[lkml]   [1996]   [Oct]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Ping with a 65510 bytes pack
Alan Cox wrote:
> > Yes it fix the problem. Applied against 2.1.5 rather than 2.0.22.
> > I will provide some dump of this strange icmp packet later.
> This is indeed a combination of a windows 95 bug - apparently fixed in later
> releases and a Linux bug when we construct a packet over 64K long (not valid)
> Unfortunately the ip_send test program I had didnt build a packet that got
> high enough up the stack after reassembly to cause an explosion.
> Fun bug ;). Now perhaps you can get the tcp fixes into the 2.0.24 release
> and the route cache leak fix hey Linus 8)

I've played further with big sized ICMP_ECHO, and found some interesting
behavior of the ping prog. (Mine come from debian 1.1 netbase package).

pinging myself ( give that:

packetsize (-s)

56-24372 work ok
24373-65332 nothing _seems_ to get through
(though i can't put tcpdump on the loopback :)
65333-65464 work ok
65465-65468 really weird, seem to loose some bits, print a warning message
and dump the packet on the screen.
On 2.1.5, i rather get a 'Couldn't get a free page....'
65469 packet too large

On the wire, bheavior seem different, between to linux box
(a 2.1.5 and a 2.0.10, no router, just a hub)

56-48948 work well
48949-65469 ping doesn't give a line of result, though tcpdump see all the
packet coming and going (request *and* reply). Also the LED's on
the hub are riding high every second :) but this is OK.

Any ideas? well, ok this is more a ping soft. problem (except maybe for the
Couldn't get a free page).

Philippe Strauss, CH-1092 Belmont

Email: <>

 \ /
  Last update: 2005-03-22 13:38    [W:0.045 / U:1.068 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site