BootAble – FreeDOS boot testing freeware
To obtain direct, low-level access to a system's mass storage drives, SpinRite runs under a GRC-customized version of FreeDOS which has been modified to add compatibility with all file systems. In order to run SpinRite it must first be possible to boot FreeDOS.
GRC's “BootAble” freeware allows anyone to easily create BIOS-bootable media in order to workout and confirm the details of getting a machine to boot FreeDOS through a BIOS. Once the means of doing that has been determined, the media created by SpinRite can be booted and run in the same way.
The participants here, who have taken the time to share their knowledge and experience, their successes and some frustrations with booting their computers into FreeDOS, have created a valuable knowledgebase which will benefit everyone who follows.
You may click on the image to the right to obtain your own copy of BootAble. Then use the knowledge and experience documented here to boot your computer(s) into FreeDOS. And please do not hesitate to ask questions – nowhere else can better answers be found.
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www.grc.com
it will get resolved to GRC's web server IP address.This is interesting!The source port is a crucial thing from a security perspective. It's meant to be random, but within a certain range. When your PC initiates a connection to the external service, it will be given a source port by the OS as part of the protocol/API. It might be a number like 31084. This is used by your router when it maps the connection on the way out and on the way back in. This is how multiple connections to the same service (or web page) can be differentiated. When the connection closes, the port number is "forgotten" and won't be reused for quite some time. This makes it difficult for an attacker to work their way through your NAT to the PCs on the inside without having been first contacted by you.
In theory, I suppose, yes. In practice however, in TCP, its the tuple of the 4 values that is unique, and they would probably need to have all four to find a way to interfere with your systems. This means they need to know what source port and target port are in use on a connection between which two IP addresses. This presumes, at the minimum, that they're specifically focusing on one target, and not initiating a general attack. They could easily know these things by playing a man in the middle, for example. On the other hand, this is the reason why these days we layer TLS on top of TCP, to protect our data and messages from interference from an attacker.a determined enough attacker could keep trying different port numbers in the range until they hit on the right one?
I don't understand this scenario if by "connected to a modem" you imply connected to the internet, and in option 2, you are only connected to the router, but NOT to the internet, you would not be able to get ShieldsUp to run.Simplistically, what is the difference if I invoke ShieldsUP! from my computer,
1) when it is connected to the network router which is connected to a modem
AND
2) when the computer is directly connected to the router.
computer:port
to explain everything.servera:80
, and we'll say there's also a serverb that could be a port scanner (like what Shields Up does)client:35246 <---> servera:80
. While the connection is opened, if serverb attempts to connect (with its own random port for the source), if it attempts to connect to client:35246
, the OS on the client will treat it as if serverb were trying to connect to any other port that would be unused, either just ignoring it, or tell serverb that the port is closed.servera:80
and it will just pick a random port of its own, and when servera returns data, the router will receive it, look at its table, and return it to your computer.client:35246 <---> servera:80
, but servera will see this router:34851 <---> servera:80
. The final chain would look something like this as a result: client:35246 <--- router:34851 ---> servera:80
If you are running Linux, you may have configured the internet signin in your networking software. As I said, it depends on your ISP, some validate sessions using things like the modem/router MAC address, some require a username and password.Hi AlanD, interesting.
In the past, for testing purposes, I believe I have connected my computer directly to my ISP modem and was able to surf without running special software. But, I haven’t tried recently, and it would have to be software running on Linux, not Windows.