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On Fri, Dec 5, 2008 at 10:05 AM, Evgeniy Bushkov <zhen@×××××××××.ru> wrote: |
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> Adam Carter пишет: |
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>>> |
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>>> Also take a note that there are no "known-compromised hosts" |
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>>> |
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>> |
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>> What about hosts listed in RBLs? |
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>> http://en.wikipedia.org/wiki/Comparison_of_DNS_blacklists. It would be |
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>> interesting to see if how much correlation there is between ssh brute |
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>> forcing bots and the contents of the various lists. |
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>> |
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> |
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> It's just interesting. But I don't trust them enough. I don't know how these |
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> lists were composed. We've periodically seen viruses outbreaks, some |
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> computers IPs could get into lists because of trojans and so on. One day you |
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> won't reach your server from your own home computer... |
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|
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The fact that a lot of 'compromised hosts' are home users with |
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providers like comcast, verizon, etc lends another trouble as well... |
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dynamic IPs mean that the next person with the luck of the draw in |
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getting that IP can't reach your servers either, and if *you* happen |
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to be that person, no reasonable whitelist will ever get you back in |
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from that location until you get another IP. |
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|
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>> |
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>> |
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>>> |
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>>> because ANY IP can be forged. |
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>>> |
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>> |
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>> Its easy enough to forge a SYN, but to setup a session so you can make a |
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>> password guessing attempt requires that you also get the packets back from |
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>> the server, which is an order of magnitude more difficult. Ever since OSes |
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>> have implemented well chosen initial sequence numbers, spoofing of TCP |
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>> sessions has become very difficult. |
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>> |
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>> |
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> |
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> I agree but as admin I prefer to think about many things worse than they |
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> really are. If something wrong is possible it's better to avoid it |
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> beforehand. |
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> |
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> Best regards, |
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> Evgeniy B. |
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|
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Careful with that line of thinking... you'll inevitably come to the |
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conclusion that there's no hope and you're better off just turning the |
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system off, unplugging it from the wall, and locking it into a very |
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sturdy vault deep beneath a very solid mountain! (until you ponder |
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yourself insane over the security risks that exist even then, let |
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alone the impact on usability) |
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|
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-- |
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Poison [BLX] |
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Joshua M. Murphy |
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