ping/traceroute problems

ping/traceroute problems

Post by cmei.. » Sun, 07 Nov 1999 04:00:00



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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Before you buy.

 
 
 

ping/traceroute problems

Post by Ken Pizzi » Sun, 07 Nov 1999 04:00:00



>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.

Firewalls and NAT (network address translation) are two common
obsticals to "ping" (and other ICMP usages) working.  (Traceroute
actually sends UDP packets out, but listens for specific ICMP
errors in order to do its task.)

Quote:>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.

Is there any firewall (or even just packet filtering) or address
translation going on anywhere between your machine and the
remote machine?  (One other thing is that ICMP requires root
priveleges, but it is not uncommon for ping and traceroute to be
s-uid root for this reason, and you should be getting an error
message back from ping/traceroute if this were the problem.)

                --Ken Pizzini

 
 
 

ping/traceroute problems

Post by Carlo Hogevee » Mon, 08 Nov 1999 04:00:00


This might be the same problem I am having, but your e-mail is
ambigous at this point.

When I try to ftp to a machine where no one is working, then ftp fails
to connect, but after I have opened a telnet session on the machine
ftp suddenly works too. A colleague reported the same behaviour
with ping.

It seems like ftp and ping are not capable of awakening the remote
machine, but telnet is.

Alas, our network administrator gives the problem low priority
because of the manual workaround.

I would very much like to know the solution to this problem too.

Carlo

: 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
:
:
:
: Sent via Deja.com http://www.deja.com/
: Before you buy.

 
 
 

1. need help ping/traceroute problems and more...

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

Sent via Deja.com http://www.deja.com/
Before you buy.

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