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.
