new Bro pre-release available - 0.7a61

[Vern Paxson]

A new Bro pre-release is now available from:

	ftp://ftp.ee.lbl.gov/.vp-bro-pub-0.7a61.tar.gz

The most timely change is the addition of an NTP analyzer that can detect
the new NTP remote root compromise attack.

A summary of the changes with respect to 0.7a48:

	- An NTP analyzer has been added.  See policy/ntp.bro for a
	  corresponding policy file that detects the newly discovered
	  NTP remote buffer overflow attack.

	- example-attacks/ is a new directory that contains trace files
	  of attacks.  Currently, there are just two to play with:

		bro -r example-attacks/ftp-site-exec.trace mt

	  will run on a trace of a "site exec" overflow attack, and

		bro -r example-attacks/ntp-attack.trace mt ntp

	  will run on an example of the NTP overflow.

	- The doc/ directory includes the postscript and HTML versions
	  of the first draft of the Bro manual.

	- A new policy file, icmp.bro, has preliminary (and only
	  partially developed) policy for analyzing ICMP.

	- The file libpcap.bufsize.patch includes the patch necessary
	  on some systems to increase the maximum libpcap buffer size.

	- You can now use anonymous functions in &default expressions,
	  so for example you can do:

		global foo: table[count] of string = {
			[1] = "1st", [2] = "2nd", [3] = "3rd",
		} &default = function(n: count): string { return fmt("%dth", n); };

	  and then referring to foo[5] will yield "5th".

	- There's now a "for" statement to iterate over the indices of
	  a table or the members of a set:

		for ( i in foo )

	  for the above "foo" will iterate with i assigned to 1, 2, and 3;
	  *but not in general in that order*.

	- The function contains_string() has been removed, and now you
	  can instead use an expression like

		"bar" in "foobar"

	  which will yield T.
  
	- The scan detection now has a mechanism for attempting to detect
	  SYN flooding backscatter and flagging it as different from a
	  stealth scan.

	- New event handlers:
		
		new_connection_contents()
			like new_connection(), but reassembles the
			stream so you can use set_content_files() to
			write it to a file

		udp_session_done()
			invoked when a UDP session (which is defined on
			a per-protocol basis; currently only for NTP)
			finishes.

		ntp_message()
			invoked for each NTP message

	- UDP processing now does accounting for detecting scans.

	- UDP processing now tracks numbers of requests/replies for
	  sessions that support that notion.  The connections are
	  annotated by udp_session_done() with "[m,n]" for "m"
	  requests and "n" replies, providing either m or n > 1.

	- New variable accessible from policy:

		watchdog_interval
			how often the watchdog should check for whether
			Bro is making internal progress
  
	- A bunch of functions no longer have a first argument of the
	  current time; get it instead from network_time() if you need it:

		authentication_accepted
		authentication_rejected
		conn_weird
		conn_weird_addl
		flow_weird
		net_weird
  
	- A bunch of functions now return bool rather than int values:

		set_contents_file
		set_login_state
		set_record_packets
		skip_further_processing

	- The variable "hot_dests" has been renamed to "hot_dsts".
  
	- 111/tcp is now identified as "portmap" rather than "rpc".

	- Connections flagged as hot for some types of characteristics
	  are now annotated with the reason associated with the
	  decision.  (I think a lot more of this is needed.)

	- Portmapper dumps are annotated with the results of the mapping.
	  This will be streamlined in the future.

- Vern