diff -Naur syslog-ng-2.0.5.orig/doc/Makefile.am syslog-ng-2.0.5/doc/Makefile.am
--- syslog-ng-2.0.5.orig/doc/Makefile.am	2007-04-19 21:37:16.000000000 +0200
+++ syslog-ng-2.0.5/doc/Makefile.am	2007-11-03 00:28:59.000000000 +0100
@@ -6,6 +6,7 @@
 	reference/syslog-ng.xml \
 	reference/syslog-ng.txt \
 	reference/syslog-ng.xsl \
+	reference/README.syslog-ng-anon \
 	examples/syslog-ng.conf.sample \
 	examples/syslog-ng.conf.solaris
 
diff -Naur syslog-ng-2.0.5.orig/doc/Makefile.in syslog-ng-2.0.5/doc/Makefile.in
--- syslog-ng-2.0.5.orig/doc/Makefile.in	2007-07-22 15:40:04.000000000 +0200
+++ syslog-ng-2.0.5/doc/Makefile.in	2007-11-03 00:28:59.000000000 +0100
@@ -135,6 +135,7 @@
 	reference/syslog-ng.xml \
 	reference/syslog-ng.txt \
 	reference/syslog-ng.xsl \
+	reference/README/syslog-ng-anon \
 	examples/syslog-ng.conf.sample \
 	examples/syslog-ng.conf.solaris
 
diff -Naur syslog-ng-2.0.5.orig/doc/reference/README.syslog-ng-anon syslog-ng-2.0.5/doc/reference/README.syslog-ng-anon
--- syslog-ng-2.0.5.orig/doc/reference/README.syslog-ng-anon	1970-01-01 01:00:00.000000000 +0100
+++ syslog-ng-2.0.5/doc/reference/README.syslog-ng-anon	2007-11-03 00:42:04.000000000 +0100
@@ -0,0 +1,88 @@
+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:
+ 	. Debian package syslog-ng_2.0.5-2
+
+  To use this patch, obtain the source for syslog-ng
+  (apt-get source syslog-ng) and the
+  syslog-ng-anon patch (http://dev.riseup.net/patches/syslog-ng/). 
+  Apply the patch the patch:
+
+  % cd syslog-ng-2.0.5
+  % patch -p1 < ../syslog-ng-anon.diff
+ 
+  Then compile and install syslog-ng:
+
+  % dpkg-buildpackage -rfakeroot -b
+  % dpkg -i ../syslog-ng_2.0.5-2_i386.deb
+
+ 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 -Naur syslog-ng-2.0.5.orig/src/cfg-grammar.y syslog-ng-2.0.5/src/cfg-grammar.y
--- syslog-ng-2.0.5.orig/src/cfg-grammar.y	2007-05-21 19:21:07.000000000 +0200
+++ syslog-ng-2.0.5/src/cfg-grammar.y	2007-11-03 00:28:59.000000000 +0100
@@ -107,7 +107,7 @@
 %token KW_USE_TIME_RECVD
 
 /* filter items*/
-%token KW_FACILITY KW_LEVEL KW_HOST KW_MATCH KW_NETMASK
+%token KW_FACILITY KW_LEVEL KW_HOST KW_MATCH KW_NETMASK KW_STRIP KW_REPLACE
 
 /* yes/no switches */
 %token KW_YES KW_NO
@@ -802,6 +802,8 @@
 	| KW_PROGRAM '(' string ')'		{ $$ = filter_prog_new($3); free($3); }
 	| KW_HOST '(' string ')'		{ $$ = filter_host_new($3); free($3); }	
 	| KW_MATCH '(' string ')'		{ $$ = filter_match_new($3); free($3); }
+	| KW_STRIP '(' string ')'               { $$ = filter_strip_new($3); free($3); }
+	| KW_REPLACE '(' string string ')'      { $$ = filter_replace_new($3, $4); free($3); free($4); }
 	| KW_FILTER '(' string ')'		{ $$ = filter_call_new($3, configuration); free($3); }
 	| KW_NETMASK '(' string ')'		{ $$ = filter_netmask_new($3); free($3); }
 	;
@@ -907,4 +909,4 @@
   last_reader_options = NULL;
   last_writer_options = NULL;
   last_template = NULL;
-}
\ No newline at end of file
+}
diff -Naur syslog-ng-2.0.5.orig/src/cfg-lex.l syslog-ng-2.0.5/src/cfg-lex.l
--- syslog-ng-2.0.5.orig/src/cfg-lex.l	2007-05-21 19:21:07.000000000 +0200
+++ syslog-ng-2.0.5/src/cfg-lex.l	2007-11-03 00:28:59.000000000 +0100
@@ -165,6 +165,8 @@
         { "host",               KW_HOST },
         { "match",		KW_MATCH },
         { "netmask",		KW_NETMASK },
+        { "strip",              KW_STRIP },
+        { "replace",            KW_REPLACE },
 
 	/* on/off switches */
 	{ "yes",		KW_YES },
diff -Naur syslog-ng-2.0.5.orig/src/filter.c syslog-ng-2.0.5/src/filter.c
--- syslog-ng-2.0.5.orig/src/filter.c	2007-05-21 19:21:07.000000000 +0200
+++ syslog-ng-2.0.5/src/filter.c	2007-11-03 00:30:22.000000000 +0100
@@ -226,6 +226,7 @@
 typedef struct _FilterRE
 {
   FilterExprNode super;
+  GString *replace;
   regex_t regex;
 } FilterRE;
 
@@ -310,6 +311,9 @@
 filter_re_free(FilterExprNode *s)
 {
   FilterRE *self = (FilterRE *) s;
+
+  if (self->replace != NULL)
+	  g_string_free(self->replace, TRUE);
   
   regfree(&self->regex);
   g_free(s);
@@ -494,3 +498,89 @@
   self->super.eval = filter_netmask_eval;
   return &self->super;
 }
+
+FilterExprNode *
+filter_strip_new(const gchar *re)
+{
+	if (g_ascii_strcasecmp(re, "ips") == 0)
+		return filter_replace_new(re, "0.0.0.0");
+	return filter_replace_new(re, "----");
+}
+
+#define FMIN(a, b) (a) < (b) ? (a) : (b)
+#define NEW_MSG_SIZE 2048
+
+static gboolean
+filter_replace_eval(FilterExprNode *s, LogMessage *log)
+{
+  FilterRE *self = (FilterRE *) s;
+  gchar *buffer = log->msg.str;
+  gint snippet_size;
+  regmatch_t pmatch;
+  gchar new_msg[NEW_MSG_SIZE];
+  gchar *new_msg_max = new_msg + NEW_MSG_SIZE;
+  gchar *new_msg_ptr = new_msg;
+  gint replace_length = self->replace->len;
+  gint error;
+
+  error = regexec(&self->regex, buffer, 1, &pmatch, 0);
+  if (error)
+    return TRUE;
+  while (!error)
+    {
+      /* 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 */
+      snippet_size = FMIN(replace_length, new_msg_max - new_msg_ptr);
+      memcpy(new_msg_ptr, self->replace->str, 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 message */
+  snippet_size = log->msg.len - (buffer - log->msg.str) + 1;
+  snippet_size = FMIN(snippet_size, new_msg_max - new_msg_ptr);
+  memcpy(new_msg_ptr, buffer, snippet_size);
+  new_msg[NEW_MSG_SIZE-1] = '\0';
+			
+  g_string_erase(&(log->msg), 0, -1);
+  g_string_append(&(log->msg), new_msg);
+			
+  return TRUE;
+}
+			
+FilterExprNode *
+filter_replace_new(const gchar *re, const gchar *replacement)
+{
+  FilterRE *self = g_new0(FilterRE, 1);
+  gint regerr;
+		
+  if (!g_ascii_strcasecmp(re, "ips"))
+    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)
+    {
+      gchar errorbuf[256];
+      regerror(regerr, &self->regex, errorbuf, sizeof(errorbuf));
+      msg_error("Error compiling regular expression:",
+                evt_tag_str("re", re),
+                evt_tag_str("error", errorbuf),
+                NULL);
+      g_free(self);
+      return NULL;
+    }
+				
+  self->replace = g_string_new(replacement);
+  self->super.eval = filter_replace_eval;
+  self->super.free_fn = filter_re_free;
+		
+  return &self->super;
+}
+
diff -Naur syslog-ng-2.0.5.orig/src/filter.h syslog-ng-2.0.5/src/filter.h
--- syslog-ng-2.0.5.orig/src/filter.h	2007-05-21 19:21:07.000000000 +0200
+++ syslog-ng-2.0.5/src/filter.h	2007-11-03 00:28:59.000000000 +0100
@@ -54,6 +54,8 @@
 FilterExprNode *filter_match_new(gchar *re);
 FilterExprNode *filter_call_new(gchar *rule, struct _GlobalConfig *cfg);
 FilterExprNode *filter_netmask_new(gchar *cidr);
+FilterExprNode *filter_strip_new(const gchar *re);
+FilterExprNode *filter_replace_new(const gchar *re, const gchar *replacement);
 
 typedef struct _LogFilterRule
 {