Ubuntu
iputils package

  1. Bug #1775891
  2. Comment #0

Comment 0 for bug 1775891

Revision history for this message
psl (slansky) wrote :

ping6 utility, iputils-s20121221, Ubuntu 16.04.4 amd64

IPv6 address can have extension with local interface. It is required to ping link-level IPv6 addresses (fe80::/10).

Example,

ping6 fails, OS doesn't know where to route packets

user@test$ ping6 -c1 fe80::87f4:81fa:b481:d781
connect: Invalid argument

network interface is specified, ping6 works:

user@test$ ping6 -c1 fe80::87f4:81fa:b481:d781%enp4s0
PING fe80::87f4:81fa:b481:d781%enp4s0(fe80::87f4:81fa:b481:d781) 56 data bytes
64 bytes from fe80::87f4:81fa:b481:d781: icmp_seq=1 ttl=64 time=0.461 ms

--- fe80::87f4:81fa:b481:d781%enp4s0 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.461/0.461/0.461/0.000 ms

Ping loopback, it works

user@test$ ping6 -c1 ::1
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.039 ms
--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.039/0.039/0.039/0.000 ms

But when I add %lo, ping6 cannot handle it.... This is the issue I want to report.

user@test$ ping6 -c1 ::1%lo
unknown host

Other example with real IPv6 address

user@test$ ping6 -c1 2001:470:6e:66::2
PING 2001:470:6e:66::2(2001:470:6e:66::2) 56 data bytes
64 bytes from 2001:470:6e:66::2: icmp_seq=1 ttl=64 time=0.054 ms

--- 2001:470:6e:66::2 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.054/0.054/0.054/0.000 ms

user@test$ ping6 -c1 2001:470:6e:66::2%sit1
unknown host

BTW, CURL can do it...

user@test$ curl http://[::1%lo]/test.htm
<html><body>TEST</body></html>

user@test$ curl http://[2001:470:6e:66::2%sit1]/test.html
curl: (7) Failed to connect to 2001:470:6e:66::2 port 80: Connection refused

Yes, curl fails in this case but there is no http server configured at that IPv6 address... Important point is it tries to connect. Here is a proof:

user@test$ curl http://[2001:470:6e:66::2%sit1]:22/test.html
SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.4
Protocol mismatch.
curl: (56) Recv failure: Connection reset by peer