comes in on is the same interface that we would route out of to get to
the packet's source address. Essentially automates an anti-spoofing
check using the information in the routing table.
Experimental. The usage and rule format for the feature may still be
subject to change.
default-to-deny firewall. Simply turning off IPFW via a preexisting
sysctl does the job. To make it more apparent (since nobody picked up
on this in a week's worth of flames), the boolean sysctl's have been
integrated into the /sbin/ipfw command set in an obvious and straightforward
manner. For example, you can now do 'ipfw disable firewall' or
'ipfw enable firewall'. This is far easier to remember then the
net.inet.ip.fw.enable sysctl.
Reviewed by: imp
MFC after: 3 days
after -p except for the last (the ruleset file to process) to the
preprocessor for interpretation. This allows command-line options besides
-U and -D to be passed to cpp(1) and m4(1) as well as making it easier to
use other preprocessors.
Sponsored By: NTT Multimedia Communications Labs
MFC after: 1 week
to net.inet.ip.fw.one_pass.
Add to notes to explain the exact behaviour of "prob xxx" and "log"
options.
Virtually approved by: re (mentioned in rev.1.19 of ip_fw2.c)
following Julian's good suggestion: since you can specify any match
pattern as an option, rules now have the following format:
[<proto> from <src> to <dst>] [options]
i.e. the first part is now entirely optional (and left there just
for compatibility with ipfw1 rulesets).
Add a "-c" flag to show/list rules in the compact form
(i.e. without the "ip from any to any" part) when possible.
The default is to include it so that scripts processing ipfw's
canonical output will still work.
Note that as part of this cleanup (and to remove ambiguity), MAC
fields now can only be specified in the options part.
Update the manpage to reflect the syntax.
Clarify the behaviour when a match is attempted on fields which
are not present in the packet, e.g. port numbers on non TCP/UDP
packets, and the "not" operator is specified. E.g.
ipfw add allow not src-port 80
will match also ICMP packets because they do not have port numbers, so
"src-port 80" will fail and "not src-port 80" will succeed. For such
cases it is advised to insert further options to prevent undesired results
(e.g. in the case above, "ipfw add allow proto tcp not src-port 80").
We definitely need to rewrite the parser using lex and yacc!
render the syntax less ambiguous.
Now rules can be in one of these two forms
<action> <protocol> from <src> to <dst> [options]
<action> MAC dst-mac src-mac mac-type [options]
however you can now specify MAC and IP header fields as options e.g.
ipfw add allow all from any to any mac-type arp
ipfw add allow all from any to any { dst-ip me or src-ip me }
which makes complex expressions a lot easier to write and parse.
The "all from any to any" part is there just for backward compatibility.
Manpage updated accordingly.
Implement the M_SKIP_FIREWALL bit in m_flags to avoid loops
for firewall-generated packets (the constant has to go in sys/mbuf.h).
Better comments on keepalive generation, and enforce dyn_rst_lifetime
and dyn_fin_lifetime to be less than dyn_keepalive_period.
Enforce limits (up to 64k) on the number of dynamic buckets, and
retry allocation with smaller sizes.
Raise default number of dynamic rules to 4096.
Improved handling of set of rules -- now you can atomically
enable/disable multiple sets, move rules from one set to another,
and swap sets.
sbin/ipfw/ipfw2.c:
userland support for "noerror" pipe attribute.
userland support for sets of rules.
minor improvements on rule parsing and printing.
sbin/ipfw/ipfw.8:
more documentation on ipfw2 extensions, differences from ipfw1
(so we can use the same manpage for both), stateful rules,
and some additional examples.
Feedback and more examples needed here.
with ipfw2 extensions and give examples of use of the new features.
This is just a preliminary commit, where i simply added the basic
syntax for the extensions, and clean up the page (e.g. by listing
things in alphabetical rather than random order).
I would appreciate feedback and possible corrections/extensions
by interested parties.
Still missing are a more detailed description of stateful rules
(with keepalives), interaction with of stateful rules and natd (don't do
that!), examples of use with the recently introduced rule sets.
There is an issue related to the MFC: RELENG_4 still has ipfw as a
default, and ipfw2 is optional. We have two options here: MFC this
page as ipfw(8) adding a large number of "SORRY NOT IN IPFW" notes,
or create a new ipfw2(8) manpage just for -stable users. I am all
for the first approach, but of course am listening to your comments.
more on how ipfw(8) deals with tiny fragments. While we're at it, add
a quick log message to even let people know we dropped a packet. (Note
that the second FINE POINT is somewhat redundant given the first, but
since the code is there, leave the docs for it.)
MFC after: 1 day
reinserted by a userland process, will lose a number of packet
attributes, including their source interface. This may affect
the behavior of later rules, and while not strictly a BUG, may
cause unexpected behavior if not clearly documented. A similar
note for natd(8) might be desirable.
ipfirewall(4) to the IMPLEMENTATION NOTES section because it
considers kernel internals and may confuse newbies if placed
at the very beginning of the manpage (where it used to be previously.)
Not objected by: luigi
Fair Queueing) and RED (Random Early Detection) to both give the reader
a hint what they are and to make it easier to find out more information
about them.
addresses (and the macros that ipfw(4) use to lookup data for the 'me'
keyword have been converted) remove a comment about using 'me' being a
"computationally expensive" operation.
while I'm here, change two instances of "IP number" to "IP address"
+ implement "limit" rules, which permit to limit the number of sessions
between certain host pairs (according to masks). These are a special
type of stateful rules, which might be of interest in some cases.
See the ipfw manpage for details.
+ merge the list pointers and ipfw rule descriptors in the kernel, so
the code is smaller, faster and more readable. This patch basically
consists in replacing "foo->rule->bar" with "rule->bar" all over
the place.
I have been willing to do this for ages!
MFC after: 1 week
Avoid using parenthesis enclosure macros (.Pq and .Po/.Pc) with plain text.
Not only this slows down the mdoc(7) processing significantly, but it also
has an undesired (in this case) effect of disabling hyphenation within the
entire enclosed block.
but list them if -d was specified).
Avoid listing expired dynamic rules unless the (new) -e option was specified.
If specific rule numbers were listed on the command line, and the -d flag was
specified, only list dynamic rules that match the specified rule numbers.
Try to partly clean up the bleeding mess this file has become. If there is
any justice in this world, the responsible parties (you know who you are!)
should expect to wake up one morning with a horse's head in their bed. The
code still looks like spaghetti, but at least now it's *properly intented*
spaghetti (hmm? did somebody say "tagliatelle"?).
rules. Also, don't show dynamic rules if you only asked to see a
certain rule number.
PR: 18550
Submitted by: Lyndon Nerenberg <lyndon@orthanc.ab.ca>
Approved by: luigi
MFC after: 2 weeks
address is configured on a interface. This is useful for routers with
dynamic interfaces. It is now possible to say:
0100 allow tcp from any to any established
0200 skipto 1000 tcp from any to any
0300 allow ip from any to any
1000 allow tcp from 1.2.3.4 to me 22
1010 deny tcp from any to me 22
1020 allow tcp from any to any
and not have to worry about the behaviour if dynamic interfaces configure
new IP numbers later on.
The check is semi expensive (traverses the interface address list)
so it should be protected as in the above example if high performance
is a requirement.
