Cannot ping any other host, but networks fine???

Cannot ping any other host, but networks fine???

Post by Keith Sor » Fri, 07 Jun 2002 21:32:47



Hi,

I am struggling with something that must have a very simple solution.
I am using Samba on RH 7.1 with all MSWin9x clients.

Problem:

I cannot ping my linux server or any other client on my ethernet
network.

Facts:

1. Samba works just fine.
2. I can use SSH (putty) to contact the linux.
3. Ping is able to resolve host names into IP addresses. I.e. if I
ping a non-existent host, it responds that the host does not exist.
4. While logged onto the server I can ping the server itself with no
problem.
5. Ping worked just fine when I installed RH 7.1, but something
happened along the way that "broke" it. I have no idea what I did to
break it.

Possible result of the same problem :
I have VERY LONG times (1-2 minutes for a short email) when I SMTP
from Win98 client machine to the linux sendmail, but it does
eventually get through.

Any ideas? I am pretty new at this.

Keith

 
 
 

Cannot ping any other host, but networks fine???

Post by Joerg Morbitze » Fri, 07 Jun 2002 22:59:13



: Hi,
:
: I am struggling with something that must have a very simple solution.
: I am using Samba on RH 7.1 with all MSWin9x clients.
:
: Problem:
:
: I cannot ping my linux server or any other client on my ethernet
: network.
:
: Facts:
:
: 1. Samba works just fine.
: 2. I can use SSH (putty) to contact the linux.
: 3. Ping is able to resolve host names into IP addresses. I.e. if I
: ping a non-existent host, it responds that the host does not exist.
: 4. While logged onto the server I can ping the server itself with no
: problem.
: 5. Ping worked just fine when I installed RH 7.1, but something
: happened along the way that "broke" it. I have no idea what I did to
: break it.
:
: Possible result of the same problem :
: I have VERY LONG times (1-2 minutes for a short email) when I SMTP
: from Win98 client machine to the linux sendmail, but it does
: eventually get through.
:
: Any ideas? I am pretty new at this.

Sounds really strange. As you said the networking in general works,
otherwise you wouldn't be able to login using putty. But this (like samba)
is using the tcp protocol, ping or traceroute uses the icmp procotocl.
Perhaps, for some reason, you installed iptables on your RH box dropping
any icmp packets? If you are in a secure environment try to disable your
INPUT rules by

        iptables -P INPUT ACCEPT
        iptables -F INPUT
        iptables -P OUTPUT ACCEPT
        iptables -F OUTPUT
        iptables -P FORWARD ACCEPT
        iptables -F FORWARD

These commands shut down basically the firewall rules completely. Does
ping still don't work?

Regards, Joerg.

 
 
 

Cannot ping any other host, but networks fine???

Post by M. Buchenried » Sat, 08 Jun 2002 00:19:11


[...]

Quote:>1. Samba works just fine.
>2. I can use SSH (putty) to contact the linux.
>3. Ping is able to resolve host names into IP addresses. I.e. if I
>ping a non-existent host, it responds that the host does not exist.
>4. While logged onto the server I can ping the server itself with no
>problem.
>5. Ping worked just fine when I installed RH 7.1, but something
>happened along the way that "broke" it. I have no idea what I did to
>break it.

You have a firewall in place.

Quote:>Possible result of the same problem :
>I have VERY LONG times (1-2 minutes for a short email) when I SMTP
>from Win98 client machine to the linux sendmail, but it does
>eventually get through.

This is a problem with rDNS requests. Setup a local name server.

Michael
--

          Lumber Cartel Unit #456 (TINLC) & Official Netscum
    Note: If you want me to send you email, don't munge your address.

 
 
 

Cannot ping any other host, but networks fine???

Post by Keith Sor » Sat, 08 Jun 2002 09:35:40




> : Hi,
> :
> : I am struggling with something that must have a very simple solution.
> : I am using Samba on RH 7.1 with all MSWin9x clients.
> :
> : Problem:
> :
> : I cannot ping my linux server or any other client on my ethernet
> : network.
> :
> : Facts:
> :
> : 1. Samba works just fine.
> : 2. I can use SSH (putty) to contact the linux.
> : 3. Ping is able to resolve host names into IP addresses. I.e. if I
> : ping a non-existent host, it responds that the host does not exist.
> : 4. While logged onto the server I can ping the server itself with no
> : problem.
> : 5. Ping worked just fine when I installed RH 7.1, but something
> : happened along the way that "broke" it. I have no idea what I did to
> : break it.
> :
> : Possible result of the same problem :
> : I have VERY LONG times (1-2 minutes for a short email) when I SMTP
> : from Win98 client machine to the linux sendmail, but it does
> : eventually get through.
> :
> : Any ideas? I am pretty new at this.

> Sounds really strange. As you said the networking in general works,
> otherwise you wouldn't be able to login using putty. But this (like samba)
> is using the tcp protocol, ping or traceroute uses the icmp procotocl.
> Perhaps, for some reason, you installed iptables on your RH box dropping
> any icmp packets? If you are in a secure environment try to disable your
> INPUT rules by

>    iptables -P INPUT ACCEPT
>    iptables -F INPUT
>    iptables -P OUTPUT ACCEPT
>    iptables -F OUTPUT
>    iptables -P FORWARD ACCEPT
>    iptables -F FORWARD

> These commands shut down basically the firewall rules completely. Does
> ping still don't work?

> Regards, Joerg.

Joerg,

When I attempt any of the iptables commands, I get an error
...iptables.o device or resource busy
etc.

Is it possible that I need to completely disable the iptables daemon?
We are running an internal network, only with dialup connection to the
internet. We do not need a high security environment at this time.

Keith

 
 
 

Cannot ping any other host, but networks fine???

Post by Joerg Morbitze » Sat, 08 Jun 2002 14:52:58


: > Sounds really strange. As you said the networking in general works,
: > otherwise you wouldn't be able to login using putty. But this (like samba)
: > is using the tcp protocol, ping or traceroute uses the icmp procotocl.
: > Perhaps, for some reason, you installed iptables on your RH box dropping
: > any icmp packets? If you are in a secure environment try to disable your
: > INPUT rules by
: >
: >  iptables -P INPUT ACCEPT
: >  iptables -F INPUT
: >  iptables -P OUTPUT ACCEPT
: >  iptables -F OUTPUT
: >  iptables -P FORWARD ACCEPT
: >  iptables -F FORWARD
: >
: > These commands shut down basically the firewall rules completely. Does
: > ping still don't work?
: >
: > Regards, Joerg.
:
: Joerg,
:
: When I attempt any of the iptables commands, I get an error
: ...iptables.o device or resource busy
: etc.
:
: Is it possible that I need to completely disable the iptables daemon?
: We are running an internal network, only with dialup connection to the
: internet. We do not need a high security environment at this time.
There is no daemon or something like this. The only way to completely
disable it is either setting up the commands above or to disable it during
kernel compilation.

Concerning your error message I found another news, please look
at this side, this might help you stopping your firewall rulez:

http://lists.samba.org/pipermail/netfilter/2001-July/013080.html

Regards, Joerg.

 
 
 

1. Strange network problems - pings to host are fine, pings from host fail

Sorry for the long post - I've tried to outline the symptoms of my
problem, and what I've tried to fix it.

I'm having some networking problems with a PC running an old version of
Red Hat (kernel 2.2).  The PC came with a machine we have bought
second-hand - as far as I know, everything was working before the
machine was moved to our company.

To keep things simple, we have the Red Hat machine connected to a
Windows XP machine that came with it, with only a simple switch in
between.  Each machine is set up with a fixed IP address on the same
network.

 From the XP machine, I can ping the Red Hat machine reliably and
quickly.  From the Red Hat machine, pings to the XP machine /generally/
fail - typically there are about 80%-90% failures.  Those pings that
don't fail, are fast (reply time about 1 ms).  On the XP machine, it's
easy to see the packet counters showing packets in and replies out.  On
the Red Hat machine, ifconfig shows similar packet rx and tx counts, and
zero error counts.

arping to the XP machine from the Red Hat machine is reliable and fast.

When we try a browser on the XP machine and address the web server on
the Red Hat host, there is generally a long pause (perhaps minutes),
then suddenly the page appears.

We have tried using another Linux box in place of the original XP
machine, with the same results from the Red Hat system.

We have tried replacing the cables and switch, with no effect - given
that arpings are working perfectly it's hard to see how it could be a
hardware problem.

I'm not very familiar with Red Hat or a 2.2 kernel (my experience is
mostly with Debian and related distros, and with 2.4 and 2.6 kernels).
But "ipchains -L" shows no firewalling (everything accepted), "ifconfig"
and "route -n" have the expected setup, and I could not stop anything
unexpected with "sysctrl".

One of my colleagues will try a different network card this evening.

Any ideas or tips would be much appreciated.  We've tried pretty much
every sensible idea we can think of, so I'm ready to listen to any crazy
or unlikely tricks.

mvh.,

David

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