Problema ao redirecionar porta 80

[felixleonardo]

Caros amigos, sou novo por aqui e gostaria de pedir uma ajudinha a vocês.
Desculpem o post longo, mas é que quero ser o mais claro possível para ajudar vocês a me ajudarem.
Na empresa onde trabalho, estou configurando um servidor WEB (192.168.20.2) que se localiza na rede interna atrás de um Servidor com Firewall ativada (200.xxx.xxx.xxx).
A máquina onde está o Apache consegue acessar a Internet normalmente e pingar no Gateway, ou seja, a Firewall permite acesso à Internet normalmente.
O problema está na necessidade de que as pessoas de fora da rede (pela Internet) possam acessar a página deste servidor WEB. Preciso para isso redirecionar os pedidos que chegarem na porta 80 do Gateway (200.xxx.xxx.xxx) para a porta 80 do Servidor WEB (192.168.20.2).
Já fiz esse redirecionamente, mas não sei se o fiz corretamente, pois ao tentar acessar o IP do Gateway de uma máquina externa, surge a mensagem:
Atingido o tempo limite de conexão
O servidor 200.xxx.xxx.xxx está demorando muito para responder.
O que poderia ser este problema?
Abaixo posto o script de Firewall do Gateway da empresa. Ele é enorme, e entendo muito pouco de iptables para encontrar o problema.
Quem puder ajudar, agradeço muito a imensa paciência e boa vontade!!!

[felixleonardo]

#!/bin/sh
#
# rc.firewall-2.4-stronger
#
FWVER=0.74s-4

# An example of a stronger IPTABLES firewall with IP Masquerade
# support for 2.4.x kernels.
#
# Log:
# 0.74s - Changed the EXTIP command to work on NON-English distros
# 0.73s - Added comments in the output section that DHCPd is optional
# and changed the default settings to disabled
# 0.72s - Changed the filter from the INTNET to the INTIP to be
# stateful; moved the command VARs to the top and made the
# rest of the script to use them
# 0.70s - Added a disabled examples for allowing internal DHCP
# and external WWW access to the server
# 0.63s - Added support for the IRC module
# 0.62s - Initial version based upon the basic 2.4.x rc.firewall


echo -e "\nLoading STRONGER rc.firewall - version $FWVER..\n"


# The location of various iptables and other shell programs
#
# If your Linux distribution came with a copy of iptables, most
# likely it is located in /sbin. If you manually compiled
# iptables, the default location is in /usr/local/sbin
#
# ** Please use the "whereis iptables" command to figure out
# ** where your copy is and change the path below to reflect
# ** your setup
#
IPTABLES=/sbin/iptables
#
LSMOD=/sbin/lsmod
DEPMOD=/sbin/depmod
INSMOD=/sbin/insmod
GREP=/bin/grep
AWK=/bin/awk
SED=/bin/sed
IFCONFIG=/sbin/ifconfig


#Setting the EXTERNAL and INTERNAL interfaces for the network
#
# Each IP Masquerade network needs to have at least one
# external and one internal network. The external network
# is where the natting will occur and the internal network
# should preferably be addressed with a RFC1918 private address
# scheme.
#
# For this example, "eth0" is external and "eth1" is internal"
#
# NOTE: If this doesnt EXACTLY fit your configuration, you must
# change the EXTIF or INTIF variables above. For example:
#
# EXTIF="ppp0"
#
# if you are a modem user.
#
EXTIF="eth0"
INTIF="eth1"
echo " External Interface: $EXTIF"
echo " Internal Interface: $INTIF"
echo " ---"

# Specify your Static IP address here or let the script take care of it
# for you.
#
EXTIP="200.xxx.xxx.xxx"
echo " External IP: $EXTIP"
echo " ---"


# Assign the internal TCP/IP network and IP address
INTNET="192.168.20.0/24"
INTIP="192.168.20.1/24"
echo " Internal Network: $INTNET"
echo " Internal IP: $INTIP"
echo " ---"




# Setting a few other local variables
#
UNIVERSE="0.0.0.0/0"
UP_PORTS="1024:"
D_PORTS=":1024"

#================================== =================================== =
#== No editing beyond this line is required for initial MASQ testing ==

# Need to verify that all modules have all required dependencies
#
echo " - Verifying that all kernel modules are ok"
$DEPMOD -a

echo -en " Loading kernel modules: "

# With the new IPTABLES code, the core MASQ functionality is now either
# modular or compiled into the kernel. This HOWTO shows ALL IPTABLES
# options as MODULES. If your kernel is compiled correctly, there is
# NO need to load the kernel modules manually.
#
# NOTE: The following items are listed ONLY for informational reasons.
# There is no reason to manual load these modules unless your
# kernel is either mis-configured or you intentionally disabled
# the kernel module autoloader.
#

# Upon the commands of starting up IP Masq on the server, the
# following kernel modules will be automatically loaded:
#
# NOTE: Only load the IP MASQ modules you need. All current IP MASQ
# modules are shown below but are commented out from loading.
# =================================== ============================

#Load the main body of the IPTABLES module - "ip_tables"
# - Loaded automatically when the "iptables" command is invoked
#
# - Loaded manually to clean up kernel auto-loading timing issues
#
echo -en "ip_tables, "
#
#Verify the module isn't loaded. If it is, skip it
#
if [ -z "` $LSMOD | $GREP ip_tables | $AWK {'print $1'} `" ]; then
$INSMOD ip_tables
fi


#Load the IPTABLES filtering module - "iptable_filter"
#
# - Loaded automatically when filter policies are activated


#Load the stateful connection tracking framework - "ip_conntrack"
#
# The conntrack module in itself does nothing without other specific
# conntrack modules being loaded afterwards such as the "ip_conntrack_ftp"
# module
#
# - This module is loaded automatically when MASQ functionality is
# enabled
#
# - Loaded manually to clean up kernel auto-loading timing issues
#
echo -en "ip_conntrack, "
#
#Verify the module isn't loaded. If it is, skip it
#
if [ -z "` $LSMOD | $GREP ip_conntrack | $AWK {'print $1'} `" ]; then
$INSMOD ip_conntrack
fi


#Load the FTP tracking mechanism for full FTP tracking
#
# Enabled by default -- insert a "#" on the next line to deactivate
#
echo -e "ip_conntrack_ftp, "
#
#Verify the module isn't loaded. If it is, skip it
#
if [ -z "` $LSMOD | $GREP ip_conntrack_ftp | $AWK {'print $1'} `" ]; then
$INSMOD ip_conntrack_ftp
fi


#Load the IRC tracking mechanism for full IRC tracking
#
# Enabled by default -- insert a "#" on the next line to deactivate
#
echo -en " ip_conntrack_irc, "
#
#Verify the module isn't loaded. If it is, skip it
#
if [ -z "` $LSMOD | $GREP ip_conntrack_irc | $AWK {'print $1'} `" ]; then
$INSMOD ip_conntrack_irc
fi


#Load the general IPTABLES NAT code - "iptable_nat"
# - Loaded automatically when MASQ functionality is turned on
#
# - Loaded manually to clean up kernel auto-loading timing issues
#
echo -en "iptable_nat, "
#
#Verify the module isn't loaded. If it is, skip it
#
if [ -z "` $LSMOD | $GREP iptable_nat | $AWK {'print $1'} `" ]; then
$INSMOD iptable_nat
fi


#Loads the FTP NAT functionality into the core IPTABLES code
# Required to support non-PASV FTP.
#
# Enabled by default -- insert a "#" on the next line to deactivate
#
echo -e "ip_nat_ftp"
#
#Verify the module isn't loaded. If it is, skip it
#
if [ -z "` $LSMOD | $GREP ip_nat_ftp | $AWK {'print $1'} `" ]; then
$INSMOD ip_nat_ftp
fi

echo " ---"

# Just to be complete, here is a list of the remaining kernel modules
# and their function. Please note that several modules should be only
# loaded by the correct master kernel module for proper operation.
# --------------------------------------------------------------------
#
# ipt_mark - this target marks a given packet for future action.
# This automatically loads the ipt_MARK module
#
# ipt_tcpmss - this target allows to manipulate the TCP MSS
# option for braindead remote firewalls.
# This automatically loads the ipt_TCPMSS module
#
# ipt_limit - this target allows for packets to be limited to
# to many hits per sec/min/hr
#
# ipt_multiport - this match allows for targets within a range
# of port numbers vs. listing each port individually
#
# ipt_state - this match allows to catch packets with various
# IP and TCP flags set/unset
#
# ipt_unclean - this match allows to catch packets that have invalid
# IP/TCP flags set
#
# iptable_filter - this module allows for packets to be DROPped,
# REJECTed, or LOGged. This module automatically
# loads the following modules:
#
# ipt_LOG - this target allows for packets to be
# logged
#
# ipt_REJECT - this target DROPs the packet and returns
# a configurable ICMP packet back to the
# sender.
#
# iptable_mangle - this target allows for packets to be manipulated
# for things like the TCPMSS option, etc.


#CRITICAL: Enable IP forwarding since it is disabled by default since
#
# Redhat Users: you may try changing the options in
# /etc/sysconfig/network from:
#
# FORWARD_IPV4=false
# to
# FORWARD_IPV4=true
#
echo " Enabling forwarding.."
echo "1" > /proc/sys/net/ipv4/ip_forward

[felixleonardo]

################################### ################################### #######
#
# Enable Stronger IP forwarding and Masquerading
#
# NOTE: In IPTABLES speak, IP Masquerading is a form of SourceNAT or SNAT.
#
# NOTE #2: The following is an example for an internal LAN address in the
# 192.168.1.x network with a 255.255.255.0 or a "24" bit subnet
# mask connecting to the Internet on external interface "eth0".
# This example will MASQ internal traffic out to the Internet
# but not allow non-initiated traffic into your internal network.
#
#
# ** Please change the above network numbers, subnet mask, and your
# *** Internet connection interface name to match your setup
#

#Clearing any previous configuration
#
# Unless specified, the defaults for INPUT, OUTPUT, and FORWARD to DROP.
#
# You CANNOT change this to REJECT as it isn't a vaild setting for a
# policy. If you want REJECT, you must explictly REJECT at the end
# of a giving INPUT, OUTPUT, or FORWARD chain
#
echo " Clearing any existing rules and setting default policy to DROP.."
$IPTABLES -P INPUT DROP
$IPTABLES -F INPUT
$IPTABLES -P OUTPUT DROP
$IPTABLES -F OUTPUT
$IPTABLES -P FORWARD DROP
$IPTABLES -F FORWARD
$IPTABLES -F -t nat

#Not needed and it will only load the unneeded kernel module
#$IPTABLES -F -t mangle
#
# Flush the user chain.. if it exists
if [ -n "`$IPTABLES -L | $GREP drop-and-log-it`" ]; then
$IPTABLES -F drop-and-log-it
fi
#
# Delete all User-specified chains
$IPTABLES -X
#
# Reset all IPTABLES counters
$IPTABLES -Z


#Configuring specific CHAINS for later use in the ruleset
#
# NOTE: Some users prefer to have their firewall silently
# "DROP" packets while others prefer to use "REJECT"
# to send ICMP error messages back to the remote
# machine. The default is "REJECT" but feel free to
# change this below.
#
# NOTE: Without the --log-level set to "info", every single
# firewall hit will goto ALL vtys. This is a very big
# pain.
#
echo " Creating a DROP chain.."
$IPTABLES -N drop-and-log-it
$IPTABLES -A drop-and-log-it -j LOG --log-level info
$IPTABLES -A drop-and-log-it -j DROP

echo -e "\n - Loading INPUT rulesets"


################################### ################################### #
# INPUT: Incoming traffic from various interfaces. All rulesets are
# already flushed and set to a default policy of DROP.
#

# loopback interfaces are valid.
#
$IPTABLES -A INPUT -i lo -s $UNIVERSE -d $UNIVERSE -j ACCEPT


# local interface, local machines, going anywhere is valid
#
$IPTABLES -A INPUT -i $INTIF -s $INTNET -d $UNIVERSE -j ACCEPT


# remote interface, claiming to be local machines, IP spoofing, get lost
#
$IPTABLES -A INPUT -i $EXTIF -s $INTNET -d $UNIVERSE -j drop-and-log-it


# external interface, from any source, for ICMP traffic is valid
#
# If you would like your machine to "ping" from the Internet,
# enable this next line
#
#$IPTABLES -A INPUT -i $EXTIF -p ICMP -s $UNIVERSE -d $EXTIP -j ACCEPT


# Allow any related traffic coming back to the MASQ server in
#
$IPTABLES -A INPUT -i $EXTIF -s $UNIVERSE -d $EXTIP -m state --state \
ESTABLISHED,RELATED -j ACCEPT


# ----- Begin OPTIONAL Section -----
#
# HTTPd - Enable the following lines if you run an EXTERNAL WWW server
#
#echo -e " - Allowing EXTERNAL access to the WWW server"
$IPTABLES -A INPUT -i $EXTIF -m state --state NEW,ESTABLISHED,RELATED \
-p tcp -s $UNIVERSE -d $EXTIP --dport 80 -j ACCEPT
#
# echo -e " - Allowing sendmail for external mail "
# $IPTABLES -A INPUT -i $EXTIF -m state --state NEW,ESTABLISHED,RELATED \
# -p tcp -s $UNIVERSE -d $EXTIP --dport 25 -j ACCEPT

#
# SSHd - Enable the followin lines if you run an EXTERNAL SSH server
#
$IPTABLES -A INPUT -i $EXTIF -m state --state NEW,ESTABLISHED,RELATED \
-p tcp -s $UNIVERSE -d $EXTIP --dport 22 -j ACCEPT
#
#
# IMAPd - Enable the following lines if you run an EXTERNAL imap server
#
#echo -e " - Allowing EXTERNAL access to the IMAP server"
# $IPTABLES -A INPUT -i $EXTIF -m state --state NEW,ESTABLISHED,RELATED \
# -p tcp -s $UNIVERSE -d $EXTIP --dport 143 -j ACCEPT

# Allow access to hight ports
$IPTABLES -A INPUT -i $EXTIF -m state --state NEW,ESTABLISHED,RELATED \
-p udp -s $UNIVERSE -d $EXTIP --dport $UP_PORTS -j ACCEPT
$IPTABLES -A INPUT -i $EXTIF -m state --state NEW,ESTABLISHED,RELATED \
-p tcp -s $UNIVERSE -d $EXTIP --dport $UP_PORTS -j ACCEPT
# $IPTABLES -A INPUT -i $EXTIF -m state --state NEW,ESTABLISHED,RELATED \
# -p tcp -s $UNIVERSE -d $EXTIP --dport 8080 -j ACCEPT
# $IPTABLES -A INPUT -i $EXTIF -m state --state NEW,ESTABLISHED,RELATED \
# -p tcp -s $UNIVERSE -d $EXTIP --dport 8090 -j ACCEPT

#
# ----- End OPTIONAL Section -----



# Catch all rule, all other incoming is denied and logged.
#
$IPTABLES -A INPUT -s $UNIVERSE -d $UNIVERSE -j drop-and-log-it

echo -e " - Loading OUTPUT rulesets"

################################### ################################### #
# OUTPUT: Outgoing traffic from various interfaces. All rulesets are
# already flushed and set to a default policy of DROP.
#

# loopback interface is valid.
#
$IPTABLES -A OUTPUT -o lo -s $UNIVERSE -d $UNIVERSE -j ACCEPT


# local interfaces, any source going to local net is valid
#
$IPTABLES -A OUTPUT -o $INTIF -s $EXTIP -d $INTNET -j ACCEPT


# local interface, any source going to local net is valid
#
$IPTABLES -A OUTPUT -o $INTIF -s $INTIP -d $INTNET -j ACCEPT


# outgoing to local net on remote interface, stuffed routing, deny
#
$IPTABLES -A OUTPUT -o $EXTIF -s $UNIVERSE -d $INTNET -j drop-and-log-it


# anything else outgoing on remote interface is valid
#
$IPTABLES -A OUTPUT -o $EXTIF -s $EXTIP -d $UNIVERSE -j ACCEPT


# Catch all rule, all other outgoing is denied and logged.
#
$IPTABLES -A OUTPUT -s $UNIVERSE -d $UNIVERSE -j drop-and-log-it


echo -e " - Loading FORWARD rulesets"

################################### ################################### #
# FORWARD: Enable Forwarding and thus IPMASQ
#

echo " - FWD: Allow all connections OUT and only existing/related IN"
$IPTABLES -A FORWARD -i $EXTIF -o $INTIF -m state --state ESTABLISHED,RELATED \
-j ACCEPT
$IPTABLES -A FORWARD -i $INTIF -o $EXTIF -j ACCEPT

# Catch all rule, all other forwarding is denied and logged.
#
$IPTABLES -A FORWARD -j drop-and-log-it

# Allow access to hight ports
$IPTABLES -A FORWARD -i $EXTIF -o $INTIF -p tcp --dport $UP_PORTS -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -o $INTIF -p udp --dport $UP_PORTS -j ACCEPT

echo " - NAT: Enabling SNAT (MASQUERADE) functionality on $EXTIF"
#
#More liberal form
$IPTABLES -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE
#
#Stricter form
#$IPTABLES -t nat -A POSTROUTING -o $EXTIF -j SNAT --to $EXTIP

echo "Redirecting WWW port to the internal network"
$IPTABLES -t nat -A PREROUTING -p tcp -i $EXTIF --dport 80 -j DNAT --to 192.168.20.2
$IPTABLES -t nat -A POSTROUTING -d 192.168.20.2 -j SNAT --to 192.168.20.1

################################### ################################### #
echo -e "\nStronger rc.firewall-2.4 $FWVER done.\n"

[zenun]

Ola amigo,

Olha bem grande esse script, e isso só dificulta a manutenção.
Porém existe uma parte ali onde tem uma regra drop-and-log-it que está no final da chain forward! Tudo o que não foi identificado antes será dropado!

Basicamente não é só colocar as regras nas chains PRE e POSTROUTING da tabela nat, é necessário aceitar esse trafego na chain FORWARD da tabela filter! E como a chain drop-and-log-it dropa tudo o que não estiver identificado você não consegue acessar o servidor!

As suas regras de redirecionamento eu as deixaria assim:

$IPTABLES -t nat -A PREROUTING -p tcp -s <ip externo> --dport 80 -j DNAT --to 192.168.20.2
$IPTABLES -t nat -A POSTROUTING -s 192.168.20.2 -j SNAT --to <ip externo>

E além dessas regras falta essa para aceitar o trafego:

iptables -t filter -I FORWARD -d 192.168.20.2 -p tcp --dport 80 -j ACCEPT
iptables -t filter -I FORWARD -s 192.168.20.2 -p tcp --sport 80 -j ACCEPT

Testa aee

[felixleonardo]

Caro amigo zenun!!

É, eu sei que está grande, mas como é da empresa, eu não quero mexer muito, sabe como é...

Cara, faz muito sentido o que você me falou, não tinha reparado nessa regra. Vou tentar aplicar essas regras e respondo se deu certo ou não. Tomara que funcione.

Só uma coisa: essas regras para aceitar o tráfego na porta 80, devem ser colocadas antes da drop-an-log-it ou pode ser depois das regras de redirecionamento?

Muito obrigado mesmo!!!

Um abraço.