basic ccie security queries

HI experts

i have the following questions on URPF,

1) " ip verify unicast reverse path" and "ip verfiy souce rechable via rx "
are these commands have same effect or are they different .

2) secondly i dont see any use of " ip verfiy unicast source rechable via
any " command as it still allows packets to enter form one interface even
though their source address can be reached by other interface . This can
always open doors for spoof attacks . in what way this command is changing
security posture of a device ?

3) by default what is the encryption method used by snmp v3 if not specifed
. can i run both ver 2 and v3 simultanously on same device.

4) AS ssh allows for more advanced security by encrypting the session .
what encryption method it uses ?

5) what s default ASA firewall behavior when it receive fragmented packets .
(drop or farward ) . is their any similar concept in firewal like ios
Virtual fragment reassembly ?

6) what is defference if i add port security to the following command " ip
verify source " how does the processing behaves differently with "port
security " keyword

or i need to enable port security prior to issuing " ip vefigy source port
security "

Thanks

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Received on Mon Mar 07 2011 - 18:21:24 ART