IPQ_SET_MODE(3) Linux Programmer's Manual IPQ_SET_MODE(3)NAME
ipq_set_mode -- set the ip_queue queuing mode
SYNOPSIS
#include <linux/netfilter.h>
#include <libipq.h>
int ipq_set_mode(const struct ipq_handle *h, u_int8_t mode, size_t range);
DESCRIPTION
The ipq_set_mode function sends a message to the kernel ip_queue module, specifying whether packet metadata only, or packet payloads as
well as metadata should be copied to userspace.
The h parameter is a context handle which must previously have been returned successfully from a call to ipq_create_handle.
The mode parameter must be one of:
IPQ_COPY_META
Copy only packet metadata to userspace.
IPQ_COPY_PACKET
Copy packet metadata and packet payloads to userspace.
The range parameter is used to specify how many bytes of the payload to copy to userspace. It is only valid for IPQ_COPY_PACKET mode and
is otherwise ignored. The maximum useful value for range is 65535 (greater values will be clamped to this by ip_queue).
ipq_set_mode is usually used immediately following ipq_create_handle to enable the flow of packets to userspace.
Note that as the underlying Netlink messaging transport is connectionless, the ip_queue module does not know that a userspace application
is ready to communicate until it receives a message such as this.
RETURN VALUE
On failure, -1 is returned.
On success, a non-zero positive value is returned.
ERRORS
On failure, a descriptive error message will be available via the ipq_errstr function.
DIAGNOSTICS
A relatively common failure may occur if the ip_queue module is not loaded. In this case, the following code excerpt:
status = ipq_set_mode(h, IPQ_COPY_META, 0);
if (status < 0) {
ipq_perror("myapp");
ipq_destroy_handle(h);
exit(1);
}
would generate the following output:
myapp: Failed to send netlink message: Connection refused
BUGS
None known.
AUTHOR
James Morris <jmorris@intercode.com.au>
COPYRIGHT
Copyright (c) 2000-2001 Netfilter Core Team.
Distributed under the GNU General Public License.
SEE ALSO libipq(3), iptables(8).
Linux iptables 1.2 16 October 2001 IPQ_SET_MODE(3)
Check Out this Related Man Page
IPQueue(3pm) User Contributed Perl Documentation IPQueue(3pm)NAME
IPTables::IPv4::IPQueue - Perl extension for libipq.
SYNOPSIS
use IPTables::IPv4::IPQueue qw(:constants);
$queue = new IPTables::IPv4::IPQueue();
$msg = $queue->get_message();
$queue->set_verdict($msg->packet_id(), NF_ACCEPT)
$queue->set_mode(IPQ_COPY_PACKET, 2048);
IPTables::IPv4::IPQueue->errstr;
undef $queue;
DESCRIPTION
Perlipq (IPTables::IPv4::IPQueue) is a Perl extension for iptables userspace packet queuing via libipq.
Packets may be selected from the stack via the iptables QUEUE target and passed to userspace. Perlipq allows these packets to be
manipulated in Perl and passed back to the stack.
More information on userspace packet queueing may be found in libipq(3).
CONSTANTS
Copy Mode
IPQ_COPY_META - Copy only packet metadata to userspace.
IPQ_COPY_PACKET - Copy metatdata and packet to userspace.
Packet Verdicts
NF_DROP - Ask kernel to drop packet.
NF_ACCEPT - Ask kernel to accept packet and continue processing.
ATTRIBUTES
None.
METHODS
new( [param => value, ... ] )
Constructor.
Creates userspace queuing object and sets the queuing mode.
Parameters:
protocol
copy_mode
copy_range
The protocol parameter, if provided, must be one of PF_INET or PF_INET6, for IPv4 and IPv6 packet queuing respectively. If no protocol
parameter is provided, the default is PF_INET.
The default copy mode is IPQ_COPY_META.
set_mode(mode [, range])
Set the queuing mode.
The mode parameter must be one of:
IPQ_COPY_META
IPQ_COPY_PACKET
When specifying IPQ_COPY_PACKET mode, the range parameter specifies the number of bytes of payload data to copy to userspace.
If the range is not provided and the mode is IPQ_COPY_PACKET, the range will default to zero. Typically, a range of 1500 will suffice.
This method is called by the constructor.
get_message([timeout])
Receives a packet message from the kernel, returning a tainted IPTables::IPv4::IPQueue::Packet object.
The optional timeout parameter may be used to specify a timeout for the operation in microseconds. This is implemented internally via
the select() syscall. A value of zero or no value means to wait indefinitely.
The returned object is a helper object with the following read only attributes:
packet_id ID of queued packet.
mark Netfilter mark value.
timestamp_sec Packet arrival time (seconds).
timestamp_usec Packet arrvial time (+useconds).
hook Netfilter hook we rode in on.
indev_name Name of incoming interface.
outdev_name Name of outgoing interface.
hw_protocol Hardware protocol.
hw_type Hardware media type.
hw_addrlen Hardware address length.
hw_addr Hardware address.
data_len Length of payload data.
payload Payload data.
Payload data, if present, is a scalar byte string suitable for use with packages such as NetPacket.
If the operation timed out, undef will be returned and the errstr() message will be 'Timeout'. See the sample dumper.pl script for a
simple example of how this may be handled.
set_verdict(id, verdict [, data_len, buf ])
Sets verdict on packet with specified id, and optionally sends modified packet data back to the kernel.
The verdict must be one of:
NF_DROP
NF_ACCEPT
close()
Destroys userpsace queue context and all associated resources.
This is called by the destructor, which means you can just do:
undef $queue;
instead.
errstsr()
Class method, returns an error message based on the most recent library error condition and global errno value.
EXAMPLE
package example;
use strict;
$^W = 1;
use IPTables::IPv4::IPQueue qw(:constants);
my ($queue, $msg);
$queue = new IPTables::IPv4::IPQueue(copy_mode => IPQ_COPY_META)
or die IPTables::IPv4::IPQueue->errstr;
$msg = $queue->get_message()
or die IPTables::IPv4::IPQueue->errstr;
$queue->set_verdict($msg->packet_id(), NF_ACCEPT) > 0
or die IPTables::IPv4::IPQueue->errstr;
CHANGES
o Support for timeouts in get_message() was added in version 1.24.
BUGS
None known.
COPYRIGHT
Copyright (c) 2000-2002 James Morris <jmorris@intercode.com.au>
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation,
Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
AUTHOR
James Morris <jmorris@intercode.com.au>
SEE ALSO iptables(8)libipq(3)NetPacket(3)
The example scripts, passer.pl, passer6.pl and dumper.pl.
perl v5.14.2 2011-11-15 IPQueue(3pm)