Chris on 18 Nov 2003 17:38:03 -0500


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[PLUG] IPTables Help..




Can anyone tell me what im doing wrong? All in_bound port filtering
works like a charm coming in.

Problem lies on the Output.  Once DROPS are applied the machine can no
longer make any outbound connections.
Even after   any / any / all accept is applied. Any iptables gurus want
to help me with this?


root@mysql:/etc/firewall# telnet 64.115.34.114 22
Trying 64.115.34.114...
Connected to 64.115.34.114.
Escape character is '^]'.
SSH-2.0-3.2.0 SSH Secure Shell (non-commercial)
^]
telnet> quit
Connection closed.
root@mysql:/etc/firewall# ./eth0 
Flush IPTables:  ..done
Setting ICMP Rules:  ..done
Setting INPUT Rules:  ..done
Setting OUTPUT Rules:  ..done
root@mysql:/etc/firewall# telnet 64.115.34.114 22
Trying 64.115.34.114...
telnet: Unable to connect to remote host: Connection timed out
root@mysql:/etc/firewall# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     tcp  --  anywhere             mysql.jynx.net     tcp dpt:85 
ACCEPT     tcp  --  user216-178-70-3.netcarrier.net  mysql.jynx.net
tcp dpt:ssh 
ACCEPT     tcp  --  pcp01341770pcs.wilog301.pa.comcast.net
mysql.jynx.net     tcp dpt:ssh 
ACCEPT     udp  --  anywhere             ns3.jynx.net       udp
dpt:domain 
ACCEPT     udp  --  anywhere             ns3.jynx.net       udp
spt:domain 
ACCEPT     tcp  --  10.10.10.0/24        10.0.0.2           tcp
dpts:tcpmux:65535 
ACCEPT     udp  --  10.10.10.0/24        10.0.0.2           udp
dpts:1:65535 
DROP       tcp  --  anywhere             mysql.jynx.net     tcp
dpts:tcpmux:65535 
DROP       udp  --  anywhere             mysql.jynx.net     udp
dpts:1:65535 
DROP       tcp  --  anywhere             ns3.jynx.net       tcp
dpts:tcpmux:65535 
DROP       udp  --  anywhere             ns3.jynx.net       udp
dpts:1:65535 

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  localhost            anywhere           
ACCEPT     all  --  anywhere             anywhere           





#!/bin/sh
IPT="/usr/local/sbin/iptables"
EX_IP="64.115.34.115"
IN_IP="10.0.0.2"
AL_IP="64.115.34.116"
IN_NET="10.10.10.0/24"

echo -n "Flush IPTables: "
$IPT -P INPUT ACCEPT
$IPT -P FORWARD ACCEPT
$IPT -P OUTPUT ACCEPT

# Flush it.
#$IPT -F

        echo " ..done"


                echo -n "Setting ICMP Rules: "
#$IPT -N icmp_packets
#$IPT -A icmp_packets --fragment -p ICMP -j LOG --log-prefix "ICMP
Fragment: "
#$IPT -A icmp_packets --fragment -p ICMP -j DROP
#$IPT -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT
#$IPT -A icmp_packets -p ICMP -j RETURN
                echo " ..done"


        echo -n "Setting INPUT Rules: "
# Webmin
$IPT -A INPUT -p tcp -s 0/0 -d $EX_IP -i eth0 --dport 85 -j ACCEPT
# SSH
$IPT -A INPUT -p tcp -s 216.178.70.3 -d $EX_IP -i eth0 --dport 22 -j
ACCEPT
$IPT -A INPUT -p tcp -s 68.81.114.30 -d $EX_IP -i eth0 --dport 22 -j
ACCEPT
# DNS
$IPT -A INPUT -p udp -s 0/0 -d $AL_IP -i eth0 --dport 53 -j ACCEPT
# DNS
$IPT -A INPUT -p udp -s 0/0 -d $AL_IP -i eth0 --source-port 53 -j ACCEPT
# Internal
$IPT -A INPUT -p tcp -s $IN_NET -d $IN_IP -i eth1 --dport 1:65535 -j
ACCEPT
# Internal
$IPT -A INPUT -p udp -s $IN_NET -d $IN_IP -i eth1 --dport 1:65535 -j
ACCEPT
# Allow Inside Out

        echo " ..done"

                echo -n "Setting OUTPUT Rules: "
        echo " "
$IPT -A OUTPUT -p ALL -s 127.0.0.1 -j ACCEPT
$IPT -A OUTPUT -p ALL -o lo -j ACCEPT
$IPT -A OUTPUT -o eth0 -j ACCEPT


$IPT -A INPUT -p tcp -s 0/0 -d $EX_IP -i eth0 --dport 1:65535 -j DROP
$IPT -A INPUT -p udp -s 0/0 -d $EX_IP -i eth0 --dport 1:65535 -j DROP

$IPT -A INPUT -p tcp -s 0/0 -d $AL_IP -i eth0 --dport 1:65535 -j DROP
$IPT -A INPUT -p udp -s 0/0 -d $AL_IP -i eth0 --dport 1:65535 -j DROP


                echo " ..done"

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