Linux: iptables Logs in Gentoo

The Gentoo linux distro does not separate the iptables logs in a separate file. This post is to help achieve the separate log file for iptables using either syslog-ng or ulogd daemon.

syslog-ng

The first way is to modify the syslog-ng configuration. The configuration in /etc/syslog-ng/syslog-ng.conf looks as follows:

Version 3.4

@version: 3.4
# Copyright 1999-2011 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: /var/cvsroot/gentoo-x86/app-admin/syslog-ng/files/3.4/syslog-ng.conf.gentoo.hardened,v 1.1 2013/04/28 04:50:34 mr_bones_ Exp $

# https://bugs.gentoo.org/show_bug.cgi?id=426814
@include "scl.conf"

#
# Syslog-ng configuration file, compatible with default hardened installations.
#

options {
	threaded(yes);
	chain_hostnames(no);
	stats_freq(43200);
};

source src {
    unix-dgram("/dev/log");
    internal();
};
source kernsrc {
    file("/proc/kmsg");
};

#source net { udp(); };
#log { source(net); destination(net_logs); };
#destination net_logs { file("/var/log/HOSTS/$HOST/$YEAR$MONTH$DAY.log"); };

destination authlog { file("/var/log/auth.log"); };
destination _syslog { file("/var/log/syslog"); };
destination cron { file("/var/log/cron.log"); };
destination daemon { file("/var/log/daemon.log"); };
destination kern { file("/var/log/kern.log"); file("/dev/tty12"); };
destination lpr { file("/var/log/lpr.log"); };
destination user { file("/var/log/user.log"); };
destination uucp { file("/var/log/uucp.log"); };
#destination ppp { file("/var/log/ppp.log"); };
destination mail { file("/var/log/mail.log"); };

destination avc { file("/var/log/avc.log"); };
destination audit { file("/var/log/audit.log"); };
destination pax { file("/var/log/pax.log"); };
destination grsec { file("/var/log/grsec.log"); };

destination mailinfo { file("/var/log/mail.info"); };
destination mailwarn { file("/var/log/mail.warn"); };
destination mailerr { file("/var/log/mail.err"); };

destination newscrit { file("/var/log/news/news.crit"); };
destination newserr { file("/var/log/news/news.err"); };
destination newsnotice { file("/var/log/news/news.notice"); };

destination debug { file("/var/log/debug"); };
destination messages { file("/var/log/messages"); };
destination console { usertty("root"); };
destination console_all { file("/dev/tty12"); };
#destination loghost { udp("loghost" port(999)); };

destination xconsole { pipe("/dev/xconsole"); };

destination iptables { file("/var/log/iptables.log"); };

filter f_auth { facility(auth); };
filter f_authpriv { facility(auth, authpriv); };
filter f_syslog { not facility(authpriv, mail); };
filter f_cron { facility(cron); };
filter f_daemon { facility(daemon); };
filter f_kern { facility(kern);
        and not filter(f_iptables); };
filter f_lpr { facility(lpr); };
filter f_mail { facility(mail); };
filter f_user { facility(user); };
filter f_uucp { facility(uucp); };
#filter f_ppp { facility(ppp); };
filter f_news { facility(news); };
filter f_debug { not facility(auth, authpriv, news, mail); };
filter f_messages { level(info..warn)
        and not facility(auth, authpriv, mail, news);
        and not program(syslog-ng) and not filter(f_iptables); };

filter f_emergency { level(emerg); };

filter f_info { level(info); };

filter f_notice { level(notice); };
filter f_warn { level(warn); };
filter f_crit { level(crit); };
filter f_err { level(err); };

filter f_avc { message(".*avc: .*"); };
filter f_audit { message("^(\[.*..*] |)audit.*") and not message(".*avc: .*"); };
filter f_pax { message("^(\[.*..*] |)PAX:.*"); };
filter f_grsec { message("^(\[.*..*] |)grsec:.*"); };

filter f_iptables { facility(kern) and match("IN=" value("MESSAGE")) and match("OUT=" value("MESSAGE")); };

log { source(src); filter(f_authpriv); destination(authlog); };
log { source(src); filter(f_syslog); destination(_syslog); };
log { source(src); filter(f_cron); destination(cron); };
log { source(src); filter(f_daemon); destination(daemon); };
log { source(kernsrc); filter(f_kern); destination(kern); };
log { source(src); filter(f_lpr); destination(lpr); };
log { source(src); filter(f_mail); destination(mail); };
log { source(src); filter(f_user); destination(user); };
log { source(src); filter(f_uucp); destination(uucp); };
log { source(kernsrc); filter(f_pax); destination(pax); };
log { source(kernsrc); filter(f_grsec); destination(grsec); };
log { source(kernsrc); filter(f_audit); destination(audit); };
log { source(kernsrc); filter(f_avc); destination(avc); };
log { source(src); filter(f_mail); filter(f_info); destination(mailinfo); };
log { source(src); filter(f_mail); filter(f_warn); destination(mailwarn); };
log { source(src); filter(f_mail); filter(f_err); destination(mailerr); };
log { source(src); filter(f_news); filter(f_crit); destination(newscrit); };
log { source(src); filter(f_news); filter(f_err); destination(newserr); };
log { source(src); filter(f_news); filter(f_notice); destination(newsnotice); };
log { source(src); filter(f_debug); destination(debug); };
log { source(src); filter(f_messages); destination(messages); };
log { source(src); filter(f_emergency); destination(console); };
#log { source(src); filter(f_ppp); destination(ppp); };
log { source(src); destination(console_all); };

log { source(kernsrc); filter(f_iptables); destination(iptables); };

Now restart the syslog-ng daemon and check your /var/log/iptables.log and other log files. Inspiration taken from Gentoo Forums.

Version 3.3

@version: 3.3
#
# /etc/syslog-ng/syslog-ng.conf
#

options {
  stats_freq (0);
  flush_lines (0);
  time_reopen (10);
  log_fifo_size (10000);
  chain_hostnames (off);
  use_dns (no);
  use_fqdn (no);
  create_dirs (no);
  keep_hostname (yes);
  perm(0640);
};

source src {
  unix-dgram("/dev/log");
  internal();
  file("/proc/kmsg");
};

destination d_authlog { file("/var/log/auth.log"); };
destination d_syslog { file("/var/log/syslog.log"); };
destination d_cron { file("/var/log/crond.log"); };
destination d_daemon { file("/var/log/daemon.log"); };
destination d_kernel { file("/var/log/kernel.log"); };
destination d_lpr { file("/var/log/lpr.log"); };
destination d_user { file("/var/log/user.log"); };
destination d_uucp { file("/var/log/uucp.log"); };
destination d_mail { file("/var/log/mail.log"); };
destination d_news { file("/var/log/news.log"); };
destination d_ppp { file("/var/log/ppp.log"); };
destination d_debug { file("/var/log/debug.log"); };
destination d_messages { file("/var/log/messages.log"); };
destination d_errors { file("/var/log/errors.log"); };
destination d_everything { file("/var/log/everything.log"); };
destination d_iptables { file("/var/log/iptables.log"); };
destination d_acpid { file("/var/log/acpid.log"); };
destination d_console { usertty("root"); };

# Log everything to tty12
destination console_all { file("/dev/tty12"); };

filter f_auth { facility(auth); };
filter f_authpriv { facility(auth, authpriv); };
filter f_syslog { program(syslog-ng); };
filter f_cron { facility(cron); };
filter f_daemon { facility(daemon); };
filter f_kernel { facility(kern) and not filter(f_iptables); };
filter f_lpr { facility(lpr); };
filter f_mail { facility(mail); };
filter f_news { facility(news); };
filter f_user { facility(user); };
filter f_uucp { facility(uucp); };
filter f_ppp { facility(local2); };
filter f_debug { not facility(auth, authpriv, news, mail); };
filter f_messages { level(info..warn) and not facility(auth, authpriv, mail, news, cron) and not program(syslog-ng) and not filter(f_iptables); };
filter f_everything { level(debug..emerg) and not facility(auth, authpriv); };
filter f_emergency { level(emerg); };
filter f_info { level(info); };
filter f_notice { level(notice); };
filter f_warn { level(warn); };
filter f_crit { level(crit); };
filter f_err { level(err); };
filter f_iptables { match("IN=" value("MESSAGE")) and match("OUT=" value("MESSAGE")); };
filter f_acpid { program("acpid"); };

log { source(src); filter(f_acpid); destination(d_acpid); };
log { source(src); filter(f_authpriv); destination(d_authlog); };
log { source(src); filter(f_syslog); destination(d_syslog); };
log { source(src); filter(f_cron); destination(d_cron); };
log { source(src); filter(f_daemon); destination(d_daemon); };
log { source(src); filter(f_kernel); destination(d_kernel); };
log { source(src); filter(f_lpr); destination(d_lpr); };
log { source(src); filter(f_mail); destination(d_mail); };
log { source(src); filter(f_news); destination(d_news); };
log { source(src); filter(f_ppp); destination(d_ppp); };
log { source(src); filter(f_user); destination(d_user); };
log { source(src); filter(f_uucp); destination(d_uucp); };
#log { source(src); filter(f_debug); destination(d_debug); };
log { source(src); filter(f_messages); destination(d_messages); };
log { source(src); filter(f_err); destination(d_errors); };
log { source(src); filter(f_emergency); destination(d_console); };
log { source(src); filter(f_everything); destination(d_everything); };
log { source(src); filter(f_iptables); destination(d_iptables); };

# Log everything to tty12
#log { source(src); destination(console_all); };

Now restart the syslog-ng daemon and check your /var/log/iptables.log and other log files. And yes, you’re right, this config file was taken from Archlinux distro 🙂

ulogd

Another option is to install the ulogd daemon:

emerge -av app-admin/ulogd

Then edit the configuration file /etc/ulogd.conf and change to:

[LOGEMU]
#file="/var/log/ulogd.syslogemu"
file="/var/log/iptables.log"

It is necessary to change the LOG statements in the iptables configuration to ULOG.
Don’t forget to add into the default runlevel

rc-update add ulogd default

That’s it.

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