Finalised v1.17

add longer check for xmpp preamble

COPYING

@@ -0,0 +1,339 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
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+
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+
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+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
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+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
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+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
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+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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+
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+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
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+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.

ChangeLog

@@ -1,3 +1,26 @@
+v1.17: 	09MAR2015
+	Support RFC5952-style IPv6 addresses, e.g. [::]:443.
+
+	Transparant proxy support for FreeBSD.
+	(Ruben van Staveren)
+
+	Using -F with no argument will try
+	/etc/sslh/sslh.cfg and then /etc/sslh.cfg as
+	configuration files. (argument to -F can no longer
+	be separated from the option by a space, e.g. must
+	be -Ffoo.cfg)
+
+	Call setgroups() before setgid() (fixes potential
+	privilege escalation).
+	(Lars Vogdt)
+
+	Use portable way of getting modified time for OSX
+	support.
+	(Aaron Madlon-Kay)
+
+	Example configuration for fail2ban.
+	(Every Mouw)
+
 v1.16:	11FEB2014
 	Probes made more resilient, to incoming data
 	containing NULLs. Also made them behave properly

Makefile

@@ -2,7 +2,7 @@
 
 VERSION=$(shell ./genver.sh -r)
 USELIBCONFIG=1	# Use libconfig? (necessary to use configuration files)
-USELIBWRAP=	# Use libwrap?
+USELIBWRAP?=	# Use libwrap?
 USELIBCAP=	# Use libcap?
 COV_TEST= 	# Perform test coverage?
 PREFIX=/usr/local
@@ -75,7 +75,6 @@ install: sslh $(MAN)
 install-debian: install sslh $(MAN)
 	sed -e "s+^PREFIX=+PREFIX=$(PREFIX)+" scripts/etc.init.d.sslh > /etc/init.d/sslh
 	chmod 755 /etc/init.d/sslh
-	cp scripts/etc.default.sslh /etc/default/sslh
 	update-rc.d sslh defaults
 
 uninstall:

README.md

@@ -93,7 +93,8 @@ Installation
 
 		make
 		cp sslh-fork /usr/local/sbin/sslh
-		cp scripts/etc.default.sslh /etc/default/sslh
+		cp basic.cfg /etc/sslh.cfg
+                vi /etc/sslh.cfg
 
 * For Debian:
 
@@ -101,7 +102,7 @@ Installation
 	
 * For CentOS:
 
-		cp scripts/etc.rc.d.init.d.sslh /etc/rc.d/init.d/sslh
+		cp scripts/etc.rc.d.init.d.sslh.centos /etc/rc.d/init.d/sslh
 
 
 You might need to create links in /etc/rc<x>.d so that the server
@@ -113,14 +114,12 @@ start automatically at boot-up, e.g. under Debian:
 Configuration
 =============
 
-You can edit settings in /etc/default/sslh:
-
-	LISTEN=ifname:443
-	SSH=localhost:22
-	SSL=localhost:443
+If you use the scripts provided, sslh will get its
+configuration from /etc/sslh.cfg. Please refer to
+example.cfg for an overview of all the settings.
 
 A good scheme is to use the external name of the machine in
-`$LISTEN`, and bind `httpd` to `localhost:443` (instead of all
+`listen`, and bind `httpd` to `localhost:443` (instead of all
 binding to all interfaces): that way, HTTPS connections
 coming from inside your network don't need to go through
 `sslh`, and `sslh` is only there as a frontal for connections
@@ -151,7 +150,8 @@ To support OpenVPN connexions reliably, it is necessary to
 increase `sslh`'s timeout to 5 seconds.
 
 Instead of using OpenVPN's port sharing, it is more reliable
-to use `sslh`'s `-o` option to get `sslh` to do the port sharing.
+to use `sslh`'s `--openvpn` option to get `sslh` to do the
+port sharing.
 
 Using proxytunnel with sslh
 ---------------------------
@@ -216,13 +216,15 @@ transparent proxying, just don't use it (or use the libcap method).
 Transparent proxy support
 -------------------------
 
-On Linux (only?) you can use the `--transparent` option to
+On Linux and FreeBSD you can use the `--transparent` option to
 request transparent proying. This means services behind `sslh`
 (Apache, `sshd` and so on) will see the external IP and ports
 as if the external world connected directly to them. This
 simplifies IP-based access control (or makes it possible at
 all).
 
+Linux:
+
 `sslh` needs extended rights to perform this: you'll need to
 give it `CAP_NET_ADMIN` capabilities (see appropriate chapter)
 or run it as root (but don't do that).
@@ -240,6 +242,58 @@ this scheme -- let me know if you manage that:
 	# ip rule add fwmark 0x1 lookup 100
 	# ip route add local 0.0.0.0/0 dev lo table 100
 
+Tranparent proxying with IPv6 is similarly set up as follows:
+
+        # ip6tables -t mangle -N SSLH
+        # ip6tables -t mangle -A  OUTPUT --protocol tcp --out-interface eth0 --sport 22 --jump SSLH
+        # ip6tables -t mangle -A OUTPUT --protocol tcp --out-interface eth0 --sport 4443 --jump SSLH
+        # ip6tables -t mangle -A SSLH --jump MARK --set-mark 0x1
+        # ip6tables -t mangle -A SSLH --jump ACCEPT
+        # ip -6 rule add fwmark 0x1 lookup 100
+        # ip -6 route add local ::/0 dev lo table 100
+
+Note that these rules will prevent from connecting directly
+to ssh on the port 22, as packets coming out of sshd will be
+tagged. If you need to retain direct access to ssh on port
+22 as well as through sslh, you can make sshd listen to
+22 AND another port (e.g. 2222), and change the above rules
+accordingly.
+
+FreeBSD:
+
+Given you have no firewall defined yet, you can use the following configuration
+to have ipfw properly redirect traffic back to sslh
+
+	/etc/rc.conf
+	firewall_enable="YES"
+	firewall_type="open"
+	firewall_logif="YES"
+	firewall_coscripts="/etc/ipfw/sslh.rules"
+
+
+/etc/ipfw/sslh.rules
+
+	#! /bin/sh
+
+	# ssl
+	ipfw add 20000 fwd 192.0.2.1,443 log tcp from 192.0.2.1 8443 to any out
+	ipfw add 20010 fwd 2001:db8::1,443 log tcp from 2001:db8::1 8443 to any out
+
+	# ssh
+	ipfw add 20100 fwd 192.0.2.1,443 log tcp from 192.0.2.1 8022 to any out
+	ipfw add 20110 fwd 2001:db8::1,443 log tcp from 2001:db8::1 8022 to any out
+
+	# xmpp
+	ipfw add 20200 fwd 192.0.2.1,443 log tcp from 192.0.2.1 5222 to any out
+	ipfw add 20210 fwd 2001:db8::1,443 log tcp from 2001:db8::1 5222 to any out
+
+	# openvpn (running on other internal system)
+	ipfw add 20300 fwd 192.0.2.1,443 log tcp from 198.51.100.7 1194 to any out
+	ipfw add 20310 fwd 2001:db8::1,443 log tcp from 2001:db8:1::7 1194 to any out
+
+General notes:
+
+
 This will only work if `sslh` does not use any loopback
 addresses (no `127.0.0.1` or `localhost`), you'll need to use
 explicit IP addresses (or names):
@@ -250,6 +304,18 @@ This will not work:
 
 	sslh --listen 192.168.0.1:443 --ssh 127.0.0.1:22 --ssl 127.0.0.1:4443
 
+Fail2ban
+--------
+
+If using transparent proxying, just use the standard ssh
+rules. If you can't or don't want to use transparent
+proxying, you can set `fail2ban` rules to block repeated ssh
+connections from a same IP address (obviously this depends
+on the site, there might be legimite reasons you would get
+many connections to ssh from the same IP address...)
+
+See example files in scripts/fail2ban.
+
 Comments? Questions?
 ====================
 

basic.cfg

@@ -6,7 +6,7 @@ foreground: false;
 inetd: false;
 numeric: false;
 transparent: false;
-timeout: 2;
+timeout: "2";
 user: "nobody";
 pidfile: "/var/run/sslh.pid";
 

common.c

@@ -6,6 +6,7 @@
 
 #define _GNU_SOURCE
 #include <stdarg.h>
+#include <grp.h>
 
 #include "common.h"
 #include "probe.h"
@@ -119,8 +120,20 @@ int bind_peer(int fd, int fd_from)
      * got here */
     res = getpeername(fd_from, from.ai_addr, &from.ai_addrlen);
     CHECK_RES_RETURN(res, "getpeername");
+#ifndef IP_BINDANY /* use IP_TRANSPARENT */
     res = setsockopt(fd, IPPROTO_IP, IP_TRANSPARENT, &trans, sizeof(trans));
     CHECK_RES_DIE(res, "setsockopt");
+#else
+    if (from.ai_addr->sa_family==AF_INET) { /* IPv4 */
+        res = setsockopt(fd, IPPROTO_IP, IP_BINDANY, &trans, sizeof(trans));
+        CHECK_RES_RETURN(res, "setsockopt IP_BINDANY");
+#ifdef IPV6_BINDANY
+    } else { /* IPv6 */
+        res = setsockopt(fd, IPPROTO_IPV6, IPV6_BINDANY, &trans, sizeof(trans));
+        CHECK_RES_RETURN(res, "setsockopt IPV6_BINDANY");
+#endif /* IPV6_BINDANY */
+    }
+#endif /* IP_TRANSPARENT / IP_BINDANY */
     res = bind(fd, from.ai_addr, from.ai_addrlen);
     CHECK_RES_RETURN(res, "bind");
 
@@ -133,15 +146,28 @@ int bind_peer(int fd, int fd_from)
  * of new file descriptor. */
 int connect_addr(struct connection *cnx, int fd_from)
 {
-    struct addrinfo *a;
+    struct addrinfo *a, from;
+    struct sockaddr_storage ss;
     char buf[NI_MAXHOST];
     int fd, res;
 
+    memset(&from, 0, sizeof(from));
+    from.ai_addr = (struct sockaddr*)&ss;
+    from.ai_addrlen = sizeof(ss);
+
+    res = getpeername(fd_from, from.ai_addr, &from.ai_addrlen);
+    CHECK_RES_RETURN(res, "getpeername");
+
     for (a = cnx->proto->saddr; a; a = a->ai_next) {
+        /* When transparent, make sure both connections use the same address family */
+        if (transparent && a->ai_family != from.ai_addr->sa_family)
+            continue;
         if (verbose) 
             fprintf(stderr, "connecting to %s family %d len %d\n", 
                     sprintaddr(buf, sizeof(buf), a),
                     a->ai_addr->sa_family, a->ai_addrlen);
+
+        /* XXX Needs to match ai_family from fd_from when being transparent! */
         fd = socket(a->ai_family, SOCK_STREAM, 0);
         if (fd == -1) {
             log_message(LOG_ERR, "forward to %s failed:socket: %s\n",
@@ -155,6 +181,7 @@ int connect_addr(struct connection *cnx, int fd_from)
             if (res == -1) {
                 log_message(LOG_ERR, "forward to %s failed:connect: %s\n", 
                             cnx->proto->description, strerror(errno));
+                close(fd);
             } else {
                 return fd;
             }
@@ -347,21 +374,31 @@ fullname: input string -- it gets clobbered
 */
 void resolve_name(struct addrinfo **out, char* fullname)
 {
-   char *serv, *host;
+   char *serv, *host, *end;
    int res;
 
+   /* Find port */
    char *sep = strrchr(fullname, ':');
-
-   if (!sep) /* No separator: parameter is just a port */
-   {
+   if (!sep) { /* No separator: parameter is just a port */
       fprintf(stderr, "%s: names must be fully specified as hostname:port\n", fullname);
       exit(1);
    }
-
-   host = fullname;
    serv = sep+1;
    *sep = 0;
 
+   host = fullname;
+
+   /* If it is a RFC-Compliant IPv6 address ("[1234::12]:443"), remove brackets
+    * around IP address */
+   if (host[0] == '[') {
+       end = strrchr(host, ']');
+       if (!end) {
+           fprintf(stderr, "%s: no closing bracket in IPv6 address?\n", host);
+       }
+       host++; /* skip first bracket */
+       *end = 0; /* remove last bracket */
+   }
+
    res = resolve_split_name(out, host, serv);
    if (res) {
       fprintf(stderr, "%s `%s'\n", gai_strerror(res), fullname);
@@ -577,6 +614,13 @@ void drop_privileges(const char* user_name)
 
     set_keepcaps(1);
 
+    /* remove extraneous groups in case we belong to several extra groups that
+     * may have unwanted rights. If non-root when calling setgroups(), it
+     * fails, which is fine because... we have no unwanted rights 
+     * (see POS36-C for security context)
+     * */
+    setgroups(0, NULL);
+
     res = setgid(pw->pw_gid);
     CHECK_RES_DIE(res, "setgid");
     res = setuid(pw->pw_uid);

example.cfg

@@ -8,7 +8,7 @@ foreground: true;
 inetd: false;
 numeric: false;
 transparent: false;
-timeout: 2;
+timeout: "2";
 user: "nobody";
 pidfile: "/var/run/sslh.pid";
 

genver.sh

@@ -1,4 +1,4 @@
-#! /bin/bash
+#! /bin/sh
 
 if [ ${#} -eq 1 ] && [ "x$1" = "x-r" ]; then
 	# release text only
@@ -10,10 +10,19 @@ fi
 if ! `(git status | grep -q "On branch") 2> /dev/null`; then
         # If we don't have git, we can't work out what
         # version this is. It must have been downloaded as a
-        # zip file. Github creates the zip file with all
-        # files dated from the last change: use the
-        # Makefile's modification time as a release number
-	release=zip-`stat -c "%y" Makefile | sed 's/ .*//'`
+        # zip file. 
+        
+        # If downloaded from the release page, the directory
+        # has the version number.
+        release=`pwd | sed s/.*sslh-// | grep "[[:digit:]]"`
+        
+        if [ "x$release" = "x" ]; then
+            # If downloaded from the head, Github creates the
+            # zip file with all files dated from the last
+            # change: use the Makefile's modification time as a
+            # release number
+            release=head-`perl -MPOSIX -e 'print strftime "%Y-%m-%d",localtime((stat "Makefile")[9])'`
+        fi
 fi
 
 if head=`git rev-parse --verify HEAD 2>/dev/null`; then

probe.c

@@ -169,7 +169,10 @@ static int is_tinc_protocol( const char *p, int len, struct proto *proto)
  * */
 static int is_xmpp_protocol( const char *p, int len, struct proto *proto)
 {
-    if (len < 6)
+    /* sometimes the word 'jabber' shows up late in the initial string,
+       sometimes after a newline. this makes sure we snarf the entire preamble
+       and detect it. (fixed for adium/pidgin) */
+    if (len < 50)
         return PROBE_AGAIN;
 
     return memmem(p, len, "jabber", 6) ? 1 : 0;
@@ -229,7 +232,7 @@ static int regex_probe(const char *p, int len, struct proto *proto)
     for (; *probe && regexec(*probe, p, 0, &pos, REG_STARTEND); probe++)
         /* try them all */;
 
-    return (probe != NULL);
+    return (*probe != NULL);
 }
 
 /* 

scripts/etc.default.sslh

@@ -1,5 +0,0 @@
-LISTEN=ifname:443
-SSH=localhost:22
-SSL=localhost:443
-USER=nobody
-PID=/var/run/sslh.pid

scripts/etc.init.d.sslh

@@ -27,7 +27,7 @@ DAEMON=$PREFIX/sbin/sslh
 start()
 {
         echo "Start services: sslh"
-        $DAEMON --user ${USER} --pidfile ${PID} --listen ${LISTEN} --ssh ${SSH} --ssl ${SSL}
+        $DAEMON -F /etc/sslh.cfg
         logger -t ${tag} -p ${facility} -i 'Started sslh'
 }
 

scripts/fail2ban/jail.conf

@@ -0,0 +1,9 @@
+# Add the following to your fail2ban jail.conf
+# In Debian you'd append it to /etc/fail2ban/jail.local
+
+[sslh-ssh]
+enabled = true
+filter = sslh-ssh
+action = iptables-multiport[name=sslh,port="443"]
+logpath = /var/log/messages
+maxretry = 5

scripts/fail2ban/sslh-ssh.conf

@@ -0,0 +1,25 @@
+# Add the following to you fail2ban configuration file
+# In Debian it'd go in /etc/fail2ban/filter.d/sslh-ssh.conf
+
+
+# Fail2Ban filter for sslh demultiplexed ssh
+#
+# Doesn't (and cannot) detect auth errors,
+# but many connection attempts from the same
+# origin is reason enough to block.
+#
+# Verion: 2014-03-28
+
+[INCLUDES]
+
+# no includes
+
+[Definition]
+
+failregex = ^.+ sslh\[.+\]: connection from <HOST>:.+ to .+ forwarded
+from .+ to .+:ssh\s*$
+
+ignoreregex =
+
+# Author: Evert Mouw <post@evert.net>
+

sslh-main.c

@@ -2,7 +2,7 @@
 # main: processing of config file, command line options and start the main
 # loop.
 #
-# Copyright (C) 2007-2012  Yves Rutschle
+# Copyright (C) 2007-2014  Yves Rutschle
 # 
 # This program is free software; you can redistribute it
 # and/or modify it under the terms of the GNU General Public
@@ -33,7 +33,7 @@
 const char* USAGE_STRING =
 "sslh " VERSION "\n" \
 "usage:\n" \
-"\tsslh  [-v] [-i] [-V] [-f] [-n] [-F <file>]\n"
+"\tsslh  [-v] [-i] [-V] [-f] [-n] [--transparent] [-F <file>]\n"
 "\t[-t <timeout>] [-P <pidfile>] -u <username> -p <add> [-p <addr> ...] \n" \
 "%s\n\n" /* Dynamically built list of builtin protocols */  \
 "\t[--on-timeout <addr>]\n" \
@@ -41,12 +41,13 @@ const char* USAGE_STRING =
 "-V: version\n" \
 "-f: foreground\n" \
 "-n: numeric output\n" \
+"-u: specify under which user to run\n" \
+"--transparent: behave as a transparent proxy\n" \
 "-F: use configuration file\n" \
 "--on-timeout: connect to specified address upon timeout (default: ssh address)\n" \
 "-t: seconds to wait before connecting to --on-timeout address.\n" \
 "-p: address and port to listen on.\n    Can be used several times to bind to several addresses.\n" \
 "--[ssh,ssl,...]: where to connect connections from corresponding protocol.\n" \
-"-F: specify a configuration file\n" \
 "-P: PID file.\n" \
 "-i: Run as a inetd service.\n" \
 "";
@@ -62,7 +63,7 @@ static struct option const_options[] = {
     { "numeric",    no_argument,            &numeric,       1 },
     { "verbose",    no_argument,            &verbose,       1 },
     { "user",       required_argument,      0,              'u' },
-    { "config",     required_argument,      0,              'F' },
+    { "config",     optional_argument,      0,              'F' },
     { "pidfile",    required_argument,      0,              'P' },
     { "timeout",    required_argument,      0,              't' },
     { "on-timeout", required_argument,      0,              OPT_ONTIMEOUT },
@@ -71,7 +72,7 @@ static struct option const_options[] = {
 };
 static struct option* all_options;
 static struct proto* builtins;
-static const char *optstr = "vt:T:p:VP:F:";
+static const char *optstr = "vt:T:p:VP:F::";
 
 
 
@@ -279,11 +280,14 @@ static int config_parse(char *filename, struct addrinfo **listen, struct proto *
 
     config_init(&config);
     if (config_read_file(&config, filename) == CONFIG_FALSE) {
-        fprintf(stderr, "%s:%d:%s\n", 
+        if (config_error_type(&config) == CONFIG_ERR_PARSE) {
+            fprintf(stderr, "%s:%d:%s\n", 
                     filename,
                     config_error_line(&config),
                     config_error_text(&config));
-        exit(1);
+            exit(1);
+        }
+        return 1;
     }
 
     config_lookup_bool(&config, "verbose", &verbose);
@@ -361,8 +365,18 @@ static void cmdline_config(int argc, char* argv[], struct proto** prots)
     while ((c = getopt_long_only(argc, argv, optstr, all_options, NULL)) != -1) {
         if (c == 'F') {
             config_filename = optarg;
-            /* find the end of the listen list */
-            res = config_parse(config_filename, &addr_listen, prots);
+            if (config_filename) {
+                fprintf(stderr, "config: %s\n", config_filename);
+                res = config_parse(config_filename, &addr_listen, prots);
+            } else {
+                /* No configuration file specified -- try default file locations */
+                res = config_parse("/etc/sslh/sslh.cfg", &addr_listen, prots);
+                if (!res && verbose) fprintf(stderr, "Using /etc/sslh/sslh.cfg\n");
+                if (res) {
+                    res = config_parse("/etc/sslh.cfg", &addr_listen, prots);
+                    if (!res && verbose) fprintf(stderr, "Using /etc/sslh.cfg\n");
+                }
+            }
             if (res)
                 exit(4);
             break;

sslh.pod

@@ -6,7 +6,7 @@
 
 =head1 SYNOPSIS
 
-sslh [B<-F> I<config file>] [ B<-t> I<num> ] [B<-p> I<listening address> [B<-p> I<listening address> ...] [B<--ssl> I<target address for SSL>] [B<--ssh> I<target address for SSH>] [B<--openvpn> I<target address for OpenVPN>] [B<--http> I<target address for HTTP>] [B<--anyprot> I<default target address>] [B<--on-timeout> I<protocol name>] [B<-u> I<username>] [B<-P> I<pidfile>] [-v] [-i] [-V] [-f] [-n]
+sslh [B<-F> I<config file>] [ B<-t> I<num> ] [B<--transparent>] [B<-p> I<listening address> [B<-p> I<listening address> ...] [B<--ssl> I<target address for SSL>] [B<--ssh> I<target address for SSH>] [B<--openvpn> I<target address for OpenVPN>] [B<--http> I<target address for HTTP>] [B<--anyprot> I<default target address>] [B<--on-timeout> I<protocol name>] [B<-u> I<username>] [B<-P> I<pidfile>] [-v] [-i] [-V] [-f] [-n]
 
 =head1 DESCRIPTION
 
@@ -72,10 +72,22 @@ If no data is sent by the client, B<sslh> will eventually
 time out and connect to the protocol specified with
 B<--on-timeout>, or I<ssh> if none is specified.
 
+=head2 Logging
+
+As a security/authorization program, B<sslh> logs to the
+LOG_AUTH facility, with priority LOG_INFO for normal
+connections and LOG_ERR for failures.
+
 =head1 OPTIONS
 
 =over 4
 
+=item B<-F> I<filename>, B<--config> I<filename>
+
+Uses I<filename> has configuration file. If other
+command-line options are specified, they will override the
+configuration file's settings.
+
 =item B<-t> I<num>, B<--timeout> I<num>
 
 Timeout before forwarding the connection to the timeout
@@ -86,6 +98,13 @@ protocol (which should usually be SSH). Default is 2s.
 Name of the protocol to connect to after the timeout period
 is over. Default is 'ssh'.
 
+=item B<--transparent>
+
+Makes B<sslh> behave as a transparent proxy, i.e. the
+receiving service sees the original client's IP address.
+This works on Linux only and involves B<iptables> settings.
+Refer to the README for more information.
+
 =item B<-p> I<listening address>, B<--listen> I<listening address>
 
 Interface and port on which to listen, e.g. I<foobar:443>,

t

@@ -295,21 +295,6 @@ if ($RB_OPEN_PID_FILE) {
     is($code, 3, "Exit status if can't open PID file");
 }
 
-# Robustness: Can't bind address
-if ($RB_BIND_ADDRESS) {
-    print "***Test: Can't bind address\n";
-    my $sslh_pid;
-    if (!($sslh_pid = fork)) {
-        my $user = (getpwuid $<)[0]; # Run under current username
-        exec "./sslh-select -v -f -u $user --listen 74.125.39.106:9000 --ssh $ssh_address --ssl $ssl_address -P $pidfile";
-    }
-    warn "spawned $sslh_pid\n";
-    waitpid $sslh_pid, 0;
-    my $code = $? >> 8;
-    warn "exited with $code\n";
-    is($code, 1, "Exit status if can't bind address");
-}
-
 # Robustness: Can't resolve address
 if ($RB_RESOLVE_ADDRESS) {
     print "***Test: Can't resolve address\n";