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Bug 1172084 - inconsistent ping behaviour and hang with too large packet size
Summary: inconsistent ping behaviour and hang with too large packet size
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: iputils
Version: 7.1
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Jan Synacek
QA Contact: Robin Hack
URL:
Whiteboard:
Depends On:
Blocks: 1289485 1295396 1313485
TreeView+ depends on / blocked
 
Reported: 2014-12-09 11:21 UTC by Karel Volný
Modified: 2016-11-04 00:11 UTC (History)
2 users (show)

Fixed In Version: iputils-20160308-3.el7
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2016-11-04 00:11:38 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHEA-2016:2185 0 normal SHIPPED_LIVE iputils bug fix update 2016-11-03 13:18:16 UTC

Description Karel Volný 2014-12-09 11:21:10 UTC 
Description of problem:
The manpage of ping doesn't list maximum allowed packet size. Experimenting with it to test fragmentation, I've found that ping behaves inconsistently. It even hangs under some circumstances ...

Version-Release number of selected component (if applicable):
iputils-20121221-6.el7.x86_64

How reproducible:
always

Steps to Reproduce:
1. ping -c 1 -s 65507 localhost ; echo $?
2. ping -c 1 -s 65508 localhost ; echo $?
3. ping -c 1 -s 65528 localhost ; echo $?
4. ping -c 1 -s 65529 localhost ; echo $?

Actual results:
1.
PING localhost (127.0.0.1) 65507(65535) bytes of data.
65515 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.539 ms

--- localhost ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.539/0.539/0.539/0.000 ms

0


2.
WARNING: packet size 65508 is too large. Maximum is 65507
PING localhost (127.0.0.1) 65508(65536) bytes of data.
ping: local error: Message too long, mtu=10000

--- localhost ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

1


3.
WARNING: packet size 65528 is too large. Maximum is 65507
PING localhost (127.0.0.1) 65528(65556) bytes of data.
ping: sendmsg: Message too long
^C
--- localhost ping statistics ---
1 packets transmitted, 0 received, 100% packet loss, time 0ms

1


^ ping hangs in this case, note ctrl+c sent!


4.
ping: packet size too large: 65529
2


Expected results:
1.
PING localhost (127.0.0.1) 65507(65535) bytes of data.
65515 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.539 ms

--- localhost ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.539/0.539/0.539/0.000 ms

0


2.
ERROR: packet size 65508 is too large. Maximum is 65507
2


3.
ERROR: packet size 65528 is too large. Maximum is 65507
2


4.
ERROR: packet size 65529 is too large. Maximum is 65507
2


Additional info:
It'd be nice to mention the maximum size within the manpage too, if that's a constant. If it is system dependent, then at least some clue how the maximum size is computed would be useful.
Comment 3 Jan Synacek 2016-03-01 09:17:21 UTC 
The minor inconsistencies and the hang will be fixed by bz#1273336. I don't see a reason why the maximum size should be documented in the man page though, since the MTU and the ICMP header size of the given network are always known...

Behavior with the new version:

$ ping -c 1 -s 65507 localhost ; echo $?
PING localhost(localhost (::1)) 65507 data bytes
65515 bytes from localhost (::1): icmp_seq=1 ttl=64 time=0.085 ms

--- localhost ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.085/0.085/0.085/0.000 ms
0

$ ping -c 1 -s 65508 localhost ; echo $?
PING localhost(localhost (::1)) 65508 data bytes
65516 bytes from localhost (::1): icmp_seq=1 ttl=64 time=0.067 ms

--- localhost ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.067/0.067/0.067/0.000 ms
0

$ ping -c 1 -s 65528 localhost ; echo $?
PING localhost(localhost (::1)) 65528 data bytes
ping: local error: Message too long, mtu=65536

--- localhost ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

1

$ ping -c 1 -s 65529 localhost ; echo $?
PING localhost(localhost (::1)) 65529 data bytes
ping: local error: Message too long, mtu=65536

--- localhost ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

1
Comment 10 Jan Synacek 2016-04-20 07:59:04 UTC 
Submitted upstream: https://github.com/iputils/iputils/pull/49
Comment 11 Jan Synacek 2016-04-25 10:03:30 UTC 
I just realize that this bug shouldn't be in POST, since it's still awaiting a review upstream...
Comment 16 errata-xmlrpc 2016-11-04 00:11:38 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHEA-2016-2185.html
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