need to have all the routes available before assigning interfaces to handle a
situation like the following:
# nmap --iflist
************************INTERFACES************************
DEV (SHORT) IP/MASK TYPE UP MAC
lo0 (lo0) 127.0.0.1/8 loopback up
ppp0 (ppp0) YY.YY.YY.YY/16 point2point up
# netstat -rn
Destination Gateway Flags Refs Use Netif Expire
default XX.XX.XX.XX UGSc 7 16 ppp0
XX.XX.XX.XX YY.YY.YY.YY UH 8 0 ppp0
Here the second route can be matched up immediately with the ppp0 device,
because the YY.YY.YY.YY gateway address matches the YY.YY.YY.YY/16 IP and mask
of ppp0. But the first route (default) needs to go through the second route in
order to find its interface. So we don't reject the default route immediately,
but save it an try to match it with an interface after all routes have been
found. See http://seclists.org/nmap-dev/2008/q4/0576.html for more information.
positive response that results in being marked filtered, the reply was an ICMP
error. Such probes are now ranked a 2 along with UDP, IP proto, and other
probes that get ICMP replies that are likely to be rate limited. Previously
they got the highest rank, 6, because they were TCP probes other than SYN to an
open port. SYN to an open port retains its rank of 3.
socket). It's possible to get an EHOSTUNREACH or EHOSTDOWN (and possibly other
errors) against a nonexistent LAN host and formerly the socket wasn't closed.
This allowed Nmap's internal count of sockets to be less that the true count of
open sockets. It would eventually try to open too many sockets and quit with
the message
Socket creation in sendConnectScanProbe: Too many open files (24)
Be aware that in this message 24 is the errno, not the number of open files.
The script's filename cannot be acessed when a thread's target times out
because we do not have access to the thread's environment when it is yielded.
All we can do is print out which target timed out. This output can
unfortunately be printed out many times for each thread (it is currently
difficult to track).
i.e., the probe didn't just time out. This was the case before r11253 when I
mistakenly removed it. I meant only to allow ultrascan_adjust_timing to be
called when rcvdtime == NULL, but as a side effect I also allowed
max_successful_tryno to increase in that case too. I was able to get that bit
of code to run with rcvdtime == NULL in a normal scan, but I don't think it
happens often.
I also improved the comments in that block of code.
o A problem that caused OS detection to fail for most hosts in a
certain was fixed. It happened when sending raw Ethernet frames
(by default on Windows or on other platforms with --send-eth) to
hosts on a switched LAN. The destination MAC address was wrong for
most targets. The symptom was that only one out of each scan group
of 20 or 30 hosts would have a meaningful OS fingerprint. Thanks go
to Michael Head for running tests and especially Trent Snyder for
testing and finding the cause of the problem. [David]
This fixes the following bug: When scanning with an Ethernet handle (as
opposed to raw sockets), only the first host in an OS scan group would
get a result. All others would be blank fingerprints with R=N for every
probe. This was first noticed on Windows because Ethernet is the default
sending method, but it affects other platforms with --send-eth.
OS scan initialized an Ethernet handle once for each group, and recorded
the first-hop MAC address of the first target at that time. That
first-hop address was used for all targets. This failed on a switched
LAN, when the first-hop address for every host is different (it's the
MAC address of each target).
All the various high-level probe sending functions now do their work
through three low-level sending functions: one each for TCP, UDP, and
ICMP. Those low-level functions take care of setting the MAC addresses
before each send.
I checked and the other places where Ethernet sends are used do not have
this problem. ultra_scan, idle scan, and traceroute all set the
addresses before every send.
measurements. These commonly responsive ports are moved to the front of the
list when randomizing ports to help us quickly get some timing feedback and
find a timing ping probe.
The previous list was
{ 21, 22, 23, 25, 53, 80, 113, 256, 389, 443, 554, 636, 1723, 3389 }
The new list is
{ 80, 23, 443, 21, 22, 25, 3389, 110, 445, 139, 143, 53, 135, 113 }
The ports that were removed are
256 fw1-secureremote
389 ldap
554 rtsp
636 ldapssl
1723 pptp
The ports that were added are
110 pop3
135 msrpc
139 netbios-ssn
143 imap
445 microsoft-ds
Like ultra_scan, OS scan has global and host-based congestion control
mechanisms like those in TCP. Part of global congestion control is
keeping track of how many probes are outstanding in the network; OS scan
keeps the number in a member variable called num_probes_active.
num_probes_active is meant to be the sum of the sizes of each host's
list of outstanding probes. It was correctly being decremented whenever
a probe was removed from an active list, but it was never incremented.
num_probes_active was always zero or negative, and therefore never
exceeded the global congestion window. This almost completely disabled
global congestion control.
With this fix OS scan will send a maximum of ten probes immediately at
the beginning of the scan. Previously it was limited only by the number
of hosts being scanned (20 or 30).
