This is a harness to help with fuzzing KEX.
To use it, you first set it to count packets in each direction:
./kexfuzz -K diffie-hellman-group1-sha1 -k host_ed25519_key -c
S2C: 29
C2S: 31
Then get it to record a particular packet (in this case the 4th
packet from client->server):
./kexfuzz -K diffie-hellman-group1-sha1 -k host_ed25519_key \
-d -D C2S -i 3 -f packet_3
Fuzz the packet somehow:
dd if=/dev/urandom of=packet_3 bs=32 count=1 # Just for example
Then re-run the key exchange substituting the modified packet in
its original sequence:
./kexfuzz -K diffie-hellman-group1-sha1 -k host_ed25519_key \
-r -D C2S -i 3 -f packet_3
A comprehensive KEX fuzz run would fuzz every packet in both
directions for each key exchange type and every hostkey type.
This will take some time.
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