Re: [LARTC] Why 'ping' only succeed in one direction?

From: Mike Fedyk (mfedyk@matchmail.com)
Date: Wed May 30 2001 - 21:25:50 EST


On Tue, May 29, 2001 at 10:53:16PM +0800, shen jing wrote:
> Hi:
>
> I'm using a linux box ( Rh7.1 ) as a router which connect two Solaris2.6

what kernel version?

distribution version doesn't help much.

>
> box.
> The three computer is interconnected by ethernet, each computer has
> only on ethernet adapter.
>
> The following is my network connection :
>
> ----------------------------------- ( Ethernet)
> | || |||
> | || |||
> Sun-1 Linux Sun-2
> 210.32.131.97 192.168.1.1(eth0) 192.168.1.8
> 210.32.131.166(eth0:0)
>

They're all on one ethernet segment, and just different IPs?

> Routing table :
>
> Sun-1: 192.168.1.0/24 ---> 210.32.131.166
> default -----> 210.32.131.2
>

What does "192.168.1.0/24 ---> 210.32.131.166" mean?

> Linux : default---> 210.32.131.2
> ( I add no explicit routing table about the twodirect
> connected network )
>

Bad!

Can your linux box ping each sun box?

Let us see the output of some commands. Install the iproute (so you can run
"ip" as root) package, and give use the output of:

ip route
ip rule
ip address

Send the output of whatever SUN uses to give IP addresses, Routes, etc too.

> Sun-2 : default --> 192.168.1.1
>
> While I exec "ping 192.168.1.8 "on Sun-1, it succeed, with 0% packet
> loss.
>
> But when I exec "ping 210.32.131.97" on Sun-2, the ping always hang
> with no output, when I interrupt it with "Ctl-C', it shows "100% packet
> loss".
>
> I do tcpdump on linux and snoop on Sun to find out what happened, but
> all detailed record shows "ICMP echo requect/reply " has been delivered
> between Sun-1<-->linux, Linux<-->Sun-2
>

It looks like you didn't change the default route to one of the IPs on the
linux box on the SUNs.

> And I can telnet/ftp between Sun-1 & Sun-2.
>
> Is there someone will do me a favor to explain why this happens ? Is
> there any configuration error with my linux box ?
>
Yes.

> Thanks in advance and each word will be highly appreciated.
>

Mike
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