Re: [gentoo-user] Can't ping remote system

[Alan McKinnon]

On 01/09/2013 20:50, Grant wrote:
>>>>>>>>>> My laptop can't ping my remote system but it can ping others
>>>>>>>>>> (google.com, yahoo.com, etc).  I've tried disabling my firewall on
>>>>>>>>>> both ends with '/etc/init.d/shorewall stop && shorewall clear'.  Could
>>>>>>>>>> my AT&T business ADSL connection on the remote system be blocking
>>>>>>>>>> inbound pings?
>>>>>
>>>>> I did 'traceroute -w 30 -I ip-address' several times and the last IP
>>>>> displayed is always the same.  I looked it up and it's an AT&T IP
>>>>> supposedly located about 1500 miles from my machine which is also on
>>>>> an AT&T connection.  Does this tell me anything?
>>>>
>>>> Yes, it tells you that all hops up to that point at least respond to
>>>> the kinds of icmp packets traceroute uses. The first hop that fails to
>>>> answer isn't answering.
>>>>
>>>> You are looking for possible reasons why icmp might not be working out
>>>> properly - that router is your first suspect. Admittedly, it might be
>>>> blocking traceroute pings and still allow the responses you seek, but
>>>> you have to start somewhere :-)
>>>
>>> So the culprit is the first IP that should appear in the list but
>>> doesn't?  If so, how is that helpful since it's not displayed?
>>
>> This is where it gets tricky. You identify the last router in the list
>> for which you have an address or name, and contact the NOC team for that
>> organization. Ask them for the next hop in routing for the destination
>> address you are trying to ping and hope that they will be kind enough to
>> help you out.
>
> Oh man that's funny.  Really?  Let's say they do pass along the info.
> Then I hunt down contact info for the culprit router based on its IP
> and tell them their stuff isn't working and hope they fix it?
> Actually, since the last IP displayed is from AT&T and my server's ISP
> is AT&T, I suppose it's extremely likely that the culprit is either an
> AT&T router somewhere or my own server and I could find out by calling
> AT&T.


Well, I did try to convey a sense of what it sometimes takes to deal
with such things. Usually your ISP deals with it for you and you'd be
amazed how often they pick up the phone to do exactly what I described.

But I think this is getting OT to your actual problem. AT&T's routers
are probably not the cause, it only came up because of issues with
pinging things, and that is not what you are trying to solve.

-- 
Alan McKinnon
alan.mckinnon@×××××.com