is not called, and no static rules match an outgoing packet, the
latter retains its source IP address. This is in support of the
"static NAT only" mode.
no punch_fw was used.
Fix another couple of bugs which prevented rules from being
installed properly.
On passing, use IPFW2 instead of NEW_IPFW to compile the new code,
and slightly simplify the instruction generation code.
This code makes use of variable-size kernel representation of rules
(exactly the same concept of BPF instructions, as used in the BSDI's
firewall), which makes firewall operation a lot faster, and the
code more readable and easier to extend and debug.
The interface with the rest of the system is unchanged, as witnessed
by this commit. The only extra kernel files that I am touching
are if_fw.h and ip_dummynet.c, which is quite tied to ipfw. In
userland I only had to touch those programs which manipulate the
internal representation of firewall rules).
The code is almost entirely new (and I believe I have written the
vast majority of those sections which were taken from the former
ip_fw.c), so rather than modifying the old ip_fw.c I decided to
create a new file, sys/netinet/ip_fw2.c . Same for the user
interface, which is in sbin/ipfw/ipfw2.c (it still compiles to
/sbin/ipfw). The old files are still there, and will be removed
in due time.
I have not renamed the header file because it would have required
touching a one-line change to a number of kernel files.
In terms of user interface, the new "ipfw" is supposed to accepts
the old syntax for ipfw rules (and produce the same output with
"ipfw show". Only a couple of the old options (out of some 30 of
them) has not been implemented, but they will be soon.
On the other hand, the new code has some very powerful extensions.
First, you can put "or" connectives between match fields (and soon
also between options), and write things like
ipfw add allow ip from { 1.2.3.4/27 or 5.6.7.8/30 } 10-23,25,1024-3000 to any
This should make rulesets slightly more compact (and lines longer!),
by condensing 2 or more of the old rules into single ones.
Also, as an example of how easy the rules can be extended, I have
implemented an 'address set' match pattern, where you can specify
an IP address in a format like this:
10.20.30.0/26{18,44,33,22,9}
which will match the set of hosts listed in braces belonging to the
subnet 10.20.30.0/26 . The match is done using a bitmap, so it is
essentially a constant time operation requiring a handful of CPU
instructions (and a very small amount of memmory -- for a full /24
subnet, the instruction only consumes 40 bytes).
Again, in this commit I have focused on functionality and tried
to minimize changes to the other parts of the system. Some performance
improvement can be achieved with minor changes to the interface of
ip_fw_chk_t. This will be done later when this code is settled.
The code is meant to compile unmodified on RELENG_4 (once the
PACKET_TAG_* changes have been merged), for this reason
you will see #ifdef __FreeBSD_version in a couple of places.
This should minimize errors when (hopefully soon) it will be time
to do the MFC.
for passive mode data connections (PASV/EPSV -> 227/229). Well,
the actual punching happens a bit later, when the aliasing link
becomes fully specified.
Prodded by: Danny Carroll <dannycarroll@hotmail.com>
MFC after: 1 week
NAT in extended passive mode if the server's public IP address was
different from the main NAT address. This caused a wrong aliasing
link to be created that did not route the incoming packets back to
the original IP address of the server.
natd -v -n pub0 -redirect_address localFTP publicFTP
Note that even if localFTP == publicFTP, one still needs to supply
the -redirect_address directive. It is needed as a helper because
extended passive mode's 229 reply does not contain the IP address.
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.
For FTP control connection, keep the CRLF end-of-line termination
status in there.
Fixed the bug when the first FTP command in a session was ignored.
PR: 24048
MFC after: 1 week
PPTP links are no longer dropped by simple (and inappropriate in this
case) "inactivity timeout" procedure, only when requested through the
control connection.
It is now possible to have multiple PPTP servers running behind NAT.
Just redirect the incoming TCP traffic to port 1723, everything else
is done transparently.
Problems were reported and the fix was tested by:
Michael Adler <Michael.Adler@compaq.com>,
David Andersen <dga@lcs.mit.edu>
datagram embedded into ICMP error message, not with protocol
field of ICMP message itself (which is always IPPROTO_ICMP).
Pointed by: Erik Salander <erik@whistle.com>
not alias `ip_src' unless it comes from the host an original
datagram that triggered this error message was destined for.
PR: 20712
Reviewed by: brian, Charles Mott <cmott@scientech.com>
- Multiple PPTP clients behind NAT to the same or different servers.
- Single PPTP server behind NAT -- you just need to redirect TCP
port 1723 to a local machine. Multiple servers behind NAT is
possible but would require a simple API change.
- No API changes!
For more information on how this works see comments at the start of
the alias_pptp.c.
PacketAliasPptp() is no longer necessary and will be removed soon.
Submitted by: Erik Salander <erik@whistle.com>
Reviewed by: ru
Rewritten by: ru
Reviewed by: Erik Salander <erik@whistle.com>
It does mean that it is now possible to run passive-mode FTP
server behind NAT.
- SECURITY: FTP aliasing engine now ensures that:
o the segment preceding a PORT/227 segment terminates with a \r\n;
o the IP address in the PORT/227 matches the source IP address of
the packet;
o the port number in the PORT command or 277 reply is greater than
or equal to 1024.
Submitted by: Erik Salander <erik@whistle.com>
Reviewed by: ru
to PPTP) with more generic PacketAliasRedirectProto().
Major number is not bumped because it is believed that noone
has started using PacketAliasRedirectPptp() yet.
LSNAT links are first created by either PacketAliasRedirectPort() or
PacketAliasRedirectAddress() and then set up by one or more calls to
PacketAliasAddServer().
connections, after SYN packets were seen from both ends. Before this,
it would get applied right after the first SYN packet was seen (either
from client or server). With broken TCP connection attempts, when the
remote end does not respond with SYNACK nor with RST, this resulted in
having a useless (ie, no actual TCP connection associated with it) TCP
link with 86400 seconds TTL, wasting system memory. With high rate of
such broken connection attempts (for example, remote end simply blocks
these connection attempts with ipfw(8) without sending RST back), this
could result in a denial-of-service.
PR: bin/17963
but with `dst_port' work for outgoing packets.
This case was not handled properly when I first fixed this
in revision 1.17.
This change is also required for the upcoming improved PPTP
support patches -- that is how I found the problem.
Before this change:
# natd -v -a aliasIP \
-redirect_port tcp localIP:localPORT publicIP:publicPORT 0:remotePORT
Out [TCP] [TCP] localIP:localPORT -> remoteIP:remotePORT aliased to
[TCP] aliasIP:localPORT -> remoteIP:remotePORT
After this change:
# natd -v -a aliasIP \
-redirect_port tcp localIP:localPORT publicIP:publicPORT 0:remotePORT
Out [TCP] [TCP] localIP:localPORT -> remoteIP:remotePORT aliased to
[TCP] publicIP:publicPORT -> remoteIP:remotePORT
INADDR_NONE: Incoming packets go to the alias address (the default)
INADDR_ANY: Incoming packets are not NAT'd (direct access to the
internal network from outside)
anything else: Incoming packets go to the specified address
Change a few inaddr::s_addr == 0 to inaddr::s_addr == INADDR_ANY
while I'm there.
redirected and when no target address has been specified, NAT
the destination address to the alias address rather than
allowing people direct access to your internal network from
outside.
the link are equal to the default aliasing address. Do not zero them!
This will fix the problem with non-working links added with the source
and/or aliasing address equal to the default aliasing address, but the
default aliasing address is set later, after the link has been set up,
like both natd(8) and ppp(8) do (for objective reasons).
Reviewed by: Brian Somers <brian@FreeBSD.org>,
Eivind Eklund <eivind@FreeBSD.org>,
Charles Mott <cmott@srv.net>
`dst_port') work for outgoing packets.
- Make permanent links whose `alias_addr' matches the primary aliasing
address `aliasAddress' work for incoming packets.
- Typo fixes.
Reviewed by: brian, eivind
In the words of originator:
:If an incoming connection is initiated through natd and deny_incoming is
:not set, then a new alias_link structure is created to handle the link.
:If there is nothing listening for the incoming connection, then the kernel
:responds with a RST for the connection. However, this is not processed
:correctly in libalias/alias.c:TcpMonitor{In,Out} and
:libalias/alias_db.c:SetState{In,Out} as it thinks a connection
:has been established and therefore applies a timeout of 86400 seconds
:to the link.
:
:If many of these half-connections are initiated (during, for example, a
:port scan of the host), then many thousands of unnecessary links are
:created and the resident size of natd balloons to 20MB or more.
PR: 13639
Reviewed by: brian
- Sort xrefs
- FreeBSD.ORG -> FreeBSD.org
- Be consistent with section names as outlines in mdoc(7)
- Other misc mdoc cleanup.
PR: doc/13144
Submitted by: Alexy M. Zelkin <phantom@cris.net>
