more DoS prevention: add packet_limit option to apply a hard limit to downstream packets per session
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bodea
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7 changed files with 79 additions and 17 deletions
4
Changes
4
Changes
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@ -1,10 +1,12 @@
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* Fri Jan 7 2005 Brendan O'Dea <bod@optusnet.com.au> 2.1.0
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* Mon Jan 10 2005 Brendan O'Dea <bod@optusnet.com.au> 2.1.0
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- Add IPv6 support from Jonathan McDowell (work in progress).
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- Add CHAP support from Jordan Hrycaj (work in progress).
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- Sanity check that cluster_send_session is not called from a child
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process.
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- Throttle outgoing LASTSEEN packets to at most one per second for a
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given seq#.
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- More DoS prevention: add packet_limit option to apply a hard limit
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to downstream packets per session.
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- Use bounds-checking lookup functions for string constants.
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- Add enum for RADIUS codes.
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- Make "call_" prefix implict in CSTAT() macro.
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@ -307,6 +307,13 @@ Keep all pages mapped by the l2tpns process in memory.
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Maximum number of host unreachable ICMP packets to send per second.
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</LI>
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<LI><B>packet_limit</B> (int><BR>
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Maximum number of packets of downstream traffic to be handled each
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tenth of a second per session. If zero, no limit is applied (default:
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0). Intended as a DoS prevention mechanism and not a general
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throttling control (packets are dropped, not queued).
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</LI>
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<LI><B>cluster_address</B> (ip address)<BR>
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Multicast cluster address (default: 239.192.13.13). See the section
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on <A HREF="#Clustering">Clustering</A> for more information.
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@ -2,7 +2,7 @@
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.de Id
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.ds Dt \\$4 \\$5
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..
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.Id $Id: startup-config.5,v 1.3 2004/11/29 06:29:28 bodea Exp $
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.Id $Id: startup-config.5,v 1.4 2005/01/10 07:17:37 bodea Exp $
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.TH STARTUP-CONFIG 5 "\*(Dt" L2TPNS "File Formats and Conventions"
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.SH NAME
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startup\-config \- configuration file for l2tpns
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@ -160,6 +160,12 @@ process in memory.
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.B icmp_rate
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Maximum number of host unreachable ICMP packets to send per second.
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.TP
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.B packet_limit
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Maximum number of packets of downstream traffic to be handled each
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tenth of a second per session. If zero, no limit is applied (default:
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0). Intended as a DoS prevention mechanism and not a general
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throttling control (packets are dropped, not queued).
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.TP
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.B cluster_address
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Multicast cluster address (default: 239.192.13.13).
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.TP
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17
cli.c
17
cli.c
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@ -2,7 +2,7 @@
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// vim: sw=8 ts=8
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char const *cvs_name = "$Name: $";
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char const *cvs_id_cli = "$Id: cli.c,v 1.45 2005/01/07 07:15:10 bodea Exp $";
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char const *cvs_id_cli = "$Id: cli.c,v 1.46 2005/01/10 07:17:37 bodea Exp $";
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#include <stdio.h>
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#include <stdarg.h>
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@ -646,23 +646,24 @@ static int cmd_show_counters(struct cli_def *cli, char *command, char **argv, in
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if (CLI_HELP_REQUESTED)
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return CLI_HELP_NO_ARGS;
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cli_print(cli, "%-10s %-8s %-10s %-8s", "Ethernet", "Bytes", "Packets", "Errors");
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cli_print(cli, "%-10s %8u %8u %8u", "RX",
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cli_print(cli, "%-10s %10s %8s %8s %8s", "Ethernet", "Bytes", "Packets", "Errors", "Dropped");
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cli_print(cli, "%-10s %10u %8u %8u %8u", "RX",
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GET_STAT(tun_rx_bytes),
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GET_STAT(tun_rx_packets),
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GET_STAT(tun_rx_errors));
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cli_print(cli, "%-10s %8u %8u %8u", "TX",
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GET_STAT(tun_rx_errors),
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GET_STAT(tun_rx_dropped));
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cli_print(cli, "%-10s %10u %8u %8u", "TX",
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GET_STAT(tun_tx_bytes),
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GET_STAT(tun_tx_packets),
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GET_STAT(tun_tx_errors));
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cli_print(cli, "");
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cli_print(cli, "%-10s %-8s %-10s %-8s %-8s", "Tunnel", "Bytes", "Packets", "Errors", "Retries");
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cli_print(cli, "%-10s %8u %8u %8u", "RX",
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cli_print(cli, "%-10s %10s %8s %8s %8s", "Tunnel", "Bytes", "Packets", "Errors", "Retries");
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cli_print(cli, "%-10s %10u %8u %8u", "RX",
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GET_STAT(tunnel_rx_bytes),
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GET_STAT(tunnel_rx_packets),
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GET_STAT(tunnel_rx_errors));
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cli_print(cli, "%-10s %8u %8u %8u %8u", "TX",
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cli_print(cli, "%-10s %10u %8u %8u %8u", "TX",
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GET_STAT(tunnel_tx_bytes),
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GET_STAT(tunnel_tx_packets),
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GET_STAT(tunnel_tx_errors),
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44
l2tpns.c
44
l2tpns.c
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@ -4,7 +4,7 @@
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// Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced
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// vim: sw=8 ts=8
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char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.75 2005/01/07 07:18:33 bodea Exp $";
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char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.76 2005/01/10 07:17:37 bodea Exp $";
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#include <arpa/inet.h>
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#include <assert.h>
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@ -120,6 +120,7 @@ config_descriptt config_values[] = {
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CONFIG("scheduler_fifo", scheduler_fifo, BOOL),
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CONFIG("lock_pages", lock_pages, BOOL),
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CONFIG("icmp_rate", icmp_rate, INT),
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CONFIG("packet_limit", max_packets, INT),
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CONFIG("cluster_address", cluster_address, IPv4),
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CONFIG("cluster_interface", cluster_interface, STRING),
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CONFIG("cluster_hb_interval", cluster_hb_interval, INT),
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@ -784,13 +785,13 @@ static void processipout(uint8_t * buf, int len)
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if (len < MIN_IP_SIZE)
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{
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LOG(1, 0, 0, "Short IP, %d bytes\n", len);
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STAT(tunnel_tx_errors);
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STAT(tun_rx_errors);
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return;
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}
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if (len >= MAXETHER)
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{
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LOG(1, 0, 0, "Oversize IP packet %d bytes\n", len);
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STAT(tunnel_tx_errors);
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STAT(tun_rx_errors);
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return;
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}
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@ -828,6 +829,43 @@ static void processipout(uint8_t * buf, int len)
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t = session[s].tunnel;
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sp = &session[s];
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// DoS prevention: enforce a maximum number of packets per 0.1s for a session
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if (config->max_packets > 0)
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{
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if (sess_count[s].last_packet_out == TIME)
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{
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int max = config->max_packets;
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// All packets for throttled sessions are handled by the
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// master, so further limit by using the throttle rate.
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// A bit of a kludge, since throttle rate is in kbps,
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// but should still be generous given our average DSL
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// packet size is 200 bytes: a limit of 28kbps equates
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// to around 180 packets per second.
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if (!config->cluster_iam_master && sp->throttle_out && sp->throttle_out < max)
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max = sp->throttle_out;
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if (++sess_count[s].packets_out > max)
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{
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sess_count[s].packets_dropped++;
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return;
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}
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}
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else
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{
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if (sess_count[s].packets_dropped)
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{
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INC_STAT(tun_rx_dropped, sess_count[s].packets_dropped);
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LOG(2, s, t, "Possible DoS attack on %s (%s); dropped %u packets.",
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fmtaddr(ip, 0), sp->user, sess_count[s].packets_dropped);
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}
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sess_count[s].last_packet_out = TIME;
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sess_count[s].packets_out = 1;
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sess_count[s].packets_dropped = 0;
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}
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}
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// run access-list if any
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if (session[s].filter_out && !ip_filter(buf, len, session[s].filter_out - 1))
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return;
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12
l2tpns.h
12
l2tpns.h
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@ -1,5 +1,5 @@
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// L2TPNS Global Stuff
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// $Id: l2tpns.h,v 1.51 2005/01/07 07:17:13 bodea Exp $
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// $Id: l2tpns.h,v 1.52 2005/01/10 07:17:37 bodea Exp $
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#ifndef __L2TPNS_H__
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#define __L2TPNS_H__
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@ -228,8 +228,14 @@ sessiont;
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typedef struct
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{
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// byte counters
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uint32_t cin;
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uint32_t cout;
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// DoS prevention
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clockt last_packet_out;
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uint32_t packets_out;
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uint32_t packets_dropped;
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} sessioncountt;
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#define SESSIONPFC 1 // PFC negotiated flags
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@ -333,6 +339,7 @@ struct Tstats
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uint32_t tun_tx_bytes;
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uint32_t tun_rx_errors;
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uint32_t tun_tx_errors;
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uint32_t tun_rx_dropped;
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uint32_t tunnel_rx_packets;
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uint32_t tunnel_tx_packets;
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@ -470,7 +477,8 @@ typedef struct
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int next_tbf; // Next HTB id available to use
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int scheduler_fifo; // If the system has multiple CPUs, use FIFO scheduling policy for this process.
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int lock_pages; // Lock pages into memory.
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int icmp_rate; // Max number of ICMP unreachable per second to send>
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int icmp_rate; // Max number of ICMP unreachable per second to send
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int max_packets; // DoS prevention: per session limit of packets/0.1s
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in_addr_t cluster_address; // Multicast address of cluster.
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// Send to this address to have everyone hear.
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@ -43,5 +43,5 @@ rm -rf %{buildroot}
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%attr(644,root,root) /usr/share/man/man[58]/*
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%changelog
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* Fri Jan 7 2005 Brendan O'Dea <bod@optusnet.com.au> 2.1.0-1
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* Mon Jan 10 2005 Brendan O'Dea <bod@optusnet.com.au> 2.1.0-1
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- 2.1.0 release, see /usr/share/doc/l2tpns-2.1.0/Changes
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