Some services working but can't ping (not ping-able)

Some services working but can't ping (not ping-able)

Post by Micah Ellio » Sat, 06 Dec 2003 01:59:58



Hello,
I'm trying to understand why (from anywhere nonlocal) I can't ping my
redhat 7.x machine that is sitting at my home on the net fully exposed (no
firewall, no router, ...). Other services such as ssh and apache are
accessible. Being a networking moron I probably missed something very
simple but it's just not obvious to me. Any help is greatly appreciated.

Background:
- There is no firewall (no ipchains/iptables running)
- No protection in place I'm aware of (hosts.deny is empty)
- I am stuck with a dynamic IP so presently only attempting access via
    IP address
- nslookup shows my IP as 123-123-123-123.client.attbi.com
- ifconfig shows my IP as 123.123.123.123 (so consistent with nslookup)

Good:
- From anywhere I can view my website (at
    http://123.123.123.123/~myacct/index.html) which is hosted on this
    machine via apache
- From anywhere I can ssh into this machine (ssh -l myacct 123.123.123.123)
- From the machine I can browse the net, send mail, etc

Bad (help!):
- From anywhere I can't ping 123.123.123.123
- From anywhere (nonlocal) I cannot send mail to accounts on this machine
    but I figure it might be due to this ping issue. But maybe this is
    because of name resolution (??). Shouldn't I be able to send mail to


--
Micah

 
 
 

Some services working but can't ping (not ping-able)

Post by Carsten Kelle » Sat, 06 Dec 2003 19:47:55



Quote:> Hello,
> I'm trying to understand why (from anywhere nonlocal) I can't ping my
> redhat 7.x machine that is sitting at my home on the net fully exposed (no
> firewall, no router, ...). Other services such as ssh and apache are
> accessible. Being a networking moron I probably missed something very
> simple but it's just not obvious to me. Any help is greatly appreciated.

Are you sure your ISP doesn't block ICMP and maybe SMTP? What happens when
you ping your machine? Does the packets reach it and maybe get lost on the
way back (tcpdump with the right parameters should give you an idea)?

Keller

 
 
 

1. nslookup works, ping #'s works, ping domain fails?

I just upgraded a RH4.2 box to RH 5.0. I can ping ip numbers but when I try
to use a domain name, it can't be resolved


ping: unknown host teleport.com

When I try nslookup, it resolves the number right away.


Default Server:  c3p0.mesd.k12.or.us
Address:  198.236.68.21

Server:  c3p0.mesd.k12.or.us
Address:  198.236.68.21

Name:    teleport.com
Addresses:  192.108.254.12, 192.108.254.10

If I just ping the IP # it works fine.


PING 192.108.254.12 (192.108.254.12): 56 data bytes
64 bytes from 192.108.254.12: icmp_seq=0 ttl=244 time=53.0 ms
64 bytes from 192.108.254.12: icmp_seq=1 ttl=244 time=44.8 ms

I have other RH5 linux boxes on our network and they are working just fine.
This is the only one giving me a headache.

Where should I go from here?

;-) Paul

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