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One of my websites is inaccessible via certain ISPs. I ran a trace route and I can see where it stops. Looks like it's owned by the ISP. Is there anything I can do about this? Can the hosting provider do anything? Do I have to call the ISP and ask if they can/will do anything about it?

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ISPs will commonly block traceroutes when it hits a major router. Doesn't mean that the data flow actually stops there though. – Lawrence Dec 19 '13 at 6:53
@Lawrence: Ah...well, the site is inaccessible via browsers as well. Would it not be a reasonable assumption that that same server is also blocking HTTP traffic? Or is it a coincidence that there happens to be a server a long the chain that's blocking trace routes, and a separate server blocking HTTP? – mpen Dec 19 '13 at 21:10
Coincidence. If you did a traceroute to any other site that did work, chances are the trace would stop at the exact same point. – Lawrence Dec 20 '13 at 1:41
@Lawrence: Well, now that the site's been moved to a new server and it works again... I can do that. Trace route goes all the way through to it now. Doesn't look like it's hitting that same node I guess that doesn't really answer anything. – mpen Dec 20 '13 at 21:40
up vote 2 down vote accepted

There is, unfortunately no easy answer to the problem, and the answer is very much "it depends" - basically it depends on your ISP, the provider thats blocking the traffic and the reason for the block.

A good first step is to communicate reasonable detailed information to both your ISP and your hosting provider - Your hosting provider is paying for a service (and you are paying them), so they have some leverage and probably SLA's and the like. Of-course, the more budget the host the less this helps you.

You do want to try and do "traceroutes" in both directions to see whats going on and provide them to the provider - this is the minimum information they need. Using MTR is generally a better solution as it shows packet loss as well.

That said, it may be easier just to migrate the site to a different ISP - or get another IP address from your current provider which is not blocked - beware of "bad neighbourhoods" though.

Another "work-arround" (which may defeat the purpose) might be to put in a reverse proxy at another site and then pointing the DNS to it and proxying to the real provider. Its probably overkill though, but could be useful if you need to move the site, or to circumvent certain reachability issues.

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MTR? "migrate the site to a different ISP" -- you mean hosting provider? ISP is the service our clients/visitors use, and is out of our control. Anyway, we got our host to move us to a different server, and that appears to have resolved the problem. Something, somewhere, must have been blocking any connections to that one server. – mpen Dec 19 '13 at 21:14
@Mark - MTR is an advanced traceroute program which shows hops, packet loss etc. A hosting provider is a type of ISP (They provide Internet Services). Thank you for accepting my answer ! – davidgo Dec 20 '13 at 0:54

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