Hello,
I'm currently struggling with an iptables script to make it allow ssh connections from anywhere. This script, I found on the internet: (
http://www.ibiblio.org/pub/Linux/doc...NG-RC.FIREWALL)
When I installed it, I was completely new to iptables but the information and explanations on the site convinced me that it's an ok firewall. Meanwhile, I tried to understand iptables better because it looks important enough to have a secured pc.
So I was looking around and puzzled the following line:
$IPTABLES -A INPUT -p tcp -s $UNIVERSE --dport 22 -m state --state NEW -j ACCEPT
But still, ssh only works from the lan as it always did. I have a rootshell.be acount from which I did a test and it still don't work from the internet. (I am allowed to use ssh from this acount)
To be complete, here's the script I took from the internet with the extra line I added to try to get ssh to work.
FWVER=0.80s
echo -e "\nLoading rc.firewall - version $FWVER..\n"
IPTABLES=/sbin/iptables
LSMOD=/sbin/lsmod
DEPMOD=/sbin/depmod
MODPROBE=/sbin/modprobe
GREP=/bin/grep
AWK=/usr/bin/awk
SED=/bin/sed
IFCONFIG=/sbin/ifconfig
EXTIF="eth1"
INTIF="eth0"
echo " External Interface: $EXTIF"
echo " Internal Interface: $INTIF"
echo " ---"
EXTIP="`$IFCONFIG $EXTIF | $AWK \
/$EXTIF/'{next}//{split($0,a,":");split(a[2],a," ");print a[1];exit}'`"
echo " External IP: $EXTIP"
echo " ---"
INTNET="192.168.0.0/24"
INTIP="192.168.0.1/24"
echo " Internal Network: $INTNET"
echo " Internal IP: $INTIP"
echo " ---"
UNIVERSE="0.0.0.0/0"
echo " - Verifying that all kernel modules are ok"
$DEPMOD -a
echo -en " Loading kernel modules: "
echo -en "ip_tables, "
if [ -z "` $LSMOD | $GREP ip_tables | $AWK {'print $1'} `" ]; then
$MODPROBE ip_tables
fi
echo -en "ip_conntrack, "
if [ -z "` $LSMOD | $GREP ip_conntrack | $AWK {'print $1'} `" ]; then
$MODPROBE ip_conntrack
fi
echo -e "ip_conntrack_ftp, "
if [ -z "` $LSMOD | $GREP ip_conntrack_ftp | $AWK {'print $1'} `" ]; then
$MODPROBE ip_conntrack_ftp
fi
echo -en "iptable_nat, "
if [ -z "` $LSMOD | $GREP iptable_nat | $AWK {'print $1'} `" ]; then
$MODPROBE iptable_nat
fi
echo -e "ip_nat_ftp"
if [ -z "` $LSMOD | $GREP ip_nat_ftp | $AWK {'print $1'} `" ]; then
$MODPROBE ip_nat_ftp
fi
echo " ---"
echo " Enabling forwarding.."
echo "1" > /proc/sys/net/ipv4/ip_forward
echo " Enabling DynamicAddr.."
echo "1" > /proc/sys/net/ipv4/ip_dynaddr
echo " ---"
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
$IPTABLES -F -t nat
if [ -n "`$IPTABLES -L | $GREP drop-and-log-it`" ]; then
$IPTABLES -F drop-and-log-it
fi
$IPTABLES -X
$IPTABLES -Z
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 REJECT
echo -e "\n - Loading INPUT rulesets"
$IPTABLES -A INPUT -i lo -s $UNIVERSE -d $UNIVERSE -j ACCEPT
$IPTABLES -A INPUT -i $INTIF -s $INTNET -d $UNIVERSE -j ACCEPT
$IPTABLES -A INPUT -i $EXTIF -s $INTNET -d $UNIVERSE -j drop-and-log-it
#line added by Lieven on 11th may 2004 to try to allow ssh traffic from anywhere
$IPTABLES -A INPUT -p tcp -s $UNIVERSE --dport 22 -m state --state NEW -j ACCEPT
#end try-and-error line
$IPTABLES -A INPUT -i $EXTIF -s $UNIVERSE -d $EXTIP -m state --state \
ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A INPUT -s $UNIVERSE -d $UNIVERSE -j drop-and-log-it
echo -e " - Loading OUTPUT rulesets"
$IPTABLES -A OUTPUT -o lo -s $UNIVERSE -d $UNIVERSE -j ACCEPT
$IPTABLES -A OUTPUT -o $INTIF -s $EXTIP -d $INTNET -j ACCEPT
$IPTABLES -A OUTPUT -o $INTIF -s $INTIP -d $INTNET -j ACCEPT
$IPTABLES -A OUTPUT -o $EXTIF -s $UNIVERSE -d $INTNET -j drop-and-log-it
$IPTABLES -A OUTPUT -o $EXTIF -s $EXTIP -d $UNIVERSE -j ACCEPT
$IPTABLES -A OUTPUT -s $UNIVERSE -d $UNIVERSE -j drop-and-log-it
echo -e " - Loading FORWARD rulesets"
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
$IPTABLES -A FORWARD -j drop-and-log-it
echo " - NAT: Enabling SNAT (MASQUERADE) functionality on $EXTIF"
$IPTABLES -t nat -A POSTROUTING -o $EXTIF -j SNAT --to $EXTIP
If anybody can give me some advice on this, all help is greatly appreciated.
kind regards,
Lieven
