How to ping IPv6 addresses

The command ping is commonly known as the tool for pinging IP addresses. For example:

$ $ ping 127.0.0.1
PING 127.0.0.1 (127.0.0.1): 56 data bytes
64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=0.066 ms
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.072 ms
^C
--- 127.0.0.1 ping statistics ---
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.066/0.069/0.072/0.003 ms

However, trying to ping an IPv6 address fails:

$ ping ::1
ping: cannot resolve ::1: Unknown host

"Maybe I should enclose the address within square brackets?"

$ ping [::1]
ping: cannot resolve [::1]: Unknown host

Nah, that's required only when IPv6 addresses are used in a URL context.

How to ping IPv6 addresses#

The command for pinging IPv6 address is ping6. Let's ping localhost using its IPv6 address:

$ ping6 ::1
PING6(56=40+8+8 bytes) ::1 --> ::1
16 bytes from ::1, icmp_seq=0 hlim=64 time=0.053 ms
16 bytes from ::1, icmp_seq=1 hlim=64 time=0.120 ms
^C
--- ::1 ping6 statistics ---
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/std-dev = 0.053/0.086/0.120/0.034 ms

Now let's try pinging an external IPv6 address. Let's ping facebook.com's IPv6 address (2a03:2880:f12f:83:face:b00c::25de).

$ ping6 2a03:2880:f12f:83:face:b00c::25de
ping6: UDP connect: No route to host

"ping6: UDP connect: No route to host?"

We will need to specify the network interface. On Macs, it will either be en1 or en0. On Linux, it is very likely eth0.

$ ping6 -I en1 2a03:2880:f12f:83:face:b00c::25de

In case, you get "ping6: sendmsg: No route to host", something in your system or router needs to be configured for IPv6. Once configured, you will be able to ping IPv6 addresses using ping6.

Summary#

To ping IPv6 addresses, use the ping6 command along with the interface option -I. Example: ping -I en1 2a03:2880:f12f:83:face:b00c::25de.