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11-06-2010, 03:07 PM
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#1
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Member
Registered: Sep 2008
Location: RJ-Brazil
Distribution: Slackware
Posts: 181
Rep:
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Ping, But Don`t Connect!
I`m using an excellent dedicated Server Project called SMS ( SLACKWARE ) and an easy firewall ( EFG ). Unfortunately I don`t understand the reason so I don`t get internet connection using Workstation. I have a Server settings eth0 isp (dhcp) . Eth1 local ethernet and Thomsom Speedtouch V6 modem.
Server:
.get internet connection
.ping workstation
#vi /etc/resolv.conf ( auto dhcp )
# Generated by dhcpcd from eth0
# /etc/resolv.conf.head can replace this line
domain lan
nameserver 192.168.1.254
# /etc/resolv.conf.tail can replace this line
root@server:/etc/rc.d# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
fail2ban-ProFTPD tcp -- anywhere anywhere tcp dpt:ftp
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain fail2ban-ProFTPD (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-SSH (0 references)
target prot opt source destination
RETURN all -- anywhere anywhere
---------
root@server:/etc/rc.d# iptables -t nat -L
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source
-----------
root@server:/etc/rc.d# cat /proc/sys/net/ipv4/ip_forward
1
Worstations ( static ip ) pings are:
ping gateway ( 192.168.2.1) ok!
ping 192.168.2.7 (static ip)ok!
ping 8.8.8.8 out!
ping www.gmail.com out!
#vi /etc/resolv.conf
search maq7.local
nameserver 200.149.55.140
#route -n
192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 192.168.2.1. 0.0.0.0 UG 202 0 0 eth0
And this is my Easy Firewall (EFG). It seems ok!!!
#!/bin/sh
#
# Generated iptables firewall script for the Linux 2.4 kernel
# Script generated by Easy Firewall Generator for IPTables 1.15
# copyright 2002 Timothy Scott Morizot
#
# Redhat chkconfig comments - firewall applied early,
# removed late
# chkconfig: 2345 08 92
# description: This script applies or removes iptables firewall rules
#
# This generator is primarily designed for RedHat installations,
# although it should be adaptable for others.
#
# It can be executed with the typical start and stop arguments.
# If used with stop, it will stop after flushing the firewall.
# The save and restore arguments will save or restore the rules
# from the /etc/sysconfig/iptables file. The save and restore
# arguments are included to preserve compatibility with
# Redhat's or Fedora's init.d script if you prefer to use it.
# Redhat/Fedora installation instructions
#
# 1. Have the system link the iptables init.d startup script into run states
# 2, 3, and 5.
# chkconfig --level 235 iptables on
#
# 2. Save this script and execute it to load the ruleset from this file.
# You may need to run the dos2unix command on it to remove carraige returns.
#
# 3. To have it applied at startup, copy this script to
# /etc/init.d/iptables. It accepts stop, start, save, and restore
# arguments. (You may wish to save the existing one first.)
# Alternatively, if you issue the 'service iptables save' command
# the init.d script should save the rules and reload them at runtime.
#
# 4. For non-Redhat systems (or Redhat systems if you have a problem), you
# may want to append the command to execute this script to rc.local.
# rc.local is typically located in /etc and /etc/rc.d and is usually
# the last thing executed on startup. Simply add /path/to/script/script_name
# on its own line in the rc.local file.
###############################################################################
#
# Local Settings
#
# sysctl location. If set, it will use sysctl to adjust the kernel parameters.
# If this is set to the empty string (or is unset), the use of sysctl
# is disabled.
SYSCTL="/sbin/sysctl -w"
# To echo the value directly to the /proc file instead
# SYSCTL=""
# IPTables Location - adjust if needed
IPT="/sbin/iptables"
IPTS="/sbin/iptables-save"
IPTR="/sbin/iptables-restore"
# Internet Interface
INET_IFACE="eth0"
INET_ADDRESS="192.168.1.1"
# Local Interface Information
LOCAL_IFACE="eth1"
LOCAL_IP="192.168.2.1"
LOCAL_NET="192.168.2.0/24"
LOCAL_BCAST="192.168.2.255"
# Localhost Interface
LO_IFACE="lo"
LO_IP="127.0.0.1"
# Save and Restore arguments handled here
if [ "$1" = "save" ]
then
echo -n "Saving firewall to /etc/sysconfig/iptables ... "
$IPTS > /etc/sysconfig/iptables
echo "done"
exit 0
elif [ "$1" = "restore" ]
then
echo -n "Restoring firewall from /etc/sysconfig/iptables ... "
$IPTR < /etc/sysconfig/iptables
echo "done"
exit 0
fi
###############################################################################
#
# Load Modules
#
echo "Loading kernel modules ..."
# You should uncomment the line below and run it the first time just to
# ensure all kernel module dependencies are OK. There is no need to run
# every time, however.
# /sbin/depmod -a
# Unless you have kernel module auto-loading disabled, you should not
# need to manually load each of these modules. Other than ip_tables,
# ip_conntrack, and some of the optional modules, I've left these
# commented by default. Uncomment if you have any problems or if
# you have disabled module autoload. Note that some modules must
# be loaded by another kernel module.
# core netfilter module
/sbin/modprobe ip_tables
# the stateful connection tracking module
/sbin/modprobe ip_conntrack
# filter table module
# /sbin/modprobe iptable_filter
# mangle table module
# /sbin/modprobe iptable_mangle
# nat table module
# /sbin/modprobe iptable_nat
# LOG target module
# /sbin/modprobe ipt_LOG
# This is used to limit the number of packets per sec/min/hr
# /sbin/modprobe ipt_limit
# masquerade target module
# /sbin/modprobe ipt_MASQUERADE
# filter using owner as part of the match
# /sbin/modprobe ipt_owner
# REJECT target drops the packet and returns an ICMP response.
# The response is configurable. By default, connection refused.
# /sbin/modprobe ipt_REJECT
# This target allows packets to be marked in the mangle table
# /sbin/modprobe ipt_mark
# This target affects the TCP MSS
# /sbin/modprobe ipt_tcpmss
# This match allows multiple ports instead of a single port or range
# /sbin/modprobe multiport
# This match checks against the TCP flags
# /sbin/modprobe ipt_state
# This match catches packets with invalid flags
# /sbin/modprobe ipt_unclean
# The ftp nat module is required for non-PASV ftp support
/sbin/modprobe ip_nat_ftp
# the module for full ftp connection tracking
/sbin/modprobe ip_conntrack_ftp
# the module for full irc connection tracking
/sbin/modprobe ip_conntrack_irc
###############################################################################
#
# Kernel Parameter Configuration
#
# See http://ipsysctl-tutorial.frozentux.n...tml/index.html
# for a detailed tutorial on sysctl and the various settings
# available.
# Required to enable IPv4 forwarding.
# Redhat users can try setting FORWARD_IPV4 in /etc/sysconfig/network to true
# Alternatively, it can be set in /etc/sysctl.conf
if [ "$SYSCTL" = "" ]
then
echo "1" > /proc/sys/net/ipv4/ip_forward
else
$SYSCTL net.ipv4.ip_forward="1"
fi
# This enables dynamic address hacking.
# This may help if you have a dynamic IP address \(e.g. slip, ppp, dhcp\).
#if [ "$SYSCTL" = "" ]
#then
# echo "1" > /proc/sys/net/ipv4/ip_dynaddr
#else
# $SYSCTL net.ipv4.ip_dynaddr="1"
#fi
# This enables SYN flood protection.
# The SYN cookies activation allows your system to accept an unlimited
# number of TCP connections while still trying to give reasonable
# service during a denial of service attack.
if [ "$SYSCTL" = "" ]
then
echo "1" > /proc/sys/net/ipv4/tcp_syncookies
else
$SYSCTL net.ipv4.tcp_syncookies="1"
fi
# This enables source validation by reversed path according to RFC1812.
# In other words, did the response packet originate from the same interface
# through which the source packet was sent? It's recommended for single-homed
# systems and routers on stub networks. Since those are the configurations
# this firewall is designed to support, I turn it on by default.
# Turn it off if you use multiple NICs connected to the same network.
if [ "$SYSCTL" = "" ]
then
echo "1" > /proc/sys/net/ipv4/conf/all/rp_filter
else
$SYSCTL net.ipv4.conf.all.rp_filter="1"
fi
# This option allows a subnet to be firewalled with a single IP address.
# It's used to build a DMZ. Since that's not a focus of this firewall
# script, it's not enabled by default, but is included for reference.
# See: http://www.sjdjweis.com/linux/proxyarp/
#if [ "$SYSCTL" = "" ]
#then
# echo "1" > /proc/sys/net/ipv4/conf/all/proxy_arp
#else
# $SYSCTL net.ipv4.conf.all.proxy_arp="1"
#fi
# The following kernel settings were suggested by Alex Weeks. Thanks!
# This kernel parameter instructs the kernel to ignore all ICMP
# echo requests sent to the broadcast address. This prevents
# a number of smurfs and similar DoS nasty attacks.
if [ "$SYSCTL" = "" ]
then
echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
else
$SYSCTL net.ipv4.icmp_echo_ignore_broadcasts="1"
fi
# This option can be used to accept or refuse source routed
# packets. It is usually on by default, but is generally
# considered a security risk. This option turns it off.
if [ "$SYSCTL" = "" ]
then
echo "0" > /proc/sys/net/ipv4/conf/all/accept_source_route
else
$SYSCTL net.ipv4.conf.all.accept_source_route="0"
fi
# This option can disable ICMP redirects. ICMP redirects
# are generally considered a security risk and shouldn't be
# needed by most systems using this generator.
#if [ "$SYSCTL" = "" ]
#then
# echo "0" > /proc/sys/net/ipv4/conf/all/accept_redirects
#else
# $SYSCTL net.ipv4.conf.all.accept_redirects="0"
#fi
# However, we'll ensure the secure_redirects option is on instead.
# This option accepts only from gateways in the default gateways list.
if [ "$SYSCTL" = "" ]
then
echo "1" > /proc/sys/net/ipv4/conf/all/secure_redirects
else
$SYSCTL net.ipv4.conf.all.secure_redirects="1"
fi
# This option logs packets from impossible addresses.
if [ "$SYSCTL" = "" ]
then
echo "1" > /proc/sys/net/ipv4/conf/all/log_martians
else
$SYSCTL net.ipv4.conf.all.log_martians="1"
fi
###############################################################################
#
# Flush Any Existing Rules or Chains
#
echo "Flushing Tables ..."
# Reset Default Policies
$IPT -P INPUT ACCEPT
$IPT -P FORWARD ACCEPT
$IPT -P OUTPUT ACCEPT
$IPT -t nat -P PREROUTING ACCEPT
$IPT -t nat -P POSTROUTING ACCEPT
$IPT -t nat -P OUTPUT ACCEPT
$IPT -t mangle -P PREROUTING ACCEPT
$IPT -t mangle -P OUTPUT ACCEPT
# Flush all rules
$IPT -F
$IPT -t nat -F
$IPT -t mangle -F
# Erase all non-default chains
$IPT -X
$IPT -t nat -X
$IPT -t mangle -X
if [ "$1" = "stop" ]
then
echo "Firewall completely flushed! Now running with no firewall."
exit 0
fi
###############################################################################
#
# Rules Configuration
#
###############################################################################
#
# Filter Table
#
###############################################################################
# Set Policies
$IPT -P INPUT DROP
$IPT -P OUTPUT DROP
$IPT -P FORWARD DROP
###############################################################################
#
# User-Specified Chains
#
# Create user chains to reduce the number of rules each packet
# must traverse.
echo "Create and populate custom rule chains ..."
# Create a chain to filter INVALID packets
$IPT -N bad_packets
# Create another chain to filter bad tcp packets
$IPT -N bad_tcp_packets
# Create separate chains for icmp, tcp (incoming and outgoing),
# and incoming udp packets.
$IPT -N icmp_packets
# Used for UDP packets inbound from the Internet
$IPT -N udp_inbound
# Used to block outbound UDP services from internal network
# Default to allow all
$IPT -N udp_outbound
# Used to allow inbound services if desired
# Default fail except for established sessions
$IPT -N tcp_inbound
# Used to block outbound services from internal network
# Default to allow all
$IPT -N tcp_outbound
###############################################################################
#
# Populate User Chains
#
# bad_packets chain
#
# Drop packets received on the external interface
# claiming a source of the local network
$IPT -A bad_packets -p ALL -i $INET_IFACE -s $LOCAL_NET -j LOG \
--log-prefix "Illegal source: "
$IPT -A bad_packets -p ALL -i $INET_IFACE -s $LOCAL_NET -j DROP
# Drop INVALID packets immediately
$IPT -A bad_packets -p ALL -m state --state INVALID -j LOG \
--log-prefix "Invalid packet: "
$IPT -A bad_packets -p ALL -m state --state INVALID -j DROP
# Then check the tcp packets for additional problems
$IPT -A bad_packets -p tcp -j bad_tcp_packets
# All good, so return
$IPT -A bad_packets -p ALL -j RETURN
# bad_tcp_packets chain
#
# All tcp packets will traverse this chain.
# Every new connection attempt should begin with
# a syn packet. If it doesn't, it is likely a
# port scan. This drops packets in state
# NEW that are not flagged as syn packets.
# Return to the calling chain if the bad packets originate
# from the local interface. This maintains the approach
# throughout this firewall of a largely trusted internal
# network.
$IPT -A bad_tcp_packets -p tcp -i $LOCAL_IFACE -j RETURN
# However, I originally did apply this filter to the forward chain
# for packets originating from the internal network. While I have
# not conclusively determined its effect, it appears to have the
# interesting side effect of blocking some of the ad systems.
# Apparently some ad systems have the browser initiate a NEW
# connection that is not flagged as a syn packet to retrieve
# the ad image. If you wish to experiment further comment the
# rule above. If you try it, you may also wish to uncomment the
# rule below. It will keep those packets from being logged.
# There are a lot of them.
# $IPT -A bad_tcp_packets -p tcp -i $LOCAL_IFACE ! --syn -m state \
# --state NEW -j DROP
$IPT -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j LOG \
--log-prefix "New not syn: "
$IPT -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j DROP
$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL NONE -j LOG \
--log-prefix "Stealth scan: "
$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL NONE -j DROP
$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL ALL -j LOG \
--log-prefix "Stealth scan: "
$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL ALL -j DROP
$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL FIN,URG,PSH -j LOG \
--log-prefix "Stealth scan: "
$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL FIN,URG,PSH -j DROP
$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j LOG \
--log-prefix "Stealth scan: "
$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP
$IPT -A bad_tcp_packets -p tcp --tcp-flags SYN,RST SYN,RST -j LOG \
--log-prefix "Stealth scan: "
$IPT -A bad_tcp_packets -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
$IPT -A bad_tcp_packets -p tcp --tcp-flags SYN,FIN SYN,FIN -j LOG \
--log-prefix "Stealth scan: "
$IPT -A bad_tcp_packets -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP
# All good, so return
$IPT -A bad_tcp_packets -p tcp -j RETURN
# icmp_packets chain
#
# This chain is for inbound (from the Internet) icmp packets only.
# Type 8 (Echo Request) is not accepted by default
# Enable it if you want remote hosts to be able to reach you.
# 11 (Time Exceeded) is the only one accepted
# that would not already be covered by the established
# connection rule. Applied to INPUT on the external interface.
#
# See: http://www.ee.siue.edu/~rwalden/networking/icmp.html
# for more info on ICMP types.
#
# Note that the stateful settings allow replies to ICMP packets.
# These rules allow new packets of the specified types.
# ICMP packets should fit in a Layer 2 frame, thus they should
# never be fragmented. Fragmented ICMP packets are a typical sign
# of a denial of service attack.
$IPT -A icmp_packets --fragment -p ICMP -j LOG \
--log-prefix "ICMP Fragment: "
$IPT -A icmp_packets --fragment -p ICMP -j DROP
# Echo - uncomment to allow your system to be pinged.
# Uncomment the LOG command if you also want to log PING attempts
#
# $IPT -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j LOG \
# --log-prefix "Ping detected: "
# $IPT -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j ACCEPT
# By default, however, drop pings without logging. Blaster
# and other worms have infected systems blasting pings.
# Comment the line below if you want pings logged, but it
# will likely fill your logs.
$IPT -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j DROP
# Time Exceeded
$IPT -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT
# Not matched, so return so it will be logged
$IPT -A icmp_packets -p ICMP -j RETURN
# TCP & UDP
# Identify ports at:
# http://www.chebucto.ns.ca/~rakerman/port-table.html
# http://www.iana.org/assignments/port-numbers
# udp_inbound chain
#
# This chain describes the inbound UDP packets it will accept.
# It's applied to INPUT on the external or Internet interface.
# Note that the stateful settings allow replies.
# These rules are for new requests.
# It drops netbios packets (windows) immediately without logging.
# Drop netbios calls
# Please note that these rules do not really change the way the firewall
# treats netbios connections. Connections from the localhost and
# internal interface (if one exists) are accepted by default.
# Responses from the Internet to requests initiated by or through
# the firewall are also accepted by default. To get here, the
# packets would have to be part of a new request received by the
# Internet interface. You would have to manually add rules to
# accept these. I added these rules because some network connections,
# such as those via cable modems, tend to be filled with noise from
# unprotected Windows machines. These rules drop those packets
# quickly and without logging them. This prevents them from traversing
# the whole chain and keeps the log from getting cluttered with
# chatter from Windows systems.
$IPT -A udp_inbound -p UDP -s 0/0 --destination-port 137 -j DROP
$IPT -A udp_inbound -p UDP -s 0/0 --destination-port 138 -j DROP
# Ident requests (Port 113) must have a REJECT rule rather than the
# default DROP rule. This is the minimum requirement to avoid
# long delays while connecting. Also see the tcp_inbound rule.
$IPT -A udp_inbound -p UDP -s 0/0 --destination-port 113 -j REJECT
# A more sophisticated configuration could accept the ident requests.
# $IPT -A udp_inbound -p UDP -s 0/0 --destination-port 113 -j ACCEPT
# However, if this is a gateway system that masquerades/nats for internal systems
# and the internal systems wish to chat, a simple changing these rules to
# ACCEPT won't work. The ident daemon on the gateway will need to know how
# to handle the requests. The stock daemon in most linux distributions
# can't do that. oidentd is one package that can.
# See: http://dev.ojnk.net/
# Dynamic Address
# If DHCP, the initial request is a broadcast. The response
# doesn't exactly match the outbound packet. This explicitly
# allow the DHCP ports to alleviate this problem.
# If you receive your dynamic address by a different means, you
# can probably comment this line.
$IPT -A udp_inbound -p UDP -s 0/0 --source-port 67 --destination-port 68 \
-j ACCEPT
# Not matched, so return for logging
$IPT -A udp_inbound -p UDP -j RETURN
# udp_outbound chain
#
# This chain is used with a private network to prevent forwarding for
# UDP requests on specific protocols. Applied to the FORWARD rule from
# the internal network. Ends with an ACCEPT
# No match, so ACCEPT
$IPT -A udp_outbound -p UDP -s 0/0 -j ACCEPT
# tcp_inbound chain
#
# This chain is used to allow inbound connections to the
# system/gateway. Use with care. It defaults to none.
# It's applied on INPUT from the external or Internet interface.
# Ident requests (Port 113) must have a REJECT rule rather than the
# default DROP rule. This is the minimum requirement to avoid
# long delays while connecting. Also see the tcp_inbound rule.
$IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 113 -j REJECT
# A more sophisticated configuration could accept the ident requests.
# $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 113 -j ACCEPT
# However, if this is a gateway system that masquerades/nats for internal systems
# and the internal systems wish to chat, a simple changing these rules to
# ACCEPT won't work. The ident daemon on the gateway will need to know how
# to handle the requests. The stock daemon in most linux distributions
# can't do that. oidentd is one package that can.
# See: http://dev.ojnk.net/
# sshd
$IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 22 -j ACCEPT
# ICQ File Transfers & Other Advanced Features
#
# ICQ supports a number of options beyond simple instant messaging.
# For those to function, the instant messaging system must allow
# new connections initiated from remote systems. This option will
# open a specified port range on the firewalled system. The ICQ client
# on the firewalled system must also be configured to use the specified
# port range.
$IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 5000:5100 -j ACCEPT
# MSN Messenger File Transfers
#
# Messenger supports file transfers. For transfers initiated by
# remote systems to function, the system must allow
# new connections initiated from remote systems a specific port range.
# This option defaults to the port range 6891 through 6900.
# Unless the MSN Messenger client can be configured to specify any
# port range, don't change the default.
$IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 6891:6900 -j ACCEPT
# Not matched, so return so it will be logged
$IPT -A tcp_inbound -p TCP -j RETURN
# tcp_outbound chain
#
# This chain is used with a private network to prevent forwarding for
# requests on specific protocols. Applied to the FORWARD rule from
# the internal network. Ends with an ACCEPT
# No match, so ACCEPT
$IPT -A tcp_outbound -p TCP -s 0/0 -j ACCEPT
###############################################################################
#
# INPUT Chain
#
echo "Process INPUT chain ..."
# Allow all on localhost interface
$IPT -A INPUT -p ALL -i $LO_IFACE -j ACCEPT
# Drop bad packets
$IPT -A INPUT -p ALL -j bad_packets
# DOCSIS compliant cable modems
# Some DOCSIS compliant cable modems send IGMP multicasts to find
# connected PCs. The multicast packets have the destination address
# 224.0.0.1. You can accept them. If you choose to do so,
# Uncomment the rule to ACCEPT them and comment the rule to DROP
# them The firewall will drop them here by default to avoid
# cluttering the log. The firewall will drop all multicasts
# to the entire subnet (224.0.0.1) by default. To only affect
# IGMP multicasts, change '-p ALL' to '-p 2'. Of course,
# if they aren't accepted elsewhere, it will only ensure that
# multicasts on other protocols are logged.
# Drop them without logging.
$IPT -A INPUT -p ALL -d 224.0.0.1 -j DROP
# The rule to accept the packets.
# $IPT -A INPUT -p ALL -d 224.0.0.1 -j ACCEPT
# Rules for the private network (accessing gateway system itself)
$IPT -A INPUT -p ALL -i $LOCAL_IFACE -s $LOCAL_NET -j ACCEPT
$IPT -A INPUT -p ALL -i $LOCAL_IFACE -d $LOCAL_BCAST -j ACCEPT
# Inbound Internet Packet Rules
# Accept Established Connections
$IPT -A INPUT -p ALL -i $INET_IFACE -m state --state ESTABLISHED,RELATED \
-j ACCEPT
# Route the rest to the appropriate user chain
$IPT -A INPUT -p TCP -i $INET_IFACE -j tcp_inbound
$IPT -A INPUT -p UDP -i $INET_IFACE -j udp_inbound
$IPT -A INPUT -p ICMP -i $INET_IFACE -j icmp_packets
# Drop without logging broadcasts that get this far.
# Cuts down on log clutter.
# Comment this line if testing new rules that impact
# broadcast protocols.
$IPT -A INPUT -m pkttype --pkt-type broadcast -j DROP
# Log packets that still don't match
$IPT -A INPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-prefix "INPUT packet died: "
###############################################################################
#
# FORWARD Chain
#
echo "Process FORWARD chain ..."
# Used if forwarding for a private network
# Drop bad packets
$IPT -A FORWARD -p ALL -j bad_packets
# Accept TCP packets we want to forward from internal sources
$IPT -A FORWARD -p tcp -i $LOCAL_IFACE -j tcp_outbound
# Accept UDP packets we want to forward from internal sources
$IPT -A FORWARD -p udp -i $LOCAL_IFACE -j udp_outbound
# If not blocked, accept any other packets from the internal interface
$IPT -A FORWARD -p ALL -i $LOCAL_IFACE -j ACCEPT
# Deal with responses from the internet
$IPT -A FORWARD -i $INET_IFACE -m state --state ESTABLISHED,RELATED \
-j ACCEPT
# Log packets that still don't match
$IPT -A FORWARD -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-prefix "FORWARD packet died: "
###############################################################################
#
# OUTPUT Chain
#
echo "Process OUTPUT chain ..."
# Generally trust the firewall on output
# However, invalid icmp packets need to be dropped
# to prevent a possible exploit.
$IPT -A OUTPUT -m state -p icmp --state INVALID -j DROP
# Localhost
$IPT -A OUTPUT -p ALL -s $LO_IP -j ACCEPT
$IPT -A OUTPUT -p ALL -o $LO_IFACE -j ACCEPT
# To internal network
$IPT -A OUTPUT -p ALL -s $LOCAL_IP -j ACCEPT
$IPT -A OUTPUT -p ALL -o $LOCAL_IFACE -j ACCEPT
# To internet
$IPT -A OUTPUT -p ALL -o $INET_IFACE -j ACCEPT
# Log packets that still don't match
$IPT -A OUTPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-prefix "OUTPUT packet died: "
###############################################################################
#
# nat table
#
###############################################################################
# The nat table is where network address translation occurs if there
# is a private network. If the gateway is connected to the Internet
# with a static IP, snat is used. If the gateway has a dynamic address,
# masquerade must be used instead. There is more overhead associated
# with masquerade, so snat is better when it can be used.
# The nat table has a builtin chain, PREROUTING, for dnat and redirects.
# Another, POSTROUTING, handles snat and masquerade.
echo "Load rules for nat table ..."
###############################################################################
#
# PREROUTING chain
#
###############################################################################
#
# POSTROUTING chain
#
$IPT -t nat -A POSTROUTING -o $INET_IFACE -j MASQUERADE
###############################################################################
#
# mangle table
#
###############################################################################
# The mangle table is used to alter packets. It can alter or mangle them in
# several ways. For the purposes of this generator, we only use its ability
# to alter the TTL in packets. However, it can be used to set netfilter
# mark values on specific packets. Those marks could then be used in another
# table like filter, to limit activities associated with a specific host, for
# instance. The TOS target can be used to set the Type of Service field in
# the IP header. Note that the TTL target might not be included in the
# distribution on your system. If it is not and you require it, you will
# have to add it. That may require that you build from source.
echo "Load rules for mangle table ..."
----------------------------------------------------------
What can be a way to corret it and get workstation internet connection?
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11-07-2010, 03:52 AM
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#2
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Senior Member
Registered: Jul 2007
Distribution: Gentoo
Posts: 2,125
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It looks like you may have an address discrepancy or conflict in your settings. See the following (snipped) entries:
Quote:
nameserver 192.168.1.254
Worstations ( static ip ) pings are:
ping gateway ( 192.168.2.1) ok!
ping 192.168.2.7 (static ip)ok!
#route -n
192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
0.0.0.0 192.168.2.1. 0.0.0.0 UG 202 0 0 eth0
# Internet Interface
INET_IFACE="eth0"
INET_ADDRESS="192.168.1.1"
# Local Interface Information
LOCAL_IFACE="eth1"
LOCAL_IP="192.168.2.1"
LOCAL_NET="192.168.2.0/24"
LOCAL_BCAST="192.168.2.255"
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Basically, you seem to have two subnets running: 192.168.2.0/24 and 192.168.1.0/24 and it looks like you have attempted to 'bridge' them by adding a route entry. I am not confident that will work. There would be several ways to fix this. Three off the top of my head are: 1 - change everything to a 192.168.1.x range, 2 - use a router between the two subnets, 3 - change the mask to a different value, such as /23 which would give you more hosts on one subnet.
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