v18

Adds support to use firewalld if it is running and updates documentation accordingly.

.gitignore

@@ -10,12 +10,9 @@ depcomp
 install-sh
 missing
 tallow
-tallow-*.tar.gz
+tallow-*.tar.*
 tallow-*/
-tallow.conf.5
-tallow.1
-tallow.1.html
-tallow.o
+*.o
 tallow.service
 *~
 DEADJOE

.travis.yml

@@ -1,24 +1,22 @@
+sudo: required
 dist: trusty
-
-compiler:
-    - gcc
-
-os:
-    - linux
+language: c
+compiler: gcc
+os: linux
 
 before_script:
-    ./autogen.sh
-
-language: c
+    - ./autogen.sh
 
 addons:
     apt:
         sources:
             - ubuntu-toolchain-r-test
         packages:
+            - libsystemd-journal-dev
             - valgrind
             - autoconf
             - automake
+            - libjson-c-dev
 
 script:
     - ./configure && make && make distcheck

Makefile.am

@@ -1,26 +1,42 @@
 
-AM_CFLAGS = -g $(LIBSYSTEMD_CFLAGS) $(LIBSYSTEMD_JOURNAL_CFLAGS) -Wall -Wno-uninitialized -W -D_FORTIFY_SOURCE=2
+AM_CFLAGS = -g \
+	$(JSON_C_CFLAGS) $(PCRE_CFLAGS) $(LIBSYSTEMD_CFLAGS) \
+	-Wall -Wno-uninitialized -W -D_FORTIFY_SOURCE=2
+
+AM_CPPFLAGS = \
+	-DDATADIR='"$(datadir)"' -DSYSCONFDIR='"$(sysconfdir)"'
 
 systemdsystemunitdir = @SYSTEMD_SYSTEMUNITDIR@
-systemdsystemunit_DATA = tallow.service
+systemdsystemunit_DATA = data/tallow.service
 
 sbin_PROGRAMS = tallow
-tallow_SOURCES = tallow.c
-tallow_LDADD = $(LIBSYSTEMD_LIBS) $(LIBSYSTEMD_JOURNAL_LIBS)
+tallow_SOURCES = \
+	src/tallow.c \
+	src/json.c \
+	src/json.h \
+	src/data.c \
+	src/data.h
+tallow_LDADD = $(JSON_C_LIBS) $(PCRE_LIBS) $(LIBSYSTEMD_LIBS)
 
-EXTRA_DIST = AUTHORS COPYING INSTALL tallow.service.in tallow.1.md
+pkgdata_DATA = data/sshd.json
 
-dist_man_MANS = tallow.1 tallow.conf.5
+EXTRA_DIST = \
+	AUTHORS COPYING INSTALL README.md \
+	data/tallow.service.in \
+	data/sshd.json \
+	man/tallow.conf.5.md \
+	man/tallow.1.md
+
+dist_man_MANS = man/tallow.1 man/tallow.conf.5
 
 dist_doc_DATA = tallow.conf
 
 DISTCHECK_CONFIGURE_FLAGS = \
 	--with-systemdsystemunitdir=$(DESTDIR)$(SYSTEMDSYSTEMUNITDIR)
 
-docs: tallow.1 tallow.conf.5
-tallow.conf.5:
-	ronn -r tallow.conf.5.md --pipe > tallow.conf.5
-
-tallow.1:
-	ronn -r tallow.1.md --pipe > tallow.1
+docs: $(dist_man_MANS)
+man/%.5: man/%.5.md
+	ronn -r $< --pipe > $@
 
+man/%.1: man/%.1.md
+	ronn -r $< --pipe > $@

README.md

@@ -16,7 +16,9 @@ Tallow attaches to the journal and subscribes to messages from
 /usr/sbin/sshd. The messages are matched against rules and the IP
 address is extracted from the message.  For each IP address that is
 extracted, the last timestamp and count is kept. Once the count exceeds
-a threshold, iptables is executed to set a IP-based blocking rule.
+a threshold, the offending IP address is added to an ipset and blocked 
+with a corresponding firewall rule. It will use firewalld or 
+iptables / ip6tables.
 
 The timestamp is kept for pruning. Records are pruned from the list
 if the IP address hasn't been seen by tallow for longer than the
@@ -66,4 +68,4 @@ tallow.
 
 Be very careful if you deploy tallow on systems that expect valid
 users to log on from many random source addresses. If your user
-mistypes their username, they could find themselves denied access.
+mistypes their username, they could find themselves denied access.

configure.ac

@@ -2,15 +2,18 @@
 # Process this file with autoconf to produce a configure script.
 
 AC_PREREQ([2.64])
-AC_INIT([tallow], [4], [auke-jan.h.kok@intel.com])
-AM_INIT_AUTOMAKE([])
+AC_INIT([tallow], [18], [auke-jan.h.kok@intel.com])
+AM_INIT_AUTOMAKE([foreign -Wall -Werror -Wno-portability silent-rules subdir-objects color-tests
+	no-dist-gzip dist-xz])
 AC_CONFIG_FILES([Makefile])
 
 # Checks for programs.
 AC_PROG_CC
 AC_PROG_INSTALL
 
-PKG_CHECK_MODULES(LIBSYSTEMD, libsystemd,, [PKG_CHECK_MODULES(LIBSYSTEMD_JOURNAL, libsystemd-journal)])
+PKG_CHECK_MODULES(PCRE, libpcre)
+PKG_CHECK_MODULES(JSON_C, json-c)
+PKG_CHECK_MODULES(LIBSYSTEMD, libsystemd,, [PKG_CHECK_MODULES(LIBSYSTEMD, libsystemd-journal)])
 AC_SUBST(LIBSYSTEMD_CFLAGS)
 AC_SUBST(LIBSYSTEMD_LIBS)
 AC_SUBST(LIBSYSTEMD_JOURNAL_CFLAGS)
@@ -27,5 +30,5 @@ fi
 AC_CHECK_HEADERS([stdlib.h stdio.h string.h stdarg.h limits.h sys/time.h])
 
 AC_OUTPUT([
-tallow.service
+data/tallow.service
 ])

data/dovecot.json

@@ -0,0 +1,12 @@
+[
+  {
+    "filter": "SYSLOG_IDENTIFIER=auth",
+    "items": [
+      {
+        "ban": 50,
+        "score": 0.6,
+        "pattern": "MESSAGE=pam_unix[(]dovecot:auth[)]: authentication failure; logname= uid=0 euid=0 tty=dovecot ruser=.*@.* rhost=([0-9a-z:.]+)"
+      }
+    ]
+  }
+]

data/sshd.json

@@ -0,0 +1,57 @@
+[
+  {
+    "filter": "SYSLOG_IDENTIFIER=sshd",
+    "items": [
+      {
+        "ban": 0,
+        "score": 0.2,
+        "pattern": "MESSAGE=Failed .* for .* from ([0-9a-z:.]+) port \\d+ ssh2"
+      },
+      {
+        "ban": 0,
+        "score": 0.2,
+        "pattern": "MESSAGE=error: PAM: Authentication failure for .* from ([0-9a-z:.]+)"
+      },
+      {
+        "ban": 10,
+        "score": 0.2,
+        "pattern": "MESSAGE=Invalid user .* from ([0-9a-z:.]+) port \\d+"
+      },
+      {
+        "ban": 10,
+        "score": 0.3,
+        "pattern": "MESSAGE=Did not receive identification string from ([0-9a-z:.]+) port \\d+"
+      },
+      {
+        "ban": 15,
+        "score": 0.4,
+        "pattern": "MESSAGE=Bad protocol version identification .* from ([0-9a-z:.]+)"
+      },
+      {
+        "ban": 15,
+        "score": 0.4,
+        "pattern": "MESSAGE=Connection closed by authenticating user .* ([0-9a-z:.]+) port \\d+"
+      },
+      {
+        "ban": 10,
+        "score": 0.3,
+        "pattern": "MESSAGE=Received disconnect from ([0-9a-z:.]+) port .*\\[preauth\\]"
+      },
+      {
+        "ban": 10,
+        "score": 0.3,
+        "pattern": "MESSAGE=Connection closed by ([0-9a-z:.]+) port .*\\[preauth\\]"
+      },
+      {
+        "ban": 30,
+        "score": 0.5,
+        "pattern": "MESSAGE=Failed .* for root from ([0-9a-z:.]+) port \\d+ ssh2"
+      },
+      {
+        "ban": 60,
+        "score": 0.6,
+        "pattern": "MESSAGE=Unable to negotiate with ([0-9a-z:.]+) port \\d+: no matching key exchange method found."
+      }
+    ]
+  }
+]

data/tallow.service.in

@@ -6,6 +6,7 @@ Description=Tallow Service
 ExecStart=@prefix@/sbin/tallow
 Restart=always
 RestartSec=3
+Nice=10
 
 [Install]
 WantedBy=network.target

man/tallow.1

@@ -0,0 +1,40 @@
+.\" generated with Ronn/v0.7.3
+.\" http://github.com/rtomayko/ronn/tree/0.7.3
+.
+.TH "TALLOW" "1" "October 2018" "" ""
+.
+.SH "NAME"
+\fBtallow\fR
+.
+.SH "tallow"
+Reduce log clutter due to ssh login attempts\.
+.
+.SH "SYNOPSIS"
+\fB/usr/sbin/tallow\fR
+.
+.SH "DESCRIPTION"
+\fBtallow\fR is a daemon that watches the systemd journal for messages from the \fBsshd\fR service\. It parses the messages and looks for attempted random logins such as failed logins to the root account and failed logins to invalid user accounts, and various other obviously malicious login attempts that try things as forcing old protocols, or weak key systems\.
+.
+.P
+If such logins were detected, the offending IP address is stored in a list\. Items from this list are regularly purged, but if the amount of times that a specific IP address is seen exceeds a threshold, an ipset(1) entry is inserted in the \fBtallow\fR or \fBtallow6\fR ipset, and further packets from that ip address will be blocked by an \fBiptables(1)\fR or \fBip6tables(1)\fR rule that tallow creates at startup\. Additionally, certain types of login failure will trigger a short term ban of further packets from the offending IP address immediately\.
+.
+.P
+The system administrator needs to assure that the tallow and tallow6 ipsets are left alone and that the inserted iptables rules are properly matching on packets\.
+.
+.P
+Care should be taken to assure that legitimate users are not blocked inadvertently\. You may wish to list any valid IP address with the whitelist option in tallow\.conf(5)\. Multiple addresses can be whitelisted\.
+.
+.SH "OPTIONS"
+The \fBtallow\fR daemon itself has no runtime configuration\. All configuration is done through the tallow\.conf(5) config file\.
+.
+.SH "SIGNALS"
+The \fBUSR1\fR signal causes \fBtallow\fR to print out it\'s internal tracking table of IP addresses\. This requires that tallow is compiled with the \fB\-DDEBUG=1\fR symbol passed to the compiler\.
+.
+.SH "SEE ALSO"
+systemd\-journald(1), iptables(1), ipset(1), tallow\.conf(5)
+.
+.SH "BUGS"
+\fBtallow\fR is \fBNOT A SECURITY SOLUTION\fR, nor does it protect against random password logins\. A attacker may still be able to logon to your systems if you allow password logins\.
+.
+.SH "AUTHOR"
+Auke Kok \fIauke\-jan\.h\.kok@intel\.com\fR

man/tallow.1.md

@@ -0,0 +1,61 @@
+
+## tallow 
+
+Reduce log clutter due to ssh login attempts.
+
+## SYNOPSIS
+
+`/usr/sbin/tallow`
+
+## DESCRIPTION
+
+`tallow` is a daemon that watches the systemd journal for messages
+from the `sshd` service. It parses the messages and looks for
+attempted random logins such as failed logins to the root account and
+failed logins to invalid user accounts, and various other obviously
+malicious login attempts that try things as forcing old protocols,
+or weak key systems.
+
+If such logins were detected, the offending IP address is stored in
+a list. Items from this list are regularly purged, but if the amount
+of times that a specific IP address is seen exceeds a threshold,
+an ipset(1) entry is inserted in the `tallow` or `tallow6`
+ipset, and further packets from that ip address will be blocked
+by an `iptables(1)` or `ip6tables(1)` rule that tallow creates at
+startup. Additionally, certain types of login failure will trigger
+a short term ban of further packets from the offending IP address
+immediately.
+
+The system administrator needs to assure that the tallow and tallow6
+ipsets are left alone and that the inserted iptables rules are properly
+matching on packets.
+
+Care should be taken to assure that legitimate users are not
+blocked inadvertently. You may wish to list any valid IP address
+with the whitelist option in tallow.conf(5). Multiple addresses can
+be whitelisted.
+
+## OPTIONS
+
+The `tallow` daemon itself has no runtime configuration. All
+configuration is done through the tallow.conf(5) config file.
+
+## SIGNALS
+
+The `USR1` signal causes `tallow` to print out it's internal tracking
+table of IP addresses. This requires that tallow is compiled with
+the `-DDEBUG=1` symbol passed to the compiler.
+
+## SEE ALSO
+
+systemd-journald(1), iptables(1), ipset(1), tallow.conf(5)
+
+## BUGS
+
+`tallow` is `NOT A SECURITY SOLUTION`, nor does it protect against
+random password logins. A attacker may still be able to logon to your
+systems if you allow password logins.
+
+## AUTHOR
+
+Auke Kok <auke-jan.h.kok@intel.com>

man/tallow.conf.5

@@ -0,0 +1,77 @@
+.\" generated with Ronn/v0.7.3
+.\" http://github.com/rtomayko/ronn/tree/0.7.3
+.
+.TH "TALLOW" "5" "October 2019" "" ""
+.
+.SH "NAME"
+\fBtallow\fR
+.
+.SH "tallow\.conf"
+The tallow configuration file
+.
+.SH "NAME"
+tallow\.conf \- Tallow daemon configuration file
+.
+.SH "SYNOPSIS"
+\fB/etc/tallow\.conf\fR
+.
+.SH "DESCRIPTION"
+This file is read on startup by the tallow(1) daemon, and can be used to provide options to the tallow daemon\. If not present, tallow will operate with built\-in defaults\.
+.
+.SH "OPTIONS"
+\fBipt_path\fR=\fB<string>\fR Specifies the location of the ipset(1) program and iptables(1), ip6tables(1), or firewall\-cmd(1) programs\. By default, tallow will look in "/usr/sbin" for them\.
+.
+.P
+\fBexpires\fR=\fB<int>\fR The number of seconds that IP addresses are blocked for\. Note that due to the implementation, IP addresses may be blocked for much longer than this period\. If IP addresses are seen, but not blocked within this period, they are also removed from the watch list\. Defaults to 3600s\.
+.
+.P
+\fBwhitelist\fR=\fB<ip address|pattern>\fR Specify an IP address or \fBpattern\fR that should never be blocked\. Multiple IP addresses can be included by repeating the \fBwhitelist\fR option several times\. By default, 127\.0\.0\.1, 192\.168\., and 10\. are whitelisted\. If you create a manual whitelist, you must include these entries if you want to continue them to be whitelisted as well, otherwise they will be omitted from the whitelist\.
+.
+.P
+If the last character of the listed ip adress is a \fB\.\fR or a \fB:\fR, then the matching is only performed on the leftmost characters of an IP address against the whitelist entry\. For instance, if you whitelist \fB10\.\fR then all IP addresses in the \fB10/8\fR subnet mask will match this whitelist entry and never be blocked\.
+.
+.P
+\fBipv6\fR=\fB<0|1>\fR Enable or disable ipv6 (ip6tables) support\. Ipv6 is disabled automatically on systems that do not appear to have ipv6 support and enabled when ipv6 is present\. Use this option to explicitly disable ipv6 support if your system does not have ipv6 or is missing ip6tables\. Even with ipv6 disabled, tallow will track and log ipv6 addresses\.
+.
+.P
+\fBnocreate\fR=\fB<0|1>\fR Disable the creation of firewall rules and ipset sets\. By default, tallow will create new firewall\-cmd(1) or iptables(1) and ip6tables(1) rules when needed automatically\. If set to \fB1\fR, \fBtallow(1)\fR will not create any new firewall DROP rules or ipset sets that are needed work\. You should create them manually before tallow starts up and remove them afterwards using the sets of commands below\.
+.
+.P
+Use the following commands if you\'re using iptables(1):
+.
+.IP "" 4
+.
+.nf
+
+  ipset create tallow hash:ip family inet timeout 3600
+  iptables \-t filter \-I INPUT 1 \-m set \-\-match\-set tallow src \-j DROP
+
+  ipset create tallow6 hash:ip family inet6 timeout 3600
+  ip6tables \-t filter \-I INPUT 1 \-m set \-\-match\-set tallow6 src \-j DROP
+.
+.fi
+.
+.IP "" 0
+.
+.P
+Use the following commands if you\'re using firewalld(1):
+.
+.IP "" 4
+.
+.nf
+
+  firewall\-cmd \-\-permanent \-\-new\-ipset=tallow \-\-type=hash:ip \-\-family=inet \-\-option=timeout=3600
+  firewall\-cmd \-\-permanent \-\-direct \-\-add\-rule ipv4 filter INPUT 1 \-m set \-\-match\-set tallow src \-j DROP
+
+  firewall\-cmd \-\-permanent \-\-new\-ipset=tallow6 \-\-type=hash:ip \-\-family=inet6 \-\-option=timeout=3600
+  firewall\-cmd \-\-permanent \-\-direct \-\-add\-rule ipv6 filter INPUT 1 \-m set \-\-match\-set tallow6 src \-j DROP
+.
+.fi
+.
+.IP "" 0
+.
+.SH "SEE ALSO"
+tallow(1)
+.
+.SH "AUTHOR"
+Auke Kok \fIauke\-jan\.h\.kok@intel\.com\fR

man/tallow.conf.5.md

@@ -0,0 +1,90 @@
+
+## tallow.conf
+
+The tallow configuration file
+
+## NAME
+
+tallow.conf - Tallow daemon configuration file
+
+## SYNOPSIS
+
+`/etc/tallow.conf`
+
+## DESCRIPTION
+
+This file is read on startup by the tallow(1) daemon, and can
+be used to provide options to the tallow daemon. If not present,
+tallow will operate with built-in defaults.
+
+## OPTIONS
+
+`ipt_path`=`<string>`
+Specifies the location of the ipset(1) program and iptables(1), 
+ip6tables(1), or firewall-cmd(1) programs. By default, tallow will 
+look in "/usr/sbin" for them.
+
+`expires`=`<int>`
+The number of seconds that IP addresses are blocked for. Note that
+due to the implementation, IP addresses may be blocked for much
+longer than this period. If IP addresses are seen, but not
+blocked within this period, they are also removed from the
+watch list. Defaults to 3600s.
+
+`whitelist`=`<ip address|pattern>`
+Specify an IP address or `pattern` that should never be
+blocked. Multiple IP addresses can be included by repeating the
+`whitelist` option several times. By default, 127.0.0.1, 192.168., and
+10. are whitelisted. If you create a manual whitelist, you must include
+these entries if you want to continue them to be whitelisted as
+well, otherwise they will be omitted from the whitelist.
+
+If the last character of the listed ip adress is a `.` or a `:`, then
+the matching is only performed on the leftmost characters of an IP
+address against the whitelist entry. For instance, if you whitelist
+`10.` then all IP addresses in the `10/8` subnet mask will match this
+whitelist entry and never be blocked.
+
+`ipv6`=`<0|1>`
+Enable or disable ipv6 (ip6tables) support. Ipv6 is disabled
+automatically on systems that do not appear to have ipv6 support
+and enabled when ipv6 is present. Use this option to explicitly
+disable ipv6 support if your system does not have ipv6 or is
+missing ip6tables. Even with ipv6 disabled, tallow will track
+and log ipv6 addresses.
+
+`nocreate`=`<0|1>` Disable the creation of firewall rules and ipset sets. By
+default, tallow will create new firewall-cmd(1) or iptables(1) and ip6tables(1)
+rules when needed automatically. If set to `1`, `tallow(1)` will not create any
+new firewall DROP rules or ipset sets that are needed work. You should create
+them manually before tallow starts up and remove them afterwards using the sets
+of commands below. 
+
+Use the following commands if you're using iptables(1):
+
+  ```
+  ipset create tallow hash:ip family inet timeout 3600
+  iptables -t filter -I INPUT 1 -m set --match-set tallow src -j DROP
+
+  ipset create tallow6 hash:ip family inet6 timeout 3600
+  ip6tables -t filter -I INPUT 1 -m set --match-set tallow6 src -j DROP
+  ```
+
+Use the following commands if you're using firewalld(1):
+
+```
+  firewall-cmd --permanent --new-ipset=tallow --type=hash:ip --family=inet --option=timeout=3600
+  firewall-cmd --permanent --direct --add-rule ipv4 filter INPUT 1 -m set --match-set tallow src -j DROP
+  
+  firewall-cmd --permanent --new-ipset=tallow6 --type=hash:ip --family=inet6 --option=timeout=3600
+  firewall-cmd --permanent --direct --add-rule ipv6 filter INPUT 1 -m set --match-set tallow6 src -j DROP
+  
+  ```
+
+## SEE ALSO
+
+tallow(1)
+
+## AUTHOR
+
+Auke Kok <auke-jan.h.kok@intel.com>

src/data.c

@@ -0,0 +1,175 @@
+/*
+ * data.h - IP block sshd login abuse
+ *
+ * (C) Copyright 2019 Intel Corporation
+ * Authors:
+ *     Auke Kok <auke-jan.h.kok@intel.com>
+ *
+ * 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; version 3
+ * of the License.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <sys/time.h>
+#include <malloc.h>
+
+#include <pcre.h>
+
+#include "data.h"
+
+struct block_struct *blocks;
+struct pattern_struct *patterns;
+struct filter_struct *filters;
+struct whitelist_struct *whitelist;
+
+void filter_add(const char *filter)
+{
+	struct filter_struct *h = filters;
+
+	/* filter duplicates */
+	while (h) {
+		if (strcmp(h->filter, filter) == 0)
+			return;
+
+		h = h->next;
+	}
+
+	struct filter_struct *f = calloc(1, sizeof(struct filter_struct));
+	if (!f) {
+		perror("calloc()");
+		exit(EXIT_FAILURE);
+	}
+
+	f->filter = strdup(filter);
+
+	h = filters;
+	if (!h) {
+		filters = f;
+	} else {
+		while (h->next)
+			h = h->next;
+		h->next = f;
+	}
+}
+
+void pattern_add(const char *pattern, int ban, double score)
+{
+	struct pattern_struct *p = calloc(1, sizeof(struct pattern_struct));
+	if (!p) {
+		perror("calloc()");
+		exit(EXIT_FAILURE);
+	}
+
+	p->pattern = strdup(pattern);
+	p->instant_block = ban;
+	p->weight = score;
+
+	const char *pcre_err;
+	int err;
+	p->re = pcre_compile(pattern, 0, &pcre_err, &err, NULL);
+	if (!p->re) {
+		fprintf(stderr, "PCRE compilation failed. Offset %d: %s\n",
+			err, pcre_err);
+		exit(EXIT_FAILURE);
+	}
+
+	struct pattern_struct *h = patterns;
+	if (!h) {
+		patterns = p;
+	} else {
+		while (h->next)
+			h = h->next;
+		h->next = p;
+	}
+}
+
+void whitelist_add(const char *ip)
+{
+	struct whitelist_struct *w = calloc(1, sizeof(struct whitelist_struct));
+
+	if (!w) {
+		perror("calloc()");
+		exit(EXIT_FAILURE);
+	}
+
+	w->ip = strdup(ip);
+
+	size_t l = strlen(ip);
+	if ((ip[l-1] == '.') || (ip[l-1] == ':'))
+		w->len = l;
+	else
+		w->len = -1;
+
+	struct whitelist_struct *h = whitelist;
+	if (!h) {
+		whitelist = w;
+	} else {
+		while (h->next)
+			h = h->next;
+		h->next = w;
+	}
+}
+
+bool whitelist_find(const char *ip)
+{
+	struct whitelist_struct *w = whitelist;
+	while (w) {
+		if (w->len > 0) {
+			if (!strncmp(w->ip, ip, w->len))
+				return (true);
+		} else {
+			if (!strcmp(w->ip, ip))
+				return (true);
+		}
+		w = w->next;
+	}
+
+	return (false);
+}
+
+void prune(int expires)
+{
+	struct block_struct *s = blocks;
+	struct block_struct *p;
+	struct timeval tv;
+
+	(void) gettimeofday(&tv, NULL);
+	p = NULL;
+
+	while (s) {
+		/*
+		 * Expire all records, but if they are blocked, make sure to
+		 * expire them *before* the ipset rule expires, otherwise
+		 * you might get an IP to bypass checks.
+		 */
+		time_t age = tv.tv_sec - s->time.tv_sec;
+		if ((age > expires) ||
+		    ((s->blocked) && (age > expires / 2))) {
+			dbg("Expired record for %s\n", s->ip);
+			if (p) {
+				p->next = s->next;
+				free(s->ip);
+				free(s);
+				s = p->next;
+				continue;
+			} else {
+				blocks = s->next;
+				free(s->ip);
+				free(s);
+				s = blocks;
+				p = NULL;
+				continue;
+			}
+		}
+		p = s;
+		s = s->next;
+	}
+
+	/* return some memory */
+	malloc_trim(0);
+}

src/data.h

@@ -0,0 +1,60 @@
+/*
+ * data.h - IP block sshd login abuse
+ *
+ * (C) Copyright 2019 Intel Corporation
+ * Authors:
+ *     Auke Kok <auke-jan.h.kok@intel.com>
+ *
+ * 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; version 3
+ * of the License.
+ */
+
+#pragma once
+
+#include <pcre.h>
+
+#ifdef DEBUG
+#define dbg(args...) fprintf(stderr, ##args)
+#else
+#define dbg(args...) do {} while (0)
+#endif
+
+struct block_struct {
+	char *ip;
+	float score;
+	struct timeval time;
+	struct block_struct *next;
+	bool blocked;
+};
+
+struct whitelist_struct {
+	char *ip;
+	size_t len;
+	struct whitelist_struct *next;
+};
+
+struct pattern_struct {
+	int instant_block;
+	float weight;
+	char *pattern;
+	pcre *re;
+	struct pattern_struct *next;
+};
+
+struct filter_struct {
+	char *filter;
+	struct filter_struct *next;
+};
+
+extern struct block_struct *blocks;
+extern struct pattern_struct *patterns;
+extern struct filter_struct *filters;
+extern struct whitelist_struct *whitelist;
+
+void filter_add(const char *filter);
+void pattern_add(const char *pattern, int ban, double score);
+void whitelist_add(const char *ip);
+bool whitelist_find(const char *ip);
+void prune(int expires);

src/json.c

@@ -0,0 +1,218 @@
+/*
+ * json.c - IP block sshd login abuse
+ *
+ * (C) Copyright 2019 Intel Corporation
+ * Authors:
+ *     Auke Kok <auke-jan.h.kok@intel.com>
+ *
+ * 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; version 3
+ * of the License.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <dirent.h>
+#include <fcntl.h>
+
+#include <json-c/json.h>
+
+#include "data.h"
+
+static const char *s_pattern;
+static const char *s_filter;
+static int s_ban;
+static double s_score;
+static bool g_filter, g_ban, g_score, g_pattern = false;
+
+static int json_parse(json_object *ob)
+{
+	int i, count = 0;
+	bool l_filter, l_ban, l_score, l_pattern = false;
+
+	json_object_object_foreach(ob, key, val) {
+		enum json_type type;
+		type = json_object_get_type(val);
+		switch (type) {
+		case json_type_null:
+			break;
+		case json_type_boolean:
+			break;
+		case json_type_double:
+			if (strcmp(key, "score") == 0) {
+				l_score = g_score = true;
+				s_score = json_object_get_double(val);
+			} else {
+				fprintf(stderr, "Invalid JSON key \"%s\"\n", key);
+				return (0);
+			}
+			break;
+		case json_type_int:
+			if (strcmp(key, "ban") == 0) {
+				l_ban = g_ban = true;
+				s_ban = json_object_get_int(val);
+			} else {
+				fprintf(stderr, "Invalid JSON key \"%s\"\n", key);
+				return (0);
+			}
+			break;
+		case json_type_string:
+			if (strcmp(key, "filter") == 0) {
+				l_filter = g_filter = true;
+				s_filter = json_object_get_string(val);
+			} else if (strcmp(key, "pattern") == 0) {
+				l_pattern = g_pattern = true;
+				s_pattern = json_object_get_string(val);
+			} else {
+				fprintf(stderr, "Invalid JSON key \"%s\"\n", key);
+				return (0);
+			}
+			break;
+		case json_type_array:
+			ob = json_object_object_get(ob, key);
+			int len = json_object_array_length(ob);
+			json_object *val;
+			for (i = 0; i < len; i++) {
+				val = json_object_array_get_idx(ob, i);
+				count += json_parse(val);
+			}
+			break;
+		case json_type_object:
+			ob = json_object_object_get(ob, key);
+			count += json_parse(ob);
+			break;
+		}
+	}
+
+	/* check and finish if can */
+	if (g_score && g_ban && g_pattern && g_filter) {
+#ifdef DEBUG
+		fprintf(stderr, "Adding: %s %s %d %lf\n", s_filter, s_pattern, s_ban, s_score);
+#endif
+		filter_add(s_filter);
+		pattern_add(s_pattern, s_ban, s_score);
+		count++;
+	}
+
+	/* cleanup */
+	if (l_score) {
+		l_score = g_score = false;
+	} else if (l_ban) {
+		l_ban = g_ban = false;
+	} else if (l_pattern) {
+		l_pattern = g_pattern = false;
+	} else if (l_filter) {
+		l_filter = g_filter = false;
+	}
+
+	return (count);
+}
+
+static int json_load_file(const char* file)
+{
+	int i, count = 0;
+	char *json;
+	int fd;
+	struct stat st;
+	fd = open(file, O_RDONLY);
+	fstat(fd, &st);
+	json = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	close(fd);
+
+	struct json_object *obj;
+
+	obj = json_tokener_parse(json);
+	if (json_object_is_type(obj,json_type_array)) {
+		int len = json_object_array_length(obj);
+		json_object *val;
+		for (i = 0; i < len; i++) {
+			val = json_object_array_get_idx(obj, i);
+			count += json_parse(val);
+		}
+	} else if (json_object_is_type(obj, json_type_object)) {
+		count += json_parse(obj);
+	} else {
+		fprintf(stderr, "This does not look like JSON: %s\n", file);
+		return (0);
+	}
+
+	json_object_put(obj);
+
+	munmap(json, st.st_size);
+	return (count);
+}
+
+static int json_load_dir(const char *dir)
+{
+	int count = 0;
+
+	DIR *d = opendir(dir);
+	if (!d) {
+		fprintf(stderr, "Skipped reading %s: %s\n", dir, strerror(errno));
+		return (count);
+	}
+	struct dirent *entry;
+	for (;;) {
+		entry = readdir(d);
+		if (!entry)
+			break;
+		size_t l = strlen(entry->d_name);
+		if (l < strlen(".json"))
+			continue;
+		if (strcmp(entry->d_name + l - strlen(".json"), ".json") == 0) {
+			char *p;
+			if (!asprintf(&p, "%s/%s", dir, entry->d_name)) {
+				fprintf(stderr, "asprintf: %s\n", strerror(errno));
+				exit(EXIT_FAILURE);
+			}
+
+			/* allow /etc/tallow files to override /usr/share/tallow files */
+			if (strcmp(dir, DATADIR "/" PACKAGE_NAME) == 0) {
+				char *sp;
+				if (!asprintf(&sp, SYSCONFDIR "/" PACKAGE_NAME "/%s", entry->d_name)) {
+					fprintf(stderr, "asprintf: %s\n", strerror(errno));
+					exit(EXIT_FAILURE);
+				}
+
+				struct stat st;
+				if (stat(sp, &st) == 0) {
+					dbg("Skipped " SYSCONFDIR "/" PACKAGE_NAME "/%s\n", entry->d_name);
+					free(sp);
+					continue;
+				}
+				free(sp);
+			}
+
+			int c = json_load_file(p);
+			fprintf(stderr, "%s: %d patterns\n", p, c);
+			count += c;
+			free(p);
+		}
+
+	}
+	closedir(d);
+
+	return (count);
+}
+
+void json_load_patterns(void)
+{
+	int count = 0;
+	count += json_load_dir(DATADIR "/" PACKAGE_NAME);
+	count += json_load_dir(SYSCONFDIR "/" PACKAGE_NAME);
+	fprintf(stderr, "Loaded %d patterns total\n", count);
+	if (count < 1) {
+		/* consider sending a special exit code here */
+		fprintf(stderr, "No patterns loaded, nothing to do!\n");
+		exit(EXIT_SUCCESS);
+	}
+}

src/json.h

@@ -0,0 +1,16 @@
+/*
+ * json.h - IP block sshd login abuse
+ *
+ * (C) Copyright 2019 Intel Corporation
+ * Authors:
+ *     Auke Kok <auke-jan.h.kok@intel.com>
+ *
+ * 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; version 3
+ * of the License.
+ */
+
+#pragma once
+
+void json_load_patterns(void);

src/tallow.c

@@ -0,0 +1,441 @@
+/*
+ * tallow.c - IP block sshd login abuse
+ *
+ * (C) Copyright 2015-2019 Intel Corporation
+ * Authors:
+ *     Auke Kok <auke-jan.h.kok@intel.com>
+ *
+ * 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; version 3
+ * of the License.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <signal.h>
+#include <unistd.h>
+#include <limits.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <linux/limits.h>
+
+#include <pcre.h>
+#include <systemd/sd-journal.h>
+
+#include "json.h"
+#include "data.h"
+
+#define MAX_OFFSETS 30
+
+static char ipt_path[PATH_MAX];
+static int expires = 3600;
+static int has_ipv6 = 0;
+static bool nocreate = false;
+static sd_journal *j;
+
+static int ext(char *fmt, ...)
+{
+	va_list args;
+	char cmd[1024];
+	int ret = 0;
+
+	va_start(args, fmt);
+	vsnprintf(cmd, sizeof(cmd), fmt, args);
+	va_end(args);
+
+	ret = system(cmd);
+	if (ret)
+		fprintf(stderr, "Error executing \"%s\": returned %d\n", cmd, ret);
+	return (ret);
+}
+
+static void ext_ignore(char *fmt, ...)
+{
+	va_list args;
+	char cmd[1024];
+
+	va_start(args, fmt);
+	vsnprintf(cmd, sizeof(cmd), fmt, args);
+	va_end(args);
+
+	__attribute__((unused)) int ret = system(cmd);
+}
+
+static void reset_rules(void)
+{
+	/* reset all rules in case the running fw changes */
+	ext_ignore("%s/firewall-cmd --permanent --direct --remove-rule ipv4 filter INPUT 1 -m set --match-set tallow src -j DROP 2> /dev/null", ipt_path);
+	ext_ignore("%s/firewall-cmd --permanent --delete-ipset=tallow 2> /dev/null", ipt_path);
+
+	/* delete iptables ref to set before the ipset! */
+	ext_ignore("%s/iptables -t filter -D INPUT -m set --match-set tallow src -j DROP 2> /dev/null", ipt_path);
+	ext_ignore("%s/ipset destroy tallow 2> /dev/null", ipt_path);
+
+	if (has_ipv6) {
+		ext_ignore("%s/firewall-cmd --permanent --direct --remove-rule ipv6 filter INPUT 1 -m set --match-set tallow6 src -j DROP 2> /dev/null", ipt_path);
+		ext_ignore("%s/firewall-cmd --permanent --delete-ipset=tallow6 2> /dev/null", ipt_path);
+		
+		/* delete iptables ref to set before the ipset! */
+		ext_ignore("%s/ip6tables -t filter -D INPUT -m set --match-set tallow6 src -j DROP 2> /dev/null", ipt_path);
+		ext_ignore("%s/ipset destroy tallow6 2> /dev/null", ipt_path);
+	}
+}
+
+static void setup(void)
+{
+	static bool done = false;
+	if (done)
+		return;
+	done = true;
+
+	if (nocreate)
+		return;
+
+	/* firewalld */
+	char *fwd_path;
+	if (asprintf(&fwd_path, "%s/firewall-cmd", ipt_path) < 0) {
+		exit(EXIT_FAILURE);
+	}
+
+	if ((access(fwd_path, X_OK) == 0) && ext("%s/firewall-cmd --state --quiet", ipt_path) == 0) {
+		fprintf(stdout, "firewalld is running and will be used by tallow.\n");
+
+		reset_rules();
+
+		/* create ipv4 rule and ipset */
+		if (ext("%s/firewall-cmd --permanent --quiet --new-ipset=tallow --type=hash:ip --family=inet --option=timeout=%d", ipt_path, expires)) {
+			fprintf(stderr, "Unable to create ipv4 ipset with firewall-cmd.\n");
+			exit(EXIT_FAILURE);
+		}
+		if (ext("%s/firewall-cmd --permanent --direct --quiet --add-rule ipv4 filter INPUT 1 -m set --match-set tallow src -j DROP", ipt_path)) {
+			fprintf(stderr, "Unable to create ipv4 firewalld rule.\n");
+			exit(EXIT_FAILURE);
+		}
+
+		/* create ipv6 rule and ipset */
+		if (has_ipv6) {
+			if (ext("%s/firewall-cmd --permanent --quiet --new-ipset=tallow6 --type=hash:ip --family=inet6 --option=timeout=%d", ipt_path, expires)) {
+				fprintf(stderr, "Unable to create ipv6 ipset with firewall-cmd.\n");
+				exit(EXIT_FAILURE);
+			}
+			if (ext("%s/firewall-cmd --permanent --direct --quiet --add-rule ipv6 filter INPUT 1 -m set --match-set tallow6 src -j DROP ", ipt_path)) {
+				fprintf(stderr, "Unable to create ipv6 firewalld rule.\n");
+				exit(EXIT_FAILURE);
+			}
+		}
+
+		/* reload firewalld for ipsets to load */
+		if (ext("%s/firewall-cmd --reload --quiet", ipt_path, expires)) {
+			fprintf(stderr, "Unable to reload firewalld rules.\n");
+			exit(EXIT_FAILURE);
+		}
+	} else {
+		/* iptables */
+		reset_rules();
+
+		/* create ipv4 rule and ipset */
+		if (ext("%s/ipset create tallow hash:ip family inet timeout %d", ipt_path, expires)) {
+			fprintf(stderr, "Unable to create ipv4 ipset.\n");
+			exit(EXIT_FAILURE);
+		}
+		if (ext("%s/iptables -t filter -A INPUT -m set --match-set tallow src -j DROP", ipt_path)) {
+			fprintf(stderr, "Unable to create iptables rule.\n");
+			exit(EXIT_FAILURE);
+		}
+
+		/* create ipv6 rule and ipset */
+		if (has_ipv6) {
+			if (ext("%s/ipset create tallow6 hash:ip family inet6 timeout %d", ipt_path, expires)) {
+				fprintf(stderr, "Unable to create ipv6 ipset.\n");
+				exit(EXIT_FAILURE);
+			}
+			if (ext("%s/ip6tables -t filter -A INPUT -m set --match-set tallow6 src -j DROP", ipt_path)) {
+				fprintf(stderr, "Unable to create ipt6ables rule.\n");
+				exit(EXIT_FAILURE);
+			}
+		}
+	}
+
+	free(fwd_path);
+}
+
+static void block(struct block_struct *s, int instant_block)
+{
+	setup();
+
+	if (strchr(s->ip, ':')) {
+		if (has_ipv6) {
+			if (instant_block > 0) {
+				(void) ext("%s/ipset -! add tallow6 %s timeout %d",
+					   ipt_path, s->ip, instant_block);
+			} else {
+				(void) ext("%s/ipset -! add tallow6 %s", ipt_path, s->ip);
+				s->blocked = true;
+			}
+		}
+	} else {
+		if (instant_block > 0) {
+			(void) ext("%s/ipset -! add tallow %s timeout %d",
+				   ipt_path, s->ip, instant_block);
+		} else {
+			(void) ext("%s/ipset -! add tallow %s", ipt_path, s->ip);
+			s->blocked = true;
+		}
+	}
+
+	if (s->blocked) {
+		fprintf(stderr, "Blocked %s\n", s->ip);
+	} else {
+		dbg("Throttled %s\n", s->ip);
+	}
+}
+
+void find(const char *ip, float weight, int instant_block)
+{
+	struct block_struct *s = blocks;
+	struct block_struct *n;
+
+	if (!ip)
+		return;
+
+	/*
+	 * not validating the IP address format here, just
+	 * making sure we're not passing special characters
+	 * to system().
+	 */
+	if (strspn(ip, "0123456789abcdef:.") != strlen(ip))
+		return;
+
+	if (whitelist_find(ip))
+		return;
+
+	/* walk and update entry */
+	while (s) {
+		if (!strcmp(s->ip, ip)) {
+			s->score += weight;
+			dbg("%s: %1.3f\n", s->ip, s->score);
+			(void) gettimeofday(&s->time, NULL);
+
+			if (s->blocked) {
+				return;
+			}
+
+			if (s->score >= 1.0) {
+				block(s, 0);
+			} else if (instant_block > 0) {
+				block(s, instant_block);
+			}
+
+			return;
+		}
+
+		if (s->next)
+			s = s->next;
+		else
+			break;
+	}
+
+	/* append */
+	n = calloc(1, sizeof(struct block_struct));
+	if (!n) {
+		fprintf(stderr, "Out of memory.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (!blocks)
+		blocks = n;
+	else
+		s->next = n;
+
+	n->ip = strdup(ip);
+	n->score = weight;
+	n->next = NULL;
+	n->blocked = false;
+	(void) gettimeofday(&n->time, NULL);
+	dbg("%s: %1.3f\n", n->ip, n->score);
+
+	if (weight >= 1.0) {
+		block(n, 0);
+	} else if (instant_block > 0) {
+		block(n, instant_block);
+	}
+	return;
+}
+
+#ifdef DEBUG
+static void sigusr1(int u __attribute__ ((unused)))
+{
+	fprintf(stderr, "Dumping score list on request:\n");
+	struct block_struct *s = blocks;
+	while (s) {
+		fprintf(stderr, "%ld %s %1.3f\n", s->time.tv_sec, s->ip, s->score);
+		s = s->next;
+	}
+}
+#endif
+
+
+int main(void)
+{
+	int r;
+	FILE *f;
+	int timeout = 60;
+	long long int last_timestamp = 0;
+
+	json_load_patterns();
+
+	strcpy(ipt_path, "/usr/sbin");
+
+#ifdef DEBUG
+	fprintf(stderr, "Debug output enabled. Send SIGUSR1 to dump internal state table\n");
+
+	struct sigaction s;
+
+	memset(&s, 0, sizeof(struct sigaction));
+	s.sa_handler = sigusr1;
+	sigaction(SIGUSR1, &s, NULL);
+#endif
+
+	if (access("/proc/sys/net/ipv6", R_OK | X_OK) == 0)
+		has_ipv6 = 1;
+
+	f = fopen(SYSCONFDIR "/tallow.conf", "r");
+	if (f) {
+		char buf[256];
+		char *key;
+		char *val;
+
+		while (fgets(buf, 80, f) != NULL) {
+			char *c;
+
+			c = strchr(buf, '\n');
+			if (c) *c = 0; /* remove trailing \n */
+
+			if (buf[0] == '#')
+				continue; /* comment line */
+
+			key = strtok(buf, "=");
+			if (!key)
+				continue;
+			val = strtok(NULL, "=");
+			if (!val)
+				continue;
+
+			// todo: filter leading/trailing whitespace
+			if (!strcmp(key, "ipt_path"))
+				strncpy(ipt_path, val, PATH_MAX - 1);
+			if (!strcmp(key, "expires"))
+				expires = atoi(val);
+			if (!strcmp(key, "whitelist"))
+				whitelist_add(val);
+			if (!strcmp(key, "ipv6"))
+				has_ipv6 = atoi(val);
+			if (!strcmp(key, "nocreate"))
+				nocreate = (atoi(val) == 1);
+		}
+		fclose(f);
+	}
+
+	if (!has_ipv6)
+		fprintf(stdout, "ipv6 support disabled.\n");
+
+	if (!whitelist) {
+		whitelist_add("127.0.0.1");
+		whitelist_add("192.168.");
+		whitelist_add("10.");
+	}
+
+	r = sd_journal_open(&j, SD_JOURNAL_LOCAL_ONLY);
+	if (r < 0) {
+		fprintf(stderr, "Failed to open journal: %s\n", strerror(-r));
+		exit(EXIT_FAILURE);
+	}
+
+	/* add all filters */
+	struct filter_struct *flt = filters;
+	while (flt) {
+		sd_journal_add_match(j, flt->filter, 0);
+		flt = flt->next;
+	}
+
+	/* go to the tail and wait */
+	r = sd_journal_seek_tail(j);
+	sd_journal_wait(j, (uint64_t) 0);
+	dbg("sd_journal_seek_tail() returned %d\n", r);
+	while (sd_journal_next(j) != 0)
+		r++;
+	dbg("Forwarded through %d items in the journal to reach the end\n", r);
+
+	fprintf(stderr, PACKAGE_STRING " Started\n");
+
+	for (;;) {
+		const void *d, *dt;
+		size_t l, dl;
+
+		r = sd_journal_wait(j, (uint64_t) timeout * 1000000);
+		if (r == SD_JOURNAL_INVALIDATE) {
+			fprintf(stderr, "Journal was rotated, resetting\n");
+			sd_journal_seek_tail(j);
+		} else if (r == SD_JOURNAL_NOP) {
+			dbg("Timeout reached, waiting again\n");
+			continue;
+		}
+
+		while (sd_journal_next(j) != 0) {
+			char *m;
+
+			/*
+			 * discard messages older than ones we've already seen before
+			 * this happens when the journal rotates - we get replayed events
+			 */
+			if (sd_journal_get_data(j, "_SOURCE_REALTIME_TIMESTAMP", &dt, &dl) == 0) {
+				long long int lt = atoi(dt + strlen("_SOURCE_REALTIME_TIMESTAMP="));
+				if (lt > last_timestamp)
+					last_timestamp = lt;
+				else if (lt < last_timestamp)
+					continue;
+			}
+
+			if (sd_journal_get_data(j, "MESSAGE", &d, &l) < 0) {
+				fprintf(stderr, "Failed to read message field: %s\n", strerror(-r));
+				break;
+			}
+
+			m = strndup(d, l+1);
+			m[l] = '\0';
+
+			struct pattern_struct *pat = patterns;
+			while (pat) {
+				int off[MAX_OFFSETS];
+				int ret = pcre_exec(pat->re, NULL, m, l, 0, 0, off, MAX_OFFSETS);
+				if (ret == 2) {
+					const char *s;
+					ret = pcre_get_substring(m, off, 2, 1, &s);
+					if (ret > 0) {
+						dbg("%s == %s\n", s, pat->pattern);
+						find(s, pat->weight, pat->instant_block);
+						pcre_free_substring(s);
+					}
+				}
+
+				pat = pat->next;
+			}
+
+			free(m);
+
+		}
+
+		prune(expires);
+	}
+
+	sd_journal_close(j);
+
+	exit(EXIT_SUCCESS);
+}

tallow.1.md

@@ -1,51 +0,0 @@
-
-## tallow 
-
-Reduce log clutter due to ssh login attempts.
-
-## SYNOPSIS
-
-`/usr/sbin/tallow`
-
-## DESCRIPTION
-
-`tallow` is a daemon that watches the systemd journal for
-messages from the `sshd` service. It parses the messages
-and looks for attempted random logins such as failed logins to the
-root account and failed logins to invalid user accounts.
-
-If such logins were detected, the offending IP address is stored
-in a list. Items from this list are regularly purged, but if
-the amount of times that a specific IP address is seen exceeds
-a threshold (default 3), an ipset(1) entry is inserted in the
-`tallow` or `tallow6` ipset, and further packets from that ip
-address will be blocked by an `iptables(1)` or `ip6tables(1)`
-rule that tallow creates at startup.
-
-The system administrator needs to assure that the tallow
-and tallow6 ipsets are left alone and that the inserted
-iptables rules are properly matching on packets.
-
-Care should be taken to assure that legitimate users are not
-blocked inadvertently. You may wish to list any valid IP address
-with the whitelist option in tallow.conf(5). Multiple addresses
-can be whitelisted.
-
-## OPTIONS
-
-The `tallow` daemon itself has no runtime configuration. All
-configuration is done through the tallow.conf(5) config file.
-
-## SEE ALSO
-
-systemd-journald(1), iptables(1), tallow.conf(5)
-
-## BUGS
-
-`tallow` is `NOT A SECURITY SOLUTION`, nor does it protect
-against random password logins. A attacker may still be able to
-logon to your systems if you allow password logins.
-
-## AUTHOR
-
-Auke Kok <auke-jan.h.kok@intel.com>

tallow.c

@@ -1,383 +0,0 @@
-/*
- * tallow.c - IP block sshd login abuse
- *
- * (C) Copyright 2015 Intel Corporation
- * Authors:
- *     Auke Kok <auke-jan.h.kok@intel.com>
- *
- * 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; version 3
- * of the License.
- */
-
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-#include <stdarg.h>
-#include <stdbool.h>
-#include <signal.h>
-#include <unistd.h>
-#include <limits.h>
-#include <sys/time.h>
-
-#include <systemd/sd-journal.h>
-
-struct tallow_struct {
-	char *ip;
-	int count;
-	struct timeval time;
-	struct tallow_struct *next;
-};
-
-static struct tallow_struct *head;
-
-static struct tallow_struct *whitelist;
-
-#define FILTER_STRING "SYSLOG_IDENTIFIER=sshd"
-
-static char ipt_path[PATH_MAX];
-static int threshold = 3;
-static int expires = 3600;
-static int has_ipv6 = 0;
-static sd_journal *j;
-
-static int ext(char *fmt, ...)
-{
-	va_list args;
-	char cmd[1024];
-	int ret = 0;
-
-	va_start(args, fmt);
-	vsnprintf(cmd, sizeof(cmd), fmt, args);
-	va_end(args);
-
-	ret = system(cmd);
-	if (ret)
-		fprintf(stderr, "Error executing \"%s\": returned %d\n", cmd, ret);
-	return (ret);
-}
-
-static void ext_ignore(char *fmt, ...)
-{
-	va_list args;
-	char cmd[1024];
-
-	va_start(args, fmt);
-	vsnprintf(cmd, sizeof(cmd), fmt, args);
-	va_end(args);
-
-	__attribute__((unused)) int ret = system(cmd);
-}
-
-static void setup(void)
-{
-	static bool done = false;
-	if (done)
-		return;
-	done = true;
-
-	/* init ipset and iptables */
-	/* delete iptables ref to set before the ipset! */
-	ext_ignore("%s/iptables -t filter -D INPUT -m set --match-set tallow src -j DROP 2> /dev/null", ipt_path);
-	ext_ignore("%s/ipset destroy tallow 2> /dev/null", ipt_path);
-	if (ext("%s/ipset create tallow hash:ip family inet timeout %d", ipt_path, expires)) {
-		fprintf(stderr, "Unable to create ipv4 ipset.\n");
-		exit(EXIT_FAILURE);
-	}
-	if (ext("%s/iptables -t filter -A INPUT -m set --match-set tallow src -j DROP", ipt_path)) {
-		fprintf(stderr, "Unable to create iptables rule.\n");
-		exit(EXIT_FAILURE);
-	}
-
-	if (has_ipv6) {
-		ext_ignore("%s/ip6tables -t filter -D INPUT -m set --match-set tallow6 src -j DROP 2> /dev/null", ipt_path);
-		ext_ignore("%s/ipset destroy tallow6 2> /dev/null", ipt_path);
-		if (ext("%s/ipset create tallow6 hash:ip family inet6 timeout %d", ipt_path, expires)) {
-			fprintf(stderr, "Unable to create ipv6 ipset.\n");
-			exit(EXIT_FAILURE);
-		}
-		if (ext("%s/ip6tables -t filter -A INPUT -m set --match-set tallow6 src -j DROP", ipt_path)) {
-			fprintf(stderr, "Unable to create ipt6ables rule.\n");
-			exit(EXIT_FAILURE);
-		}
-	}
-}
-
-static void block(struct tallow_struct *s)
-{
-	if (s->count != threshold)
-		return;
-
-	setup();
-
-	if (strchr(s->ip, ':')) {
-		if (has_ipv6)
-			(void) ext("%s/ipset -A tallow6 %s", ipt_path, s->ip);
-	} else {
-		(void) ext("%s/ipset -A tallow %s", ipt_path, s->ip);
-	}
-
-	fprintf(stderr, "Blocked %s\n", s->ip);
-}
-
-static void whitelist_add(char *ip)
-{
-	struct tallow_struct *w = whitelist;
-	struct tallow_struct *n;
-
-	while (w && w->next)
-		w = w->next;
-
-	n = malloc(sizeof(struct tallow_struct));
-	if (!n) {
-		fprintf(stderr, "Out of memory.\n");
-		exit(EXIT_FAILURE);
-	}
-	memset(n, 0, sizeof(struct tallow_struct));
-	n->ip = strdup(ip);
-	n->next = NULL;
-
-	if (!whitelist)
-		whitelist = n;
-	else
-		w->next = n;
-}
-
-static void find(char *ip)
-{
-	struct tallow_struct *s = head;
-	struct tallow_struct *n;
-	struct tallow_struct *w = whitelist;
-
-	if (!ip)
-		return;
-
-	/*
-	 * not validating the IP address format here, just
-	 * making sure we're not passing special characters
-	 * to system().
-	 */
-	if (strspn(ip, "0123456789abcdef:.") != strlen(ip))
-		return;
-
-	/* whitelist */
-	while (w) {
-		if (!strcmp(w->ip, ip))
-			return;
-		w = w->next;
-	}
-
-	/* walk and update entry */
-	while (s) {
-		if (!strcmp(s->ip, ip)) {
-			s->count++;
-			(void) gettimeofday(&s->time, NULL);
-
-			block(s);
-			return;
-		}
-
-		if (s->next)
-			s = s->next;
-		else
-			break;
-	}
-
-	/* append */
-	n = malloc(sizeof(struct tallow_struct));
-	if (!n) {
-		fprintf(stderr, "Out of memory.\n");
-		exit(EXIT_FAILURE);
-	}
-	memset(n, 0, sizeof(struct tallow_struct));
-
-	if (!head)
-		head = n;
-	else
-		s->next = n;
-
-	n->ip = strdup(ip);
-	n->count = 1;
-	n->next = NULL;
-	(void) gettimeofday(&n->time, NULL);
-
-	block(n);
-	return;
-}
-
-static void sig(int u __attribute__ ((unused)))
-{
-	fprintf(stderr, "Exiting on request.\n");
-	sd_journal_close(j);
-
-	struct tallow_struct *s = head;
-	while (s) {
-		struct tallow_struct *n = NULL;
-
-		free(s->ip);
-		n = s;
-		s = s->next;
-		free(n);
-	}
-	exit(EXIT_SUCCESS);
-}
-
-static void prune(void)
-{
-	struct tallow_struct *s = head;
-	struct tallow_struct *p;
-	struct timeval tv;
-
-	(void) gettimeofday(&tv, NULL);
-	p = NULL;
-
-	while (s) {
-		if ((tv.tv_sec - s->time.tv_sec) > expires) {
-			if (p) {
-				p->next = s->next;
-				free(s->ip);
-				free(s);
-				s = p->next;
-				continue;
-			} else {
-				head = s->next;
-				free(s->ip);
-				free(s);
-				s = head;
-				p = NULL;
-				continue;
-			}
-		}
-		p = s;
-		s = s->next;
-	}
-}
-
-int main(void)
-{
-	int r;
-	FILE *f;
-	struct sigaction s;
-	int timeout = 60;
-
-	strcpy(ipt_path, "/usr/sbin");
-
-	memset(&s, 0, sizeof(struct sigaction));
-	s.sa_handler = sig;
-	sigaction(SIGHUP, &s, NULL);
-	sigaction(SIGTERM, &s, NULL);
-	sigaction(SIGINT, &s, NULL);
-
-	if (access("/proc/sys/net/ipv6", R_OK | X_OK) == 0)
-		has_ipv6 = 1;
-
-	f = fopen("/etc/tallow.conf", "r");
-	if (f) {
-		char buf[256];
-		char *key;
-		char *val;
-
-		while (fgets(buf, 80, f) != NULL) {
-			char *c;
-
-			c = strchr(buf, '\n');
-			if (c) *c = 0; /* remove trailing \n */
-
-			if (buf[0] == '#')
-				continue; /* comment line */
-
-			key = strtok(buf, "=");
-			if (!key)
-				continue;
-			val = strtok(NULL, "=");
-			if (!val)
-				continue;
-
-			// todo: filter leading/trailing whitespace
-
-			if (!strcmp(key, "ipt_path"))
-				strncpy(ipt_path, val, PATH_MAX - 1);
-			if (!strcmp(key, "threshold"))
-				threshold = atoi(val);
-			if (!strcmp(key, "expires"))
-				expires = atoi(val);
-			if (!strcmp(key, "whitelist"))
-				whitelist_add(val);
-			if (!strcmp(key, "ipv6"))
-				has_ipv6 = atoi(val);
-		}
-		fclose(f);
-	}
-
-	if (!has_ipv6)
-		fprintf(stdout, "ipv6 support disabled.\n");
-
-	if (!whitelist)
-		whitelist_add("127.0.0.1");
-
-	r = sd_journal_open(&j, SD_JOURNAL_LOCAL_ONLY);
-	if (r < 0) {
-		fprintf(stderr, "Failed to open journal: %s\n", strerror(-r));
-		exit(EXIT_FAILURE);
-	}
-
-
-	/* ffwd journal */
-	sd_journal_add_match(j, FILTER_STRING, 0);
-	r = sd_journal_seek_tail(j);
-	sd_journal_wait(j, (uint64_t) 0);
-	fprintf(stderr, "sd_journal_seek_tail() returned %d\n", r);
-	while (sd_journal_next(j) != 0)
-		r++;
-	fprintf(stderr, "Forwarded through %d items in the journal to reach the end\n", r);
-
-	fprintf(stderr, "Started\n");
-
-	for (;;) {
-		const void *d;
-		size_t l;
-
-		r = sd_journal_wait(j, (uint64_t) timeout * 1000000);
-		if (r == SD_JOURNAL_INVALIDATE) {
-			fprintf(stderr, "Journal was rotated, resetting\n");
-			sd_journal_seek_tail(j);
-		}
-
-		while (sd_journal_next(j) != 0) {
-			char *t;
-			char *m;
-			int i;
-
-			if (sd_journal_get_data(j, "MESSAGE", &d, &l) < 0) {
-				fprintf(stderr, "Failed to read message field: %s\n", strerror(-r));
-				continue;
-			}
-
-			m = strndup(d, l+1);
-			m[l] = '\0';
-
-			if (strstr(m, "MESSAGE=Failed password for invalid user ")) {
-				t = strtok(m, " ");
-				for (i = 0; i < 7; i++)
-					t = strtok(NULL, " ");
-				find(t);
-			}
-
-			if (strstr(m, "MESSAGE=Failed password for root ")) {
-				t = strtok(m, " ");
-				for (i = 0; i < 5; i++)
-					t = strtok(NULL, " ");
-				find(t);
-			}
-
-			free(m);
-		}
-
-		prune();
-	}
-
-	sd_journal_close(j);
-
-	exit(EXIT_SUCCESS);
-}

tallow.conf

@@ -1,8 +1,9 @@
 
 # tallow.conf - see `man tallow.conf` for more information
 
-#path_iptables=/usr/sbin
-#threshold=3
+#ipt_path=/usr/sbin
 #expires=3600
 #whitelist=127.0.0.1
+#whitelist=192.168.
+#whitelist=10.
 #ipv6=0

tallow.conf.5.md

@@ -1,57 +0,0 @@
-
-## tallow.conf
-
-The tallow configuration file
-
-## NAME
-
-tallow.conf - Tallow daemon configuration file
-
-## SYNOPSIS
-
-`/etc/tallow.conf`
-
-## DESCRIPTION
-
-This file is read on startup by the tallow(1) daemon, and can
-be used to provide options to the tallow daemon. If not present,
-tallow will operate with built-in defaults.
-
-## OPTIONS
-
-`ipt_path`=`<string>`
-Specifies the location of the ipset(1), iptables(1) or ip6tables(1)
-program. By default, tallow will look in "/usr/sbin" for them.
-
-`expires`=`<int>`
-The number of seconds that IP addresses are blocked for. Note that
-due to the implementation, IP addresses may be blocked for much
-longer than this period. If IP addresses are seen, but not
-blocked within this period, they are also removed from the
-watch list. Defaults to 3600s.
-
-`threshold`=`<int>`
-Specifies the number of times an IP address may appear before it
-is blocked. Defaults to 3.
-
-`whitelist`=`<ipv4 address>`
-Specify an IP address that should never be blocked. Multiple IP
-addresses can be included by repeating the `whitelist`
-option several times. By default, only 127.0.0.1 is whitelisted.
-
-`ipv6`=`<0|1>`
-Enable of disable ipv6 (ip6tables) support. Ipv6 is disabled
-automatically on systems that do not appear to have ipv6 support
-and enabled when ipv6 is present. Use this option to explicitly
-disable ipv6 support if your system does not have ipv6 or is
-missing ip6tables. Even with ipv6 disabled, tallow will track
-and log ipv6 addresses.
-
-## SEE ALSO
-
-tallow(1), iptables(1)
-
-## AUTHOR
-
-Auke Kok <auke-jan.h.kok@intel.com>
-