need help ping/traceroute problems and more...

need help ping/traceroute problems and more...

Post by cmei.. » Mon, 08 Nov 1999 04:00:00



We're running linux with the 2.0.38 kernel, using a D-Link NE2000
compatible ISA network card.  We're connected to a Cisco 2500 series
router on a frame relay connection.  We're not running a firewall.

We can't ping or traceroute anywhere, not even the localhost.  It's like
all icmp traffic is being blocked.  Everything other than icmp
connections
to the internet and the localhost such as telnet, mail, etc, work just
fine.  I've tried upgrading the kernel and that didn't fix it.  We've
also
tried changing out the network card, and that didn't help either.  I
also
haven't been able to get tcpdump to work, so I'm not sure how to
diagnose
it from here.  We tried bringing the system down to single user mode
with
nothing but networking started, to see if perhaps something else was
interfering with it but no luck there either.

This just started happening one day a while back for no apparent reason.
No changes had been made to the system that we're aware of when it
started.

Please e-mail me any suggestions you might have.
Thanks so much,

Claus

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need help ping/traceroute problems and more...

Post by Ken Pizzi » Mon, 15 Nov 1999 04:00:00



>We can't ping or traceroute anywhere, not even the localhost.
>It's like all icmp traffic is being blocked.  Everything other
>than icmp connections to the internet and the localhost such as
>telnet, mail, etc, work just fine.

Sounds like the ping and traceroute executables are not
installed correctly --- they either need to be s-uid to
root, or to not s-uid at all and be run only by root.

Quote:>  We tried bringing the system down to single user mode with nothing
>but networking started, to see if perhaps something else was
>interfering with it but no luck there either.

Presumably this means that you did test while running as the
super user; this suggests that someone (either accidentally
or as a prank) did a chown on these programs to a non-root
user; try (as root):
  chown root `type -path ping traceroute`
  chmod u+s,go-w `type -path ping traceroute`
  ping -c 1 localhost
  traceroute localhost

                --Ken Pizzini

 
 
 

1. need help ping/traceroute problems

Hi,

I tried to use ping and traceroute, in my unix account and it did not
work. It retrieved the IP address of the name I typed in but it did not
receive any packages from any server.
The same with any server I tried.
But, when I tried to telnet into these servers, it did work like a
charme.
I mailed my system admin but they do not know what could cause it
either.It seems like that ICMP packets are being blocked, but they are
not running a firewall.

I would be very thankful for suggestions what could cause this problem.

Thank you very much. Please e-mail me.

Claus

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