with the kernel compile time option:
options IPFIREWALL_FORWARD_EXTENDED
This option has to be specified in addition to IPFIRWALL_FORWARD.
With this option even packets targeted for an IP address local
to the host can be redirected. All restrictions to ensure proper
behaviour for locally generated packets are turned off. Firewall
rules have to be carefully crafted to make sure that things like
PMTU discovery do not break.
Document the two kernel options.
PR: kern/71910
PR: kern/73129
MFC after: 1 week
This commit replaces those with two new functions that simplify the code
and produce warnings that the syntax is deprecated. A small number of
sensible abbreviations may be explicitly added based on user feedback.
There were previously three types of strncmp use in ipfw:
- Most commonly, strncmp(av, "string", sizeof(av)) was used to allow av
to match string or any shortened form of it. I have replaced this
with a new function _substrcmp(av, "string") which returns 0 if av
is a substring of "string", but emits a warning if av is not exactly
"string".
- The next type was two instances of strncmp(av, "by", 2) which allowed
the abbreviation of bytes to "by", "byt", etc. Unfortunately, it
also supported "bykHUygh&*g&*7*ui". I added a second new function
_substrcmp2(av, "by", "bytes") which acts like the strncmp did, but
complains if the user doesn't spell out the word "bytes".
- There is also one correct use of strncmp to match "table(" which might
have another token after it without a space.
Since I changed all the lines anyway, I also fixed the treatment of
strncmp's return as a boolean in many cases. I also modified a few
strcmp cases as well to be fully consistent.
reversals+system lock ups if they are using ucred based rules
while running with debug.mpsafenet=1.
I am working on merging a shared locking mechanism into ipfw which
should take care of this problem, but it still requires a bit more
testing and review.
and sent to the DIVERT socket while the original packet continues with the
next rule. Unlike a normally diverted packet no IP reassembly attemts are
made on tee'd packets and they are passed upwards totally unmodified.
Note: This will not be MFC'd to 4.x because of major infrastucture changes.
PR: kern/64240 (and many others collapsed into that one)
contain O_UID, O_GID and O_JAIL opcodes, the F_NOT or F_OR logical
operator bits get clobbered. Making it impossible to use the ``NOT'' or
``OR'' operators with uid, gid and jail based constraints.
The ipfw_insn instruction template contains a ``len'' element which
stores two pieces of information, the size of the instruction
(in 32-bit words) in the low 6 bits of "len" with the 2 remaining
bits to implement OR and NOT.
The current code clobbers the OR and NOT bits by initializing the
``len'' element to the size, rather than OR'ing the bits. This change
fixes this by changing the initialization of cmd->len to an OR operation
for the O_UID, O_GID and O_JAIL opcodes.
This may be a MFC candidate for RELENG_5.
Reviewed by: andre
Approved by: luigi
PR: kern/63961 (partially)
keyword but without 'logamount' limit the amount of their log messages
by net.inet.ip.fw.verbose_limit sysctl value.
RELENG_5 candidate.
PR: kern/46080
Submitted by: Dan Pelleg
MFC after: 1 week
Since the only thing truly unique about a prison is it's ID, I figured
this would be the most granular way of handling this.
This commit makes the following changes:
- Adds tokenizing and parsing for the ``jail'' command line option
to the ipfw(8) userspace utility.
- Append the ipfw opcode list with O_JAIL.
- While Iam here, add a comment informing others that if they
want to add additional opcodes, they should append them to the end
of the list to avoid ABI breakage.
- Add ``fw_prid'' to the ipfw ucred cache structure.
- When initializing ucred cache, if the process is jailed,
set fw_prid to the prison ID, otherwise set it to -1.
- Update man page to reflect these changes.
This change was a strong motivator behind the ucred caching
mechanism in ipfw.
A sample usage of this new functionality could be:
ipfw add count ip from any to any jail 2
It should be noted that because ucred based constraints
are only implemented for TCP and UDP packets, the same
applies for jail associations.
Conceptual head nod by: pjd
Reviewed by: rwatson
Approved by: bmilekic (mentor)
For incoming packets, the packet's source address is checked if it
belongs to a directly connected network. If the network is directly
connected, then the interface the packet came on in is compared to
the interface the network is connected to. When incoming interface
and directly connected interface are not the same, the packet does
not match.
Usage example:
ipfw add deny ip from any to any not antispoof in
Manpage education by: ru
RTF_BLACKHOLE as well.
To quote the submitter:
The uRPF loose-check implementation by the industry vendors, at least on Cisco
and possibly Juniper, will fail the check if the route of the source address
is pointed to Null0 (on Juniper, discard or reject route). What this means is,
even if uRPF Loose-check finds the route, if the route is pointed to blackhole,
uRPF loose-check must fail. This allows people to utilize uRPF loose-check mode
as a pseudo-packet-firewall without using any manual filtering configuration --
one can simply inject a IGP or BGP prefix with next-hop set to a static route
that directs to null/discard facility. This results in uRPF Loose-check failing
on all packets with source addresses that are within the range of the nullroute.
Submitted by: James Jun <james@towardex.com>
o Add sanity checking to the firewall delete operation
which tells the user that a firewall rule
specification is required.
The previous behaviour was to exit without reporting any
errors to the user.
Approved by: bmilekic (mentor)
mac ipfw rules. The exact same sanity check is performed as
the first operation of add_mac(), so there is no sense
in doing it twice.
Approved by: bmilekic (mentor)
PR: bin/55981
source address of a packet exists in the routing table. The
default route is ignored because it would match everything and
render the check pointless.
This option is very useful for routers with a complete view of
the Internet (BGP) in the routing table to reject packets with
spoofed or unrouteable source addresses.
Example:
ipfw add 1000 deny ip from any to any not versrcreach
also known in Cisco-speak as:
ip verify unicast source reachable-via any
Reviewed by: luigi
