diff -uNr orig/syslog-ng-1.6.7/doc/Makefile.am new/syslog-ng-1.6.7/doc/Makefile.am
--- orig/syslog-ng-1.6.7/doc/Makefile.am	2005-03-04 09:58:08.000000000 -0600
+++ new/syslog-ng-1.6.7/doc/Makefile.am	2005-05-30 18:26:29.986769706 -0500
@@ -4,7 +4,7 @@
 
 EXTRA_DIST = $(man_MANS) stresstest.sh syslog-ng.old.txt	\
 	syslog-ng.conf.demo syslog-ng.conf.sample \
-	syslog-ng.conf.solaris 
-
+	syslog-ng.conf.solaris README.syslog-ng-anon \
+	syslog-ng-anon.conf
 
 
diff -uNr orig/syslog-ng-1.6.7/doc/Makefile.in new/syslog-ng-1.6.7/doc/Makefile.in
--- orig/syslog-ng-1.6.7/doc/Makefile.in	2005-04-09 05:50:58.000000000 -0500
+++ new/syslog-ng-1.6.7/doc/Makefile.in	2005-05-30 18:29:45.194741054 -0500
@@ -116,7 +116,9 @@
 
 EXTRA_DIST = $(man_MANS) stresstest.sh syslog-ng.old.txt	\
 	syslog-ng.conf.demo syslog-ng.conf.sample \
-	syslog-ng.conf.solaris 
+	syslog-ng.conf.solaris README.syslog-ng-anon \
+	syslog-ng-anon.conf
+
 
 subdir = doc
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
diff -uNr orig/syslog-ng-1.6.7/doc/README.syslog-ng-anon new/syslog-ng-1.6.7/doc/README.syslog-ng-anon
--- orig/syslog-ng-1.6.7/doc/README.syslog-ng-anon	1969-12-31 18:00:00.000000000 -0600
+++ new/syslog-ng-1.6.7/doc/README.syslog-ng-anon	2005-05-30 18:25:40.828858265 -0500
@@ -0,0 +1,93 @@
+syslog-ng-anon
+
+ This patch adds the capability to syslog-ng that allows you to strip
+ out any given regexp or all IP addresses from log messages before
+ they are written to disk. The goal is to give the system administrator
+ the means to implement site logging policies, by allowing them easy
+ control over exactly what data they retain in their logfiles,
+ regardless of what a particular daemon might think is best.
+
+Background:
+
+ Data retention has become a hot legal topic for ISPs and other Online
+ Service Providers (OSPs). There are many instances where it is preferable
+ to keep less information on users than is collected by default on many
+ systems. In the United States it is not currently required to retain
+ data on users of a server, but you may be required to provide all data
+ on a user which you have retained. OSPs can protect themselves from legal
+ hassles and added work by choosing what data they wish to retain.
+
+ From "Best Practices for Online Service Providers"
+ (http://www.eff.org/osp):
+
+  As an intermediary, the OSP [Online Service Provider] finds itself in
+  a position to collect and store detailed information about its users
+  and their online activities that may be of great interest to third
+  parties. The USA PATRIOT Act also provides the government with
+  expanded powers to request this information. As a result, OSP owners
+  must deal with requests from law enforcement and lawyers to hand over
+  private user information and logs. Yet, compliance with these demands
+  takes away from an OSP's goal of providing users with reliable,
+  secure network services. In this paper, EFF offers some suggestions,
+  both legal and technical, for best practices that balance the needs
+  of OSPs and their users' privacy and civil liberties.
+ 
+  Rather than scrubbing the information you don't want in logs, this patch
+  ensures that the information is never written to disk. Also, for those 
+  daemons which log through syslog facilities, this patch provides a 
+  convenient single configuration to limit what you wish to log.
+  
+  Here are some related links:
+  
+  Best Practices for Online Service Providers
+  http://www.eff.org/osp
+  http://www.eff.org/osp/20040819_OSPBestPractices.pdf
+  
+  EPIC International Data Retention Page
+  http://www.epic.org/privacy/intl/data_retention.html
+  
+  Working Paper on Usage Log Data Management (from Computer, Freedom, and 
+  Privacy conference) http://cryptome.org/usage-logs.htm
+  
+
+Installing syslog-ng-anon 
+  
+ Applying the patch
+
+  This patch has been tested against the following versions of syslog-ng:
+ 	. version 1.6.7
+ 	. Debian package syslog-ng_1.6.7-2
+
+
+  To use this patch, obtain the source for syslog-ng 
+  (http://www.balabit.com/downloads/syslog-ng/1.6/src/) and the latest
+  syslog-ng-anon patch (http://dev.riseup.net/patches/syslog-ng/). 
+  Uncompress the syslog-ng source and then apply the patch:
+
+  % tar -zxvf syslog-ng.tar.gz
+  % cd syslog-ng
+  % patch -p1 < syslog-ng-anon.diff
+ 
+  Then compile and install syslog-ng as normal.
+
+ Debian package
+
+  Alternately, you can install syslog-ng-anon from this repository:
+  deb http://deb.riseup.net/debian unstable main
+
+ How to use it
+
+  This patch adds the filter "strip". For example:
+
+ 	filter f_strip {strip(<regexp>);};
+
+  This will strip out all matches of the regular expression on logs to
+  which the filter is applied and replaces all matches with the fixed length
+  four dashes ("----").
+
+  In place of a regular expression, you can put "ips", which will replace all
+  internet addresses with 0.0.0.0. For example:
+
+ 	filter f_strip {strip(ips);};
+
+  You can alter what the replacement strings are by using replace:
diff -uNr orig/syslog-ng-1.6.7/doc/syslog-ng-anon.conf new/syslog-ng-1.6.7/doc/syslog-ng-anon.conf
--- orig/syslog-ng-1.6.7/doc/syslog-ng-anon.conf	1969-12-31 18:00:00.000000000 -0600
+++ new/syslog-ng-1.6.7/doc/syslog-ng-anon.conf	2005-05-30 18:25:40.828858265 -0500
@@ -0,0 +1,243 @@
+#
+# Configuration file for syslog-ng under Debian.
+# Customized for riseup.net using syslog-ng-anon patch
+# (http://dev.riseup.net/patches/syslog-ng/)
+#
+# see http://www.campin.net/syslog-ng/expanded-syslog-ng.conf
+# for examples.
+#
+# levels: emerg alert crit err warning notice info debug
+#
+
+############################################################
+## global options
+
+options {
+    chain_hostnames(0);
+    time_reopen(10);
+    time_reap(360);
+    sync(0);
+    log_fifo_size(2048);
+    create_dirs(yes);
+    group(adm);
+    perm(0640);
+    dir_perm(0755);
+    use_dns(no);
+};
+
+############################################################
+## universal source
+
+source s_all {
+    internal();
+    unix-stream("/dev/log");
+    file("/proc/kmsg" log_prefix("kernel: "));
+};
+
+############################################################
+## generic destinations
+
+destination df_facility_dot_info   { file("/var/log/$FACILITY.info");   };
+destination df_facility_dot_notice { file("/var/log/$FACILITY.notice"); };
+destination df_facility_dot_warn   { file("/var/log/$FACILITY.warn");   };
+destination df_facility_dot_err    { file("/var/log/$FACILITY.err");    };
+destination df_facility_dot_crit   { file("/var/log/$FACILITY.crit");   };
+
+############################################################
+## generic filters
+
+filter f_strip { strip(ips); };
+filter f_at_least_info   { level(info..emerg);   };
+filter f_at_least_notice { level(notice..emerg); };
+filter f_at_least_warn   { level(warn..emerg);   };
+filter f_at_least_err    { level(err..emerg);    };
+filter f_at_least_crit   { level(crit..emerg);   };
+
+############################################################
+## auth.log
+
+filter f_auth { facility(auth, authpriv); };
+destination df_auth { file("/var/log/auth.log"); };
+log {
+    source(s_all);
+    filter(f_auth);
+    destination(df_auth);
+};
+
+############################################################
+## daemon.log
+
+filter f_daemon { facility(daemon); };
+destination df_daemon { file("/var/log/daemon.log"); };
+log {
+    source(s_all);
+    filter(f_daemon);
+    destination(df_daemon);
+};
+
+############################################################
+## kern.log
+
+filter f_kern { facility(kern); };
+destination df_kern { file("/var/log/kern.log"); };
+log {
+    source(s_all);
+    filter(f_kern);
+    destination(df_kern);
+};
+
+############################################################
+## user.log
+
+filter f_user { facility(user); };
+destination df_user { file("/var/log/user.log"); };
+log {
+    source(s_all);
+    filter(f_user);
+    destination(df_user);
+};
+
+############################################################
+## sympa.log
+
+filter f_sympa { program("^(sympa|bounced|archived|task_manager)"); };
+destination d_sympa { file("/var/log/sympa.log"); };
+log {
+	source(s_all);
+	filter(f_sympa);
+	destination(d_sympa);
+	flags(final);
+};
+
+############################################################
+## wwsympa.log
+
+filter f_wwsympa { program("^wwsympa"); };
+destination d_wwsympa { file("/var/log/wwsympa.log"); };
+log {
+	source(s_all);
+	filter(f_wwsympa);
+	filter(f_strip);
+	destination(d_wwsympa);
+	flags(final);
+};
+
+############################################################
+## ldap.log
+
+filter f_ldap { program("slapd"); };
+destination d_ldap { file("/var/log/ldap.log"); };
+log {
+	source(s_all);
+	filter(f_ldap);
+	destination(d_ldap);
+	flags(final);
+};
+
+############################################################
+## postfix.log
+
+# special source because of chroot jail
+#source s_postfix { unix-stream("/var/spool/postfix/dev/log" keep-alive(yes)); }; 
+filter f_postfix { program("^postfix/"); };
+destination d_postfix { file("/var/log/postfix.log"); };
+log {
+	source(s_all);
+	filter(f_postfix);
+	filter(f_strip);
+	destination(d_postfix);
+	flags(final);
+};
+
+############################################################
+## courier.log
+
+filter f_courier { program("courier|imap|pop"); };
+destination d_courier { file("/var/log/courier.log"); };
+log {
+	source(s_all);
+	filter(f_courier);
+	filter(f_strip);
+	destination(d_courier);
+	flags(final);
+};
+
+############################################################
+## maildrop.log
+
+filter f_maildrop { program("^maildrop"); };
+destination d_maildrop { file("/var/log/maildrop.log"); };
+log {
+	source(s_all);
+	filter(f_maildrop);
+	destination(d_courier);
+	flags(final);
+};
+
+############################################################
+## mail.log
+
+filter f_mail { facility(mail); };
+destination df_mail { file("/var/log/mail.log"); };
+
+log {
+    source(s_all);
+    filter(f_mail);
+    destination(df_mail);
+};
+
+############################################################
+## messages.log
+
+filter f_messages {
+	level(debug,info,notice)
+	and not facility(auth,authpriv,daemon,mail,user,kern);
+};
+destination df_messages { file("/var/log/messages.log"); };
+log {
+    source(s_all);
+    filter(f_messages);
+    destination(df_messages);
+};
+
+############################################################
+## errors.log
+
+filter f_errors {
+	level(warn,err,crit,alert,emerg)
+	and not facility(auth,authpriv,daemon,mail,user,kern);
+};
+destination df_errors { file("/var/log/errors.log"); };
+log {
+	source(s_all);
+	filter(f_errors);
+	destination(df_errors);
+};
+
+############################################################
+## emergencies
+
+filter f_emerg { level(emerg); };
+destination du_all { usertty("*"); };
+log {
+	source(s_all);
+	filter(f_emerg);
+	destination(du_all);
+};
+
+############################################################
+## console messages
+
+filter f_xconsole {
+    facility(daemon,mail)
+    or level(debug,info,notice,warn)
+    or (facility(news)
+    and level(crit,err,notice));
+};
+destination dp_xconsole { pipe("/dev/xconsole"); };
+log {
+    source(s_all);
+    filter(f_xconsole);
+    destination(dp_xconsole);
+};
+
diff -uNr orig/syslog-ng-1.6.7/src/cfg-grammar.y new/syslog-ng-1.6.7/src/cfg-grammar.y
--- orig/syslog-ng-1.6.7/src/cfg-grammar.y	2004-09-17 04:21:06.000000000 -0500
+++ new/syslog-ng-1.6.7/src/cfg-grammar.y	2005-05-30 18:25:40.826858634 -0500
@@ -89,7 +89,7 @@
 %token KW_REMOVE_IF_OLDER KW_LOG_PREFIX KW_PAD_SIZE
 
 /* filter items*/
-%token KW_FACILITY KW_LEVEL KW_NETMASK KW_HOST KW_MATCH
+%token KW_FACILITY KW_LEVEL KW_NETMASK KW_HOST KW_MATCH KW_STRIP KW_REPLACE
 
 /* yes/no switches */
 %token KW_YES KW_NO
@@ -669,6 +669,8 @@
 	| KW_NETMASK '(' string ')'             { $$ = make_filter_netmask($3); free($3); }
 	| KW_HOST '(' string ')'		{ $$ = make_filter_host($3); free($3); }	
 	| KW_MATCH '(' string ')'		{ $$ = make_filter_match($3); free($3); }
+	| KW_STRIP '(' string ')'		{ $$ = make_filter_strip($3); free($3); }
+	| KW_REPLACE '(' string string ')'		{ $$ = make_filter_replace($3,$4); free($3); free($4); }
 	| KW_FILTER '(' string ')'		{ $$ = make_filter_call($3); free($3); }
 	;
 
diff -uNr orig/syslog-ng-1.6.7/src/cfg-lex.l new/syslog-ng-1.6.7/src/cfg-lex.l
--- orig/syslog-ng-1.6.7/src/cfg-lex.l	2005-05-30 18:27:50.829842715 -0500
+++ new/syslog-ng-1.6.7/src/cfg-lex.l	2005-05-30 18:25:40.827858450 -0500
@@ -140,6 +140,8 @@
 	{ "netmask",            KW_NETMASK },
         { "host",               KW_HOST },
         { "match",		KW_MATCH },
+        { "strip",		KW_STRIP },
+        { "replace",	KW_REPLACE },
 
 	/* on/off switches */
 	{ "yes",		KW_YES },
diff -uNr orig/syslog-ng-1.6.7/src/filters.c new/syslog-ng-1.6.7/src/filters.c
--- orig/syslog-ng-1.6.7/src/filters.c	2004-01-13 12:08:02.000000000 -0600
+++ new/syslog-ng-1.6.7/src/filters.c	2005-05-30 18:25:40.827858450 -0500
@@ -163,6 +163,7 @@
      (name filter_expr_re)
      (super filter_expr_node)
      (vars
+       (replace string)
        (regex special-struct regex_t #f free_regexp)))
 */
 
@@ -226,6 +227,78 @@
 	return &self->super;
 }
 
+struct filter_expr_node *make_filter_strip(const char *re)
+{
+	if (strcasecmp(re,"ips") == 0)
+		return make_filter_replace(re,"0.0.0.0");
+	else
+		return make_filter_replace(re,"----");
+}
+
+#define FMIN(a,b) (a)<(b) ? (a):(b)
+
+static int do_filter_replace(struct filter_expr_node *c, 
+			   struct log_filter *rule UNUSED,
+			   struct log_info *log)
+{
+	CAST(filter_expr_re, self, c);
+	char * buffer = log->msg->data;
+	int snippet_size;
+	regmatch_t pmatch;
+	char new_msg[2048];
+	char * new_msg_max = new_msg+2048;
+	char * new_msg_ptr = new_msg;
+	int replace_length = strlen(self->replace->data);
+	
+	int error = regexec(&self->regex, buffer, 1, &pmatch, 0);
+	if (error != 0) return 1;
+	while (error==0) {
+		/* copy string snippet which preceeds matched text */
+		snippet_size = FMIN(pmatch.rm_so, new_msg_max-new_msg_ptr);
+		memcpy(new_msg_ptr, buffer, snippet_size);
+		new_msg_ptr += snippet_size;
+
+		/* copy replacement string */
+		snippet_size = FMIN(replace_length, new_msg_max-new_msg_ptr);
+		memcpy(new_msg_ptr, self->replace->data, snippet_size);
+		new_msg_ptr += snippet_size;
+
+		/* search for next match */
+		buffer += pmatch.rm_eo;
+		error = regexec (&self->regex, buffer, 1, &pmatch, REG_NOTBOL);
+	}
+	/* copy the rest of the old msg */
+	snippet_size = FMIN(strlen(buffer),new_msg_max-new_msg_ptr);
+	memcpy(new_msg_ptr, buffer, snippet_size); 
+	new_msg_ptr += snippet_size;
+
+	ol_string_free(log->msg);
+	log->msg = c_format_cstring("%s", new_msg_ptr-new_msg,new_msg);
+	return 1;
+}
+
+struct filter_expr_node *make_filter_replace(const char *re, const char *replacement)
+{
+	int regerr;
+	NEW(filter_expr_re, self);
+	self->super.eval = do_filter_replace;
+	self->replace = format_cstring(replacement);
+	
+	if (strcasecmp(re,"ips") == 0) {
+		re = "(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])([\\.\\-](25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])){3}";
+	}
+	regerr = regcomp(&self->regex, re, REG_ICASE | REG_EXTENDED);
+	if (regerr) {
+		char errorbuf[256];
+		regerror(regerr, &self->regex, errorbuf, sizeof(errorbuf));
+		werror("Error compiling regular expression: \"%z\" (%z)\n", re, errorbuf);
+		KILL(self);
+		return NULL;
+	}
+
+	return &self->super;
+}
+
 static int do_filter_prog(struct filter_expr_node *c, 
 			  struct log_filter *rule UNUSED,
 			  struct log_info *log)
diff -uNr orig/syslog-ng-1.6.7/src/filters.c.x new/syslog-ng-1.6.7/src/filters.c.x
--- orig/syslog-ng-1.6.7/src/filters.c.x	2004-09-03 05:26:08.000000000 -0500
+++ new/syslog-ng-1.6.7/src/filters.c.x	2005-05-30 18:25:40.827858450 -0500
@@ -47,6 +47,7 @@
 struct filter_expr_re
 {
   struct filter_expr_node super;
+  struct ol_string *replace;
   regex_t regex;
 };
 extern struct ol_class filter_expr_re_class;
@@ -56,6 +57,7 @@
 static void do_filter_expr_re_free(struct ol_object *o)
 {
   struct filter_expr_re *i = (struct filter_expr_re *) o;
+  ol_string_free(i->replace);
   free_regexp(&(i->regex));
 }
 
diff -uNr orig/syslog-ng-1.6.7/src/filters.h new/syslog-ng-1.6.7/src/filters.h
--- orig/syslog-ng-1.6.7/src/filters.h	2002-02-04 10:07:50.000000000 -0600
+++ new/syslog-ng-1.6.7/src/filters.h	2005-05-30 18:25:40.827858450 -0500
@@ -66,6 +66,8 @@
 struct filter_expr_node *make_filter_netmask(const char *nm);
 struct filter_expr_node *make_filter_host(const char *re);
 struct filter_expr_node *make_filter_match(const char *re);
+struct filter_expr_node *make_filter_strip(const char *re);
+struct filter_expr_node *make_filter_replace(const char *re, const char *replacement);
 struct filter_expr_node *make_filter_call(const char *name);
 
 #endif