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
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
#!/bin/bash
# (using bashism: arrays)
service="${PWD##*/}"
rundir="/var/run/service/$service"
user=root
extif=if
ext_open_tcp="21 22 80" # space-separated
# Make ourself one-shot
sv o .
# Debug
#date '+%Y-%m-%d %H:%M:%S' >>"$0.log"
### filter This is the default table (if no -t option is passed). It contains
### the built-in chains INPUT (for packets coming into the box itself),
### FORWARD (for packets being routed through the box), and OUTPUT (for
### locally-generated packets).
###
### nat This table is consulted when a packet that creates a new connection
### is encountered. It consists of three built-ins: PREROUTING (for
### altering packets as soon as they come in), OUTPUT (for altering
### locally-generated packets before routing), and POSTROUTING (for
### altering packets as they are about to go out).
###
### mangle It had two built-in chains: PREROUTING (for altering incoming
### packets before routing) and OUTPUT (for altering locally-generated
### packets before routing). Recently three other built-in
### chains are added: INPUT (for packets coming into the box
### itself), FORWARD (for altering packets being routed through the
### box), and POSTROUTING (for altering packets as they are about to go
### out).
###
### ...iface... ...iface...
### | ^
### v |
### -mangle,NAT- -mangle,filter- -mangle,NAT--
### |PREROUTING|-->[Routing]-->|FORWARD |-->|POSTROUTING|
### ------------ | ^ --------------- -------------
### | | ^
### | +--if NATed------------+ |
### v | |
### -mangle,filter- -mangle,NAT,filter-
### |INPUT | +->[Routing]->|OUTPUT |
### --------------- | -------------------
### | |
### v |
### ... Local Process...
doit() {
echo "# $*"
"$@"
}
#exec >/dev/null
exec >"$0.out"
exec 2>&1
exec </dev/null
umask 077
# Make sure rundir/ exists
mkdir -p "$rundir" 2>/dev/null
chown -R "$user": "$rundir"
chmod -R a=rX "$rundir"
rm -rf rundir 2>/dev/null
ln -s "$rundir" rundir
# Timestamping
date '+%Y-%m-%d %H:%M:%S'
echo; echo "* Reading IP config"
cfg=-1
# static cfg dhcp,zeroconf etc
for ipconf in conf/*.ipconf "$rundir"/*.ipconf; do
if test -f "$ipconf"; then
echo "+ $ipconf"
. "$ipconf"
fi
done
echo; echo "* Configuring hardware"
#doit ethtool -s if autoneg off speed 100 duplex full
#doit ethtool -K if rx off tx off sg off tso off
echo; echo "* Resetting address and routing info"
doit ip a f dev lo
i=0; while test "${if[$i]}"; do
doit ip a f dev "${if[$i]}"
doit ip r f dev "${if[$i]}" root 0/0
let i++; done
echo; echo "* Configuring addresses"
doit ip a a dev lo 127.0.0.1/8 scope host
doit ip a a dev lo ::1/128 scope host
i=0; while test "${if[$i]}"; do
if test "${ipmask[$i]}"; then
doit ip a a dev "${if[$i]}" "${ipmask[$i]}" brd +
doit ip l set dev "${if[$i]}" up
fi
let i++; done
echo; echo "* Configuring routes"
i=0; while test "${if[$i]}"; do
if test "${net[$i]}" && test "${gw[$i]}"; then
doit ip r a "${net[$i]}" via "${gw[$i]}"
fi
let i++; done
echo; echo "* Recreating /etc/* files reflecting new network configuration:"
for i in etc/*; do
n=`basename "$i"`
echo "+ $n"
(. "$i") >"/etc/$n"
chmod 644 "/etc/$n"
done
# Usage: new_chain <chain> [<table>]
new_chain() {
local t=""
test x"$2" != x"" && t="-t $2"
doit iptables $t -N $1
ipt="iptables $t -A $1"
}
echo; echo "* Reset iptables"
doit iptables --flush
doit iptables --delete-chain
doit iptables --zero
doit iptables -t nat --flush
doit iptables -t nat --delete-chain
doit iptables -t nat --zero
doit iptables -t mangle --flush
doit iptables -t mangle --delete-chain
doit iptables -t mangle --zero
echo; echo "* Configure iptables"
doit modprobe nf_nat_ftp
doit modprobe nf_nat_tftp
doit modprobe nf_conntrack_ftp
doit modprobe nf_conntrack_tftp
# *** nat ***
# INCOMING TRAFFIC
ipt="iptables -t nat -A PREROUTING"
# nothing here
# LOCALLY ORIGINATED TRAFFIC
ipt="iptables -t nat -A OUTPUT"
# nothing here
# OUTGOING TRAFFIC
ipt="iptables -t nat -A POSTROUTING"
# Masquerade boxes on my private net
doit $ipt -s 192.168.0.0/24 -o $extif -j MASQUERADE
# *** mangle ***
### DEBUG
### ipt="iptables -t mangle -A PREROUTING"
### doit $ipt -s 192.168.0.0/24 -j RETURN
### ipt="iptables -t mangle -A FORWARD"
### doit $ipt -s 192.168.0.0/24 -j RETURN
### ipt="iptables -t mangle -A POSTROUTING"
### doit $ipt -s 192.168.0.0/24 -j RETURN
# nothing here
# *** filter ***
#
new_chain iext filter
#doit $ipt -s 203.177.104.72 -j DROP # Some idiot probes my ssh
#doit $ipt -d 203.177.104.72 -j DROP # Some idiot probes my ssh
doit $ipt -m state --state ESTABLISHED,RELATED -j RETURN # FTP data etc is ok
if test "$ext_open_tcp"; then
portlist="${ext_open_tcp// /,}"
doit $ipt -p tcp -m multiport --dports $portlist -j RETURN
fi
doit $ipt -p tcp -j REJECT # Anything else isn't ok. REJECT = irc opens faster
# (it probes proxy ports, DROP will incur timeout delays)
ipt="iptables -t filter -A INPUT"
doit $ipt -i $extif -j iext
echo; echo "* Enabling forwarding"
echo 1 >/proc/sys/net/ipv4/ip_forward
echo "/proc/sys/net/ipv4/ip_forward: `cat /proc/sys/net/ipv4/ip_forward`"
# Signal everybody that firewall is up
date '+%Y-%m-%d %H:%M:%S' >"$rundir/up"
# Ok, spew out gobs of info and disable ourself
echo; echo "* IP:"
ip a l
echo; echo "* Routing:"
ip r l
echo; echo "* Firewall:"
{
echo '---FILTER--';
iptables -v -L -x -n;
echo '---NAT-----';
iptables -t nat -v -L -x -n;
echo '---MANGLE--';
iptables -t mangle -v -L -x -n;
} \
| grep -v '^$' | grep -Fv 'bytes target'
echo
echo "* End of firewall configuration"
|
