liblua and libm. This is necessary for static builds of Nmap, such as RPM
builds. Before this the error that was caused looked like
SCRIPT ENGINE: error while initializing script rules:
error loading module 'bit' from file '/usr/libexec/nmap/nselib-bin/bit.so':
/usr/libexec/nmap/nselib-bin/bit.so: undefined symbol: lua_pushnumber
stack traceback:
[C]: ?
[C]: in function 'require'
/usr/share/nmap/nselib/packet.lua:12: in main chunk
[C]: in function 'require'
/usr/share/nmap/scripts/rpcinfo.nse:10: in main chunk
[C]: ?
[C]: in function 'Entry'
/usr/share/nmap/scripts/script.db:8: in main chunk
[C]: ?
[C]: ?
probes, especially IP protocol probes.
Previously if IP protocol ping (-PO) was used anywhere in a host
discovery scan, any response was treated as a protocol response. (The
handlers for other response types had an explicit check for this.) This
means that if you did
nmap -PS -PO
and got back a SYN/ACK in response to the -PS probe, it would be marked
with a reason of proto-response rather than syn-ack. Now, because the IP
protocol response handler matches so broadly, it is given the last
chance at handling a response, only if no interpretation makes sense.
Now the aforementioned scan will give a reason of syn-ack.
The old behavior was not only misleading with respect to reasons, it had
a minor and subtle bug. Consider the following packet trace:
SENT (2.0990s) TCP 192.168.0.21:42205 > target:25 S ttl=40 id=39342 iplen=44 seq=114128202 win=1024 <mss 1460>
SENT (2.2560s) TCP 192.168.0.21:42205 > target:53 S ttl=40 id=51247 iplen=44 seq=114128202 win=1024 <mss 1460>
SENT (2.3280s) TCP 192.168.0.21:42206 > target:25 S ttl=37 id=31111 iplen=44 seq=114062667 win=2048 <mss 1460>
RCVD (2.3530s) TCP target:53 > 192.168.0.21:42205 SA ttl=51 id=0 iplen=44 seq=4159224453 win=5840 ack=114128203 <mss 1460>
ultrascan_host_probe_update called for machine target state UNKNOWN -> HOST_UP (trynum 1 time: 25123)
Ultrascan DROPPED probe packet to target detected
Changing ping technique for target to tcp to port 25; flags: S
Why is the received packet marked as a drop? And why is the ping
technique change to SYN to port 25 when the response came back from port
53? The reason is that the IP protocol response handler caught the probe
and decided it was in response to one of the sent TCP probes--any of the
TCP probes. It selected the probe to port 25 essentially at random and
used that as the relevant probe. The result is that a drop is wrongly
recorded (slowing down the scan), and a worse than useless ping probe is
used (worse than useless because it will cause another drop any time
it's used).
I found this while trying to emulate PortBunny's default ping scan,
which is
-PS80,25,22,443,21,113,23,53,554,3389,445 -PA3333,11 -PE -PP -PU161,162 -PO51
though not in the same order Nmap uses.
periods itself rather than relying on NSE's old behavior of replacing non-
printable characters with periods. Thanks to Rob Nicholls for reporting the
problem. [Kris]
