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On Wed, Dec 3, 2008 at 2:02 PM, Steve <Gentoo_sjh@×××××××.uk> wrote: |
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> I've recently discovered a curious pattern emerging in my system log |
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> with failed login attempts via ssh. |
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> |
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> Previously, I noticed dictionary attacks launched - which were easy to |
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> detect... and I've a process to block the IP address of any host that |
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> repeatedly fails to authenticate. |
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> |
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> What I see now is quite different... I'm seeing a dictionary attack |
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> originating from a wide range of IP addresses - testing user-names in |
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> sequence... it has been in progress since 22nd November 2008 and has |
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> tried 7195 user names in alphabetical order from 521 distinct hosts - |
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> with no successive two attempts from the same host. |
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This has been going on all year, you're lucky if you just started |
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getting it. :) |
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AFAIK nobody has found any specific fingerprint or anything to block |
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it by. The "solution" seems to be: only allow SSH from specific IP |
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addresses, don't use port 22, don't use password auth, use some kind |
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of portknocking, etc. as you already alluded to. If you Google for |
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distributed ssh brute force attacks, there are some fairly detailed |
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articles out there from earlier in the year. |
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Good luck :) |
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Paul |
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