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My localhost's IP address/port is being blocked from accessing a certain site. The blocking is occurring, but I don't know where.

The question is : does IP blocking possibly occur not only at the endpoint, but also at any intermediate server along the way?

Take a tracert, for example. Could the IP blocking be possibly occuring at any server whatsoever along the tracert path, or can the blocking only be done at the endpoints?

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The Peoples Republic of China has invested a tremendous amount in this area -… – emory Apr 14 '12 at 18:15
up vote 3 down vote accepted

Yes it can, intermediary devices such as firewalls and routers can have ACL's in place to stop certain IP's from passing through them.

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It can be blocked anywhere it passes through, and routers can have routing issues anywhere it passes through.

A reasonable conclusion is either that the site is blocking you (possibly for automated reasons) or, more likely, that some router between you and them thinks your IP (or that of the other endpoint) is somewhere it isn't.

Also... if you are accessing the site, generally the source port you use to do so is random, and the destination port is associated with the protocol (not you, so you don't have an IP address and port, but just an IP address).

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