Always, on every assignment, please write your name legibly as it appears
on your University ID and on the class list! All assignments will be due
at the start of class on the day indicated, and unless there is what
insurance companies call "an act of God" - something outside your
control; the only exceptions to this rule will be by advance arrangement.
For those taking the course by video link, assignments may be submitted
electronically by E-mail to
Rajiv Raman.
Please do not use obscure attachment formats! Plaintext E-mail is
preferred to HTML, Word, RTF or other even more obscure formats!
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Consider the ISO-OSI protocol hierarchy. If one connects two networks
through a gateway that serves as an address mapping mechanism, assigning
"virtual network addresses" to all machines seen through this gateway,
what possible security consequences are there?
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When you establish a ssh connection to a remote machine, you and the remote
machine must exchange keys somehow. Commonly, when you make your first
contact with a remote machine, ssh says "unknown host, add key to public key
database?" What vulnerabilities are there in the activity this implies?
Would they be any more vulnerable if symmetric key cryptography were used?
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When you connecto to a "secure web site", your web browser opens a little
dialog box saying that a secure connection has been established, and when you
move on to another site, another dialog box tells you that you are leaving the
security of that web page. For the sake of example, assume that the web
site is an E-commerce site.
List two very different classes of attacks that this web site is probably
unable to protect you from.
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In a directory structure, a "blind path" is a path name of a readable file
where where some directories on that path are not readable. For example,
on the departmental file server,
~/jones/.public-html/security/hw/07.html
is a blind path. You can open and read the file at the end of that path, but
you cannot read most of the directories along the path.
a) What security benefit is there to creating blind paths?
b) How can the equivalent of a blind path be created in the context of an
internet. Hint: Firewalls are involved.