Why "ping6 -I <Interface_name>" is not working in RHEL 7 system?
Environment
- Red Hat Enterprise Linux (RHEL 7)
- IPv6
Issue
ping6
is able to ping via an interface, even if the interface is not havingIPv6
address assigned/configuredping6
is picking other interfaces when specified particular interface using "-I" option when theIPv6
IP is not configured on it.ping6 -I <interface_name>
was working inRHEL6
but not withRHEL7
.
Resolution
-
This issue has been resolved with the release of RHEL 7.4 and with the upgraded version of
iputils
package and with the release of theiputils-20160308-10.el7
package as RHBA-2017:1987 -
Please upgrade the iputils package to at least
iputils-20160308-10.el7
Root Cause
- Code fix has been provided and below are the details
https://github.com/iputils/iputils/commit/fd79cc90c4af117e3fa41466151cdd289e460569
Diagnostic Steps
IPv6
address configured onens9
interface and not on theens10
4: ens9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:00:00-00:00:aa brd ff:ff:ff:ff:ff:ff
inet 10.0.1.1/24 brd 10.0.0.255 scope global dynamic ens9
valid_lft 3054sec preferred_lft 3054sec
inet6 2001:xxxx:xxxx:xx::6/64 scope global
valid_lft forever preferred_lft forever
inet6 fe80::xxxx:xxxx:xxxx:xxxx/64 scope link
valid_lft forever preferred_lft forever
5: ens10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:00:00-00:00:bb brd ff:ff:ff:ff:ff:ff
inet 10.0.0.1/24 brd 10.0.0.255 scope global ens10
valid_lft forever preferred_lft forever
inet 10.0.2.3/24 brd 10.0.2.255 scope global ens10
valid_lft forever preferred_lft forever
- When specifying the interface which is not having
IPv6
address,ping6
is still working as it is picking the other interface (ens9
) which is havingIPv6
address
# ping6 -I ens10 2001:xxxx:xxxx:xx::4
PING 2001:xxxx:xxxx:xx::4(2001:xxxx:xxxx:xx::4) 56 data bytes
64 bytes from 2001:xxxx:xxxx:xx::4: icmp_seq=1 ttl=64 time=1.35 ms
64 bytes from 2001:xxxx:xxxx:xx::4: icmp_seq=2 ttl=64 time=1.30 ms
^C
--- 2001:xxxx:xxxx:xx::4 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 1.308/1.329/1.351/0.042 ms
- Once the system is upgraded to
iputils-20160308-10.el7
, theping6
is failing if theIPv6
address is not configured or is disabled on the interface
# rpm -qa | grep -i iputils
iputils-20160308-10.el7.x86_64
# ping6 -I ens10 2001:xxxx:xxxx:xx::4
ping6: Warning: source address might be selected on device other than ens10.
PING 2001:xxxx:xxxx:xx::4(2001:xxxx:xxxx:xx::4) from 2001:xxxx:xxxx:xx::6 ens10: 56 data bytes
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
^C
--- 2001:xxxx:xxxx:xx::4 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 1999ms
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