Gain root access on linux servers with physical access

All -

I was wondering ideas on how to gain control of linux boxes with physical 
access to them in the hosting facility. 

The owner has code on them yet never bothered monitoring or gaining root access 
and her developers are blackmailing her. She has access the the hosting 
facility and the servers and backup staff yet needs to regain control of the 
servers.

I asked what OS are they? She did not know. nmap cannot tell and p0f states:
# p0f
p0f - passive os fingerprinting utility, version 2.0.8
(C) M. Zalewski <lcamtuf@dione.cc>, W. Stearns <wstearns@pobox.com>
p0f: listening (SYN) on 'eth0', 262 sigs (14 generic, cksum 0F1F5CA2), rule: 
'all'.
x.x.122.x:54368 - Linux 2.6 (newer, 2) (up: 410 hrs)
  -> x.114.33.x:80 (distance 0, link: ethernet/modem)

Any ideas how to get root with physical access? I remember in the past booting 
to a knoppix CD and messing with boot loader yet it has been a while.

Also the only ports open are 80 & 443.

Any ideas?



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