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neil0311

join:2005-07-24
Marietta, GA

Inaccessible sites....what is likely cause?

I have had issues with two specific sites not being accessible. This has been the case with two separate WiFi routers and more than one system/device (with different OS's). I'll be able to access the sites in question (which are mainstream sites and I am not doing anything against their rules), and then suddenly I cannot access them, ping them, or tracert to them. Others confirm they can connect fine during my inability to connect, and I can connect with my wireless carrier on my phone, so the sites are up.

What is baffling is that if I clone a different MAC address to the router, which then gets me a new IP assigned by Comcast, I can connect again, almost as if the IP is the issue. Because of this, I have contacted the sites to be sure my IP wasn't getting blocked for some reason, either intentionally or unintentionally....and it's not, nor is my user for either site suspended or otherwise blocked. One site is a mainstream user forum and the other is an online business where I have purchased many items.

Anyone know what could be the issue? Does Comcast have routing issues like that where one IP may have issues connecting to specific sites while another is just fine? It's baffling to me, so just looking for any information about possible causes and what I can do on my end, if the issue could be specific to my setup.



baineschile
2600 ways to live
Premium
join:2008-05-10
Sterling Heights, MI

Whats the sites? Run a tracert on them, and post the results here.

I will try for you as well, to see if its a backbone routing issue


neil0311

join:2005-07-24
Marietta, GA

said by baineschile:

Whats the sites? Run a tracert on them, and post the results here.

I will try for you as well, to see if its a backbone routing issue

Nothing to post since it currently works. As stated, I changed the MAC address on my router and acquired a new IP. That will usually do the trick, but in the past only for a while.

I'm trying to understand more about potential causes on Comcast's side. When I've called them, they tell me all is well and it must be the site blocking my IP. The site says nothing is being blocked.

All I know for sure is that changing the MAC address on my router fixes the problem, at least for a while.


pflog
Bueller? Bueller?
Premium,MVM
join:2001-09-01
El Dorado Hills, CA
kudos:3

We can't possibly help without additional data, including the specific sites you're having problems with (and what IP(s) the hostnames resolve to) and traceroutes to them.

I'm not sure why you refer to them as "mainstream" but won't mention the actual hosts in question.
--
"I drank what?" -Socrates


neil0311

join:2005-07-24
Marietta, GA

said by pflog:

We can't possibly help without additional data, including the specific sites you're having problems with (and what IP(s) the hostnames resolve to) and traceroutes to them.

I'm not sure why you refer to them as "mainstream" but won't mention the actual hosts in question.

Did I say I won't post the names of the sites? You're making it sound like I'm trying to hide them. I responded that the problem isn't currently happening, so tracert shows a normal connection and there's no point in posting a tracert.

My question is about issues that are possible on the Comcast side, so not sure why the specific sites matter, but if you're dying to know...they're city-data.com and pcaviator.com. This is less about the sites than about why my connection to them is affected when I change my MAC address.


pflog
Bueller? Bueller?
Premium,MVM
join:2001-09-01
El Dorado Hills, CA
kudos:3

said by neil0311:

said by pflog:

We can't possibly help without additional data, including the specific sites you're having problems with (and what IP(s) the hostnames resolve to) and traceroutes to them.

I'm not sure why you refer to them as "mainstream" but won't mention the actual hosts in question.

Did I say I won't post the names of the sites? You're making it sound like I'm trying to hide them. I responded that the problem isn't currently happening, so tracert shows a normal connection and there's no point in posting a tracert.

My question is about issues that are possible on the Comcast side, so not sure why the specific sites matter, but if you're dying to know...they're city-data.com and pcaviator.com. This is less about the sites than about why my connection to them is affected when I change my MAC address.

When you change your MAC address, you will get a new IP address. That can change routing and more importantly can then allow you to bypass filtering or firewall rules for the destination sites in question.
--
"I drank what?" -Socrates


pflog
Bueller? Bueller?
Premium,MVM
join:2001-09-01
El Dorado Hills, CA
kudos:3

1 recommendation

reply to neil0311

It would be useful to see your traceroutes to these two hosts NOW while it's working, too, to compare against when you start having problems again.
--
"I drank what?" -Socrates


neil0311

join:2005-07-24
Marietta, GA
reply to pflog

said by pflog:

When you change your MAC address, you will get a new IP address. That can change routing and more importantly can then allow you to bypass filtering or firewall rules for the destination sites in question.

Yup, all info that I knew before I posted. As mentioned, queries to both sites were answered, and neither has implemented any IP filtering or other rules that would be blocking me. My interactions with these sites is limited to benign posts and purchases.

I was hoping that others have had the same type of thing happen and might have a better understanding. Either these sites are lying to me and are blocking my specific IP for some totally unknown reason, or my guess is that it could be a range of IPs being blocked by a provider downstream.


plencnerb
Premium
join:2000-09-25
Carpentersville, IL
kudos:3
reply to neil0311

To go along with what pflog See Profile said, if you post a trace file when you cannot get to them, we may be able to figure out why from the trace route. Also doing things like a ping test, and a dns lookup by name and by IP could also point to potential problems.

Also, a little more information on "Not being accessible" could be helpful. Does the page time out, give an error message, or just fail to load (no error message, but you don't get the page either). All of that information can help us figure out what is going on, and potentially help solve your problem.

Sure it works now, and you think it was because of your IP that you were assigned. But, what if it was not? What if tomorrow the sites also stop working again for you? You going to clone the MAC again, and get a 3rd IP?

My suggestion to you would be to put things back so they fail. Then, run the following commands and let us know the results.

• tracert city-data.com
• tracert pcaviator.com
• nslookup city-data.com
• nslookup pcaviator.com

Finally, run two more nslookup commands, using the IP that comes back from the nslookup of the site name. In theory, they should match if the RDNS records are set right. Even if they don't, its OK, but it could point to a DNS problem somewhere.

--Brian
--
============================
--Brian Plencner

E-Mail: CoasterBrian72Cancer@gmail.com
Note: Kill Cancer to Reply via e-mail


neil0311

join:2005-07-24
Marietta, GA
reply to pflog

said by pflog:

It would be useful to see your traceroutes to these two hosts NOW while it's working, too, to compare against when you start having problems again.

And I've done that and they look the same, except the traffic stops a couple of hops before the destination, which is why I was guessing that some kind of IP range was blocked of which my IP belonged. I was hoping others may also have experienced.


plencnerb
Premium
join:2000-09-25
Carpentersville, IL
kudos:3

1 recommendation

said by neil0311:

said by pflog:

It would be useful to see your traceroutes to these two hosts NOW while it's working, too, to compare against when you start having problems again.

And I've done that and they look the same, except the traffic stops a couple of hops before the destination, which is why I was guessing that some kind of IP range was blocked of which my IP belonged. I was hoping others may also have experienced.

If you did that, where are the results? I don't see them in this thread.

Posting the results so others can see will help you get your answers. Just saying "They are different, and it stops at one point in the one" tells us nothing.

Stops where? What is the host name, IP, location, what Hop#? All of that is important in trying to figure this out.

And yes, getting a new IP does change routing and all that, as the IP comes from a different DHCP host or server in a different part of the country. Your routing would be different, and that all effects things in the end.

If it does turn out that a provider along the way is blocking a range of IP's, having the server name or IP could help in that research. We could then figure out who owns that server, contact them, and verify that they are blocking a range of IP's. But, when you say "traffic stops at a couple of hops before destination", that tells us nothing.

--Brian
--
============================
--Brian Plencner

E-Mail: CoasterBrian72Cancer@gmail.com
Note: Kill Cancer to Reply via e-mail


NetFixer
Snarl For The Camera Please
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
reply to neil0311

When you force an IP address change for your Comcast connection, two things may happen.

Your new IP address may be in a different subnet than it was before, and that can change the routing path in both directions.

Any particular IP address that Comcast assigns to your connection may actually be a "new" IP address in an IP address block that Comcast recently purchased. Some web servers (and/or web hosting services) do indeed block specific IP addresses and address ranges for a variety of reasons. The operators of those sites may not be aware that the ownership of the IP address block in question has changed, so they simply continue to block access from that IP address range.

Unless you can/will supply specific information, nobody can do anything but reply to your post with generic guesses.
--
We can never have enough of nature.
We need to witness our own limits transgressed, and some life pasturing freely where we never wander.


neil0311

join:2005-07-24
Marietta, GA
reply to neil0311

Thanks for the replies. I understand how a DHCP lease is given out and the variance of your IP and the corresponding subnet and the effect this has on potential routes.

Wasn't looking to dissect tracert's. Just wanted to know if others have had similar experiences and the causes in their case. Guess no one has....nuff said.



pflog
Bueller? Bueller?
Premium,MVM
join:2001-09-01
El Dorado Hills, CA
kudos:3

said by neil0311:

Thanks for the replies. I understand how a DHCP lease is given out and the variance of your IP and the corresponding subnet and the effect this has on potential routes.

Wasn't looking to dissect tracert's. Just wanted to know if others have had similar experiences and the causes in their case. Guess no one has....nuff said.

In that case, why not post a poll instead? It doesn't seem like you're interested in fixing it, and you have your workaround to fix it locally. If you're just interested in seeing if it's a widespread issue, a poll would be more suitable.
--
"I drank what?" -Socrates