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

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

Post by micah.d.el » 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://www.yqcomputer.com/ ~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
XXXX@XXXXX.COM , or possibly even
myacct@[123.123.123.123] ?

--
Micah
 
 
 

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

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


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