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Diffstat (limited to 'netsec-assignment3-S4498062/exercise1')
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diff --git a/netsec-assignment3-S4498062/exercise1 b/netsec-assignment3-S4498062/exercise1 new file mode 100644 index 0000000..62316b3 --- /dev/null +++ b/netsec-assignment3-S4498062/exercise1 @@ -0,0 +1,23 @@ +a: You send an IP packet with someone else's IP as source IP. For example, if some server holds a list with administrator IPs (that being the only protection), you could IP-spoof an administrator (assuming you know their IP) and do some stuff. However, in the most basic form you don't get the reply, because it's directed at the spoofed IP address. + + You don't need to do anything special. Just send the packet. That does mean you need access to a somewhat lower level (you would need root rights). It would also be good to know the IP of the machine you want to pretend to be. + +b: Both protocols have a checksum in the header that won't be valid any more after modifying the source IP address + +c: The handshake: + + Mallory Alice Bob + SYN-SENT ---> LISTEN # the SYN, supposed to flood Alice + SYN-RECEIVED ---> ESTABLISHED # Alice SYN-ACKs the SYN to Bob + ESTABLISHED <--- ESTABLISHED # Bob could, depending on the implementation, ACK the SYN-ACK, establishing a connection + + If the latter happens, the connection doesn't remain in the SYN queue, and as a result the SYN queue will never flood. + +d: Mallory Alice Gateway + SYN-SENT ---> LISTEN + SYN-RECEIVED --find Ursula--> FIND-URSULA + LISTEN <--unreachable-- NOT-FOUND + + Alice will make an attempt to reach Ursula through a gateway using ICMP. The gateway however cannot find Ursula, and will respond with a `Destination Unreachable' ICMP message. Alice will then no longer expect to get her SYN-ACK to Ursula ACKed, so she will remove the connection from the SYN queue. Again, the SYN queue will never flood. + +e: |