Tag Archive for 'IPv6 security'

IPv6 and ip6tables

Published on July 24, 2010 21:00 Tags: , , , , .

I describe a little bit how to secure your IPv6 server with Netfilter-ip6tables.

Refer to the IANA message types.

My example IPv6 firewall script:

Earlier predefined variables:

1
2

IPT6="/sbin/ip6tables"
OUTER="eth0"
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52

# Clean old IPv6 firewall
$IPT6 -F
$IPT6 -X
 
# Clean old iptables v6 tables
for chain in mangle filter
do
    $IPT6 -t $chain -F
    $IPT6 -t $chain -X
done
 
# Set IPv6 default chains
$IPT6 -P INPUT DROP 
$IPT6 -P FORWARD DROP
$IPT6 -P OUTPUT ACCEPT
 
$IPT6 -A INPUT -i $OUTER -m state --state RELATED,ESTABLISHED -j ACCEPT
 
$IPT6 -A INPUT -i lo -j ACCEPT
 
# Allow SSH from Hetzner IPv6-NET
$IPT6 -A INPUT -s 2001:470:1f0b:1604::/64 -i $OUTER -p tcp -m tcp --dport 22 -j ACCEPT
 
# Allow SSH from Home IPv6-NET
$IPT6 -A INPUT -s 2001:470:1f0b:1514::/64 -i $OUTER -p tcp -m tcp --dport 22 -j ACCEPT
 
# Allow ICMP from Hetzner IPv6-NET
$IPT6 -A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 128 -m limit --limit 15/sec -s 2001:470:1f0b:1604::/64 -j ACCEPT
$IPT6 -A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 129 -m limit --limit 15/sec -s 2001:470:1f0b:1604::/64 -j ACCEPT
 
# Allow ICMP from Home IPv6-NET
$IPT6 -A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 128 -m limit --limit 15/sec -s 2001:470:1f0b:1514::/64 -j ACCEPT
$IPT6 -A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 129 -m limit --limit 15/sec -s 2001:470:1f0b:1514::/64 -j ACCEPT
 
$IPT6 -A INPUT -i $OUTER -p tcp -m tcp --dport 25 -j ACCEPT     # SMTP  
$IPT6 -A INPUT -i $OUTER -p tcp -m tcp --dport 53 -j ACCEPT     # DNS via TCP
$IPT6 -A INPUT -i $OUTER -p udp -m udp --dport 53 -j ACCEPT     # DNS via UDP
$IPT6 -A INPUT -i $OUTER -p tcp -m tcp --dport 80 -j ACCEPT     # HTTP
$IPT6 -A INPUT -i $OUTER -p tcp -m tcp --dport 110 -j ACCEPT    # POP3
$IPT6 -A INPUT -i $OUTER -p tcp -m tcp --dport 143 -j ACCEPT    # IMAP
$IPT6 -A INPUT -i $OUTER -p tcp -m tcp -s 2001:470:1f0b:1604::3/64 --dport 4949 -j ACCEPT
 
$IPT6 -A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 133 -m hl --hl-eq 255 -j ACCEPT
$IPT6 -A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 134 -m hl --hl-eq 255 -j ACCEPT
$IPT6 -A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 135 -m hl --hl-eq 255 -j ACCEPT
$IPT6 -A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 136 -m hl --hl-eq 255 -j ACCEPT
$IPT6 -A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 137 -m hl --hl-eq 255 -j ACCEPT
 
$IPT6 -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
 
# Example of logging
$IPT6 -A INPUT -p ipv6-icmp -j LOG --log-prefix "Dropped ICMPv6 Packets "

Nmap IPv6 addresses

Published on July 24, 2010 20:17 Tags: , .

When conducting a penetration test against an IPv6 enabled system, the first step is to determine what services are accessible over IPv6. Then you should close unnecessary ports for third persons ; for example SSH.

Consider the Nmap results below

Easy portscan syntax:

1

root@acer:~# nmap -6 2001:470:1f0b:1604::3

A little bit complexer syntax without DNS resolution, and a predefined port range:

1

root@acer:~# nmap -6 -p1-10000 -n 2001:470:1f0b:1604::3 -PN

Output:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

Starting Nmap 5.00 ( http://nmap.org ) at 2010-07-24 19:16 CEST
Interesting ports on 2001:470:1f0b:1604::3:
Not shown: 9989 closed ports
PORT    STATE    SERVICE
21/tcp  open     ftp
22/tcp  open     ssh
53/tcp  open     domain
80/tcp  open     http
110/tcp open     pop3
143/tcp open     imap
443/tcp open     https
623/tcp filtered unknown
664/tcp filtered secure-aux-bus
993/tcp open     imaps
995/tcp open     pop3s