PING localhost(localhost (::1)) 56 data bytes
64 bytes from localhost (::1): icmp_seq=1 ttl=64 time=0.113 ms

--- localhost ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.113/0.113/0.113/0.000 ms

The line beginning 64 bytes indicates a packet. There may be several of these depending on the command parameters, and these lines can give you the most insights on the ping instance.

Here, that line is broken down to show the role each part plays. You can use the explanation as a basis to effectively interpret similar lines for your ping commands.

64 bytes shows the number of bytes in the packet. The default is 56 (seen in the first line of output), which translates to 64 bytes for the ICMP protocol used by ping.
from localhost (::1) shows the destination host. You can see that this also resolves the given hostname (localhost) into its IP address.
icmp_seq=1 shows the ICMP sequence number for each packet. This starts at 1 and increases by one for each packet sent in a ping instance. So, if this example had sent four packets instead of one, you could expect icmp_seq=1, icmp_seq=2, icmp_seq=3, and icmp_seq=4.
ttl=64 indicates the “time to live” for the packet, which is the number of network “hops” the packet can make before it expires.
time=0.113 ms shows the amount of time the ping action took. This is often the most important piece of information, as it helps you determine how the efficiency of the packet communication.

At the end of each ping instance, you receive a set of summary statistics, beginning with localhost ping statistics in the example above. These statistics indicate packet transmission and loss as well as round-trip time (rtt) statistics for the sent packets. The summaries can be especially useful when you want overall impressions from ping instances that have numerous packets.

Basics of the ping Command

In the next several sections, you can learn how to conduct basic ping operations, from pinging a host to fine-tuning how your pings work. This section also answers your questions on how ping handles ports and how to use ping for resolving hostnames to IP addresses.

Ping a Hostname

The ping command at its simplest just takes a hostname or a host IP address as an argument. It then details if the host is reachable from your computer or server.

To get a ping of the localhost, you can use the hostname:

ping localhost

PING localhost(localhost (::1)) 56 data bytes
64 bytes from localhost (::1): icmp_seq=1 ttl=64 time=0.117 ms
64 bytes from localhost (::1): icmp_seq=2 ttl=64 time=0.079 ms
64 bytes from localhost (::1): icmp_seq=3 ttl=64 time=0.109 ms
64 bytes from localhost (::1): icmp_seq=4 ttl=64 time=0.135 ms
64 bytes from localhost (::1): icmp_seq=5 ttl=64 time=0.118 ms

--- localhost ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4077ms
rtt min/avg/max/mdev = 0.079/0.111/0.135/0.021 ms

The ping command keeps running until you manually stop it. You can manually stop it from sending packets using the Ctrl + C key combination. There are also a few options, covered further on, that designate endpoints for ping, causing it to automatically stop at predetermined points.

Ping an IP Address

The same method can be used for IP addresses. Just replace the hostname with the host’s IP address. For the example above, you could use 127.0.0.1 instead of localhost:

ping 127.0.0.1

PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.127 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.136 ms
64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.127 ms
--- 127.0.0.1 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2042ms
rtt min/avg/max/mdev = 0.127/0.130/0.136/0.004 ms

Ping a Specific Port

The ping command does not allow for the specification of a port to ping. And, further, ping does not even operate on a specific port.

This is because ping uses the ICMP protocol. Unlike the TCP and UDP protocols, ICMP does not regard ports.

Resolve a Hostname

With the ping command, any input hostname is automatically resolved, rendering the associated IP address. You can see this in the first line of output from ping instances.

Take a look at this example. It pings the google.com hostname, and, in the first line of output, you can see that the hostname has been resolved to an IP address:

ping google.com

PING google.com(atl14s08-in-x0e.1e100.net (2607:f8b0:4002:818::200e)) 56 data bytes
[...]

The IP address above is IPv6, the default in ping. You can learn more about this option below, but ping also supports displaying IP addresses in the IPv4 format:

ping -4 google.com

PING google.com (142.250.177.14) 56(84) bytes of data.
[...]

Options for Fine-tuning

The options covered in this section are ones that you may find more generally useful. They are options that you may find yourself more frequently using to make the ping command perform how you would like.

IP formatting can be either IPv4 or IPv6. The ping command defaults to IPv6 on most Linux distributions. But you can explicitly indicate which format you want ping to use with the 4 option for IPv4 and the 6 option for IPv6:NoteOn some Unix systems, ping does not include these options. Instead, ping may default to IPv4 and come with the ping6 command installed alongside. The ping6 command can then be used for IPv6 formatting.
```
ping -4 localhost
```
```
PING localhost (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.126 ms
64 bytes from localhost (127.0.0.1): icmp_seq=2 ttl=64 time=0.123 ms
64 bytes from localhost (127.0.0.1): icmp_seq=3 ttl=64 time=0.104 ms
[...]
```

Set the number of packets to be sent by ping using the c option. This option causes ping to automatically stop once it has sent the specified number of packets, rather than continuing until stopped manually with Ctrl + C:

ping -c 5 localhost

PING localhost(localhost (::1)) 56 data bytes
64 bytes from localhost (::1): icmp_seq=1 ttl=64 time=0.083 ms
64 bytes from localhost (::1): icmp_seq=2 ttl=64 time=0.083 ms
64 bytes from localhost (::1): icmp_seq=3 ttl=64 time=0.120 ms
64 bytes from localhost (::1): icmp_seq=4 ttl=64 time=0.110 ms
64 bytes from localhost (::1): icmp_seq=5 ttl=64 time=0.112 ms

--- localhost ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4091ms
rtt min/avg/max/mdev = 0.083/0.101/0.120/0.019 ms

Apply a time limit to the ping command using the w option. This option takes a number of seconds as an argument. And, similar to the c option, this option causes ping to automatically stop once the given amount of time has passed:NoteThe w option may not be available for ping on some Unix distributions.

ping -w 5 localhost

PING localhost(localhost (::1)) 56 data bytes
64 bytes from localhost (::1): icmp_seq=1 ttl=64 time=0.131 ms
64 bytes from localhost (::1): icmp_seq=2 ttl=64 time=0.117 ms
64 bytes from localhost (::1): icmp_seq=3 ttl=64 time=0.134 ms
64 bytes from localhost (::1): icmp_seq=4 ttl=64 time=0.122 ms
64 bytes from localhost (::1): icmp_seq=5 ttl=64 time=0.120 ms

--- localhost ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4132ms
rtt min/avg/max/mdev = 0.117/0.124/0.134/0.015 ms

Advanced Options for the ping Command

The options for the ping command covered in this section fit more advanced use cases. They give you even finer-grained control of ping for when you need, for instance, to test a network under specific circumstances.

Specify a network interface for ping to use via the I option, which takes the interface name as an argument. By default, the ping command operates on your system’s default network interface. This option allows you to explicitly specify an interface on systems that have multiple.

This example assumes, for instance, that your system has a network interface called em2 and causes ping to operate through that interface instead of the default:
```
ping -I em2 localhost
```
Control the interval between pings using the i option. The option takes a number of seconds, including fractions (via floating-point numbers). The ping command then sends packets at the designated intervals. By default, the interval is 1, meaning that ping sends one packet per second:
```
ping -i 0.5 localhost
```
Adjust the size of packets sent by ping using the s option. The option takes a number of bytes as its argument. The ping command defaults packet size to 56 bytes, which translates to 64 bytes in the ICMP protocol:
```
ping -s 256 localhost
```
```
PING localhost(localhost (::1)) 256 data bytes
264 bytes from localhost (::1): icmp_seq=1 ttl=64 time=0.119 ms
[...]
```
Flood a network with hundreds of ping requests using the f option. This is a useful option for testing network performance under a heavy load. Be aware that this option requires you to run ping as the root user or use sudo:
```
sudo ping -f localhost
```

Display Options for the ping Command

This section covers a few more useful options for the ping command. The options here are useful when you want to control the way that ping displays results rather than how it gets them.

Limit the display to just the summary statistics by adding the q option to the ping command. This option quiets the lines of packet information and just displays the lines of summary when the ping instance stops:
```
ping -q localhost
```
```
PING localhost(localhost (::1)) 56 data bytes

--- localhost ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2076ms
rtt min/avg/max/mdev = 0.113/0.122/0.129/0.014 ms
```
The -q option can be helpful when sending many packets and wanting only the statistics of their overall performance.

Add timestamps to the beginning of each packet line by adding the D option to your ping command. With this option, each line giving packet information begins with a Unix timestamp representing the time of the packet’s complete transmission.

ping -D localhost

PING localhost(localhost (::1)) 56 data bytes
[1655740627.544608] 64 bytes from localhost (::1): icmp_seq=1 ttl=64 time=0.146 ms
[1655740628.593346] 64 bytes from localhost (::1): icmp_seq=2 ttl=64 time=0.125 ms
[1655740629.617371] 64 bytes from localhost (::1): icmp_seq=3 ttl=64 time=0.117 ms
[...]

Have ping deliver an audible ping effect when receiving a response from the host by using the a option. More than just a preference, such an option can be useful when pinging hosts that are taking a long time to respond. The option allows you to look away and still be alerted when the host has been reached.
```
ping -a localhost
```

Conclusion

This guide has given an in-depth look at the Linux ping command and some of the most useful options it has to offer. With this, you have the tools you need not only to start using the ping command on your Linux system. You also have tools to make the most of it, tools for tuning your network tests more precisely to your needs.

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