topic Re: Linux droppin ping packets in Operating System - Linux

Linux droppin ping packets

LucianoCarvalho — Fri, 09 Aug 2002 17:06:34 GMT

Hi Guys. I'm having problems with my linux machine. When I issue a ping to linux's ip or hostname, I recieve successfully 5 replies. After that the PC starts to receive one "requst timed out" and two successfully replies.
Runing 100MB full duplex

Anyone have idea???

Re: Linux droppin ping packets

U.SivaKumar_2 — Sat, 10 Aug 2002 05:01:58 GMT

Hi,
Does your swith or hub supports 100Mbps full-duplex ?.
Try pinging to the server ip address from the same server ?.
Does the same problem occur ?. If yes , you
may have change the network card and see. If no
the problem may be with the network cable or network devices like switch or hub .

regards,
U.SivaKumar

Re: Linux droppin ping packets

I_M — Sat, 10 Aug 2002 05:11:00 GMT

Hi

When you do network trouble shoot, you have many things to check.

1) change switch or hub port
2) disable auto-negotiation and set fixed speed
3) change cable (CAT5?)
4) change HUB or SWITCH
5) change NIC
6) change ping destination.

Remember, change ONLY one at a time. Otherwise you will lost.

Good luck

Re: Linux droppin ping packets

Kodjo Agbenu — Sun, 11 Aug 2002 15:25:48 GMT

Hello Luciano,

In the past I had a similar problem with a 3com LAN card. The problem came from using the wrong driver. The one automatically detected and configured during RedHat install was not the good one.

With the wrong driver I could work normally with the machine, telnet and FTP, but the ping sometimes failed and firewall features (ipchains) gave random results.
After changing the driver, everything became normal.

Good luck.

Kodjo

Re: Linux droppin ping packets

Ron Kinner — Mon, 12 Aug 2002 15:39:29 GMT

Since this seems to be a regular pattern that you are seeing I think it may be a security feature that you are seeing. Cisco router's do something similar but they start dropping one out of three right away. There is a line in the RFC which suggests that a machine do this in order to avoid being overrun by a ping attack.

http://www.freesoft.org/CIE/RFC/1812/74.htm

Ron

Re: Linux droppin ping packets

LucianoCarvalho — Tue, 13 Aug 2002 16:33:55 GMT

Hi guys..
It was realy a security feature as Ron said. That feature can be configured in /proc/sys/net/ipv4/icmp_echoreply_rate. I don't know if it is configured in seconds or milliseconds, but if you want the replies to be sent at any rate this file must contain a value of 0.

Thanks a lot everyone.