Forum général.général OpenVPN + iptables

2

20

juin

2013

Je lutte comme une merde pour arriver à mes fins, à savoir faire passer seulement une partie du trafic réseau via le VPN selon le protocole. Dans un premier temps je voudrais faire passer http et https via le VPN et le reste « normalement », hors VPN.

Voici les règles d'iptables qui me semblent importantes dans mon cas (je mets le script qui configure iptables en entier à la fin de ce post)

 $IPTABLES -t mangle -A PREROUTING -j CONNMARK --restore-mark
 $IPTABLES -t mangle -A OUTPUT -j CONNMARK --restore-mark
 $IPTABLES -t mangle -A OUTPUT -p tcp -m tcp -m multiport --dports 80,443 -m state --state NEW -j MARK --set-mark 1
 $IPTABLES -t mangle -A OUTPUT -p tcp -m tcp -m multiport --dports 80,443 -m state --state NEW -j CONNMARK --save-mark

J'ai ajouté l'option route-nopull à la configuration de mon client OpenVPN.

Avant de lancer le VPN j'ai ça :

# ip route
default via 192.168.0.1 dev eth0 
192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.11

Une fois le VPN démarré j'ai ça :

# ip route
default via 192.168.0.1 dev eth0 
10.200.0.0/22 dev tun0 proto kernel scope link src 10.200.3.45 
192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.11

Et une interface tun0 qui ressemble à ça :

tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 
 inet adr:10.200.3.45 P-t-P:10.200.3.45 Masque:255.255.252.0
 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
 RX packets:0 errors:0 dropped:0 overruns:0 frame:0
 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 lg file transmission:100 
 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

J'ai ajouté une table de routage :

# cat /etc/iproute2/rt_tables 
100 vpn

Puis j'ajoute une route par défaut à cette table :

# ip route add default via 10.200.3.45 table vpn
# ip route list table vpn
default via 10.200.3.45 dev tun0 

Ensuite j'ajoute une règle pour dire que les paquets marqués "1" doivent utiliser la table de routage "vpn" :

# ip rule add fwmark 1 table vpn
# ip rule list
0: from all lookup local 
32765: from all fwmark 0x1 lookup vpn 
32766: from all lookup main 
32767: from all lookup default

Voilà, je pensais que c'était bon mais non. Quand je charge une page oueb les paquets ne passent pas par le VPN et pire encore, visiblement ça plante le démon OpenVPN :

# service openvpn status
[FAIL] VPN 'hma' is not running ... failed!

Voilà. J'espère qu'un as du réseau passera par là, qu'il pourra (s'il est pas mort de rire…) m'aider à trouver ce que je fais mal.

Voici le script (généré par Firewall Builder) qui se charge de paramétrer iptables :

#!/bin/sh 
FWBDEBUG=""
PATH="/sbin:/usr/sbin:/bin:/usr/bin:${PATH}"
export PATH
LSMOD="/sbin/lsmod"
MODPROBE="/sbin/modprobe"
IPTABLES="/sbin/iptables"
IP6TABLES="/sbin/ip6tables"
IPTABLES_RESTORE="/sbin/iptables-restore"
IP6TABLES_RESTORE="/sbin/ip6tables-restore"
IP="/sbin/ip"
IFCONFIG="/sbin/ifconfig"
VCONFIG="/sbin/vconfig"
BRCTL="/sbin/brctl"
IFENSLAVE="/sbin/ifenslave"
IPSET="/usr/sbin/ipset"
LOGGER="/usr/bin/logger"
log() {
 echo "1ドル"
 which "$LOGGER" >/dev/null 2>&1 && $LOGGER -p info "1ドル"
}
getInterfaceVarName() {
 echo 1ドル | sed 's/\./_/'
}
getaddr_internal() {
 dev=1ドル
 name=2ドル
 af=3ドル
 L=$($IP $af addr show dev $dev | sed -n '/inet/{s!.*inet6* !!;s!/.*!!p}' | sed 's/peer.*//')
 test -z "$L" && { 
 eval "$name=''"
 return
 }
 eval "${name}_list=\"$L\"" 
}
getnet_internal() {
 dev=1ドル
 name=2ドル
 af=3ドル
 L=$($IP route list proto kernel | grep $dev | grep -v default | sed 's! .*$!!')
 test -z "$L" && { 
 eval "$name=''"
 return
 }
 eval "${name}_list=\"$L\"" 
}
getaddr() {
 getaddr_internal 1ドル 2ドル "-4"
}
getaddr6() {
 getaddr_internal 1ドル 2ドル "-6"
}
getnet() {
 getnet_internal 1ドル 2ドル "-4"
}
getnet6() {
 getnet_internal 1ドル 2ドル "-6"
}
# function getinterfaces is used to process wildcard interfaces
getinterfaces() {
 NAME=1ドル
 $IP link show | grep ": $NAME" | while read L; do
OIFS=$IFS
 IFS=" :"
 set $L
 IFS=$OIFS
 echo 2ドル
 done
}
diff_intf() {
 func=1ドル
 list1=2ドル
 list2=3ドル
 cmd=4ドル
 for intf in $list1
 do
echo $list2 | grep -q $intf || {
 # $vlan is absent in list 2
 $func $intf $cmd
 }
 done
}
find_program() {
 PGM=1ドル
 which $PGM >/dev/null 2>&1 || {
 echo "\"$PGM\" not found"
 exit 1
 }
}
check_tools() {
 find_program which
 find_program $IPTABLES 
 find_program $MODPROBE 
 find_program $IP 
}
reset_iptables_v4() {
 $IPTABLES -P OUTPUT DROP
 $IPTABLES -P INPUT DROP
 $IPTABLES -P FORWARD DROP
cat /proc/net/ip_tables_names | while read table; do
 $IPTABLES -t $table -L -n | while read c chain rest; do
 if test "X$c" = "XChain" ; then
 $IPTABLES -t $table -F $chain
 fi
 done
 $IPTABLES -t $table -X
done
}
reset_iptables_v6() {
 $IP6TABLES -P OUTPUT DROP
 $IP6TABLES -P INPUT DROP
 $IP6TABLES -P FORWARD DROP
cat /proc/net/ip6_tables_names | while read table; do
 $IP6TABLES -t $table -L -n | while read c chain rest; do
 if test "X$c" = "XChain" ; then
 $IP6TABLES -t $table -F $chain
 fi
 done
 $IP6TABLES -t $table -X
done
}
P2P_INTERFACE_WARNING=""
missing_address() {
 address=1ドル
 cmd=2ドル
 oldIFS=$IFS
 IFS="@"
 set $address
 addr=1ドル
 interface=2ドル
 IFS=$oldIFS
 $IP addr show dev $interface | grep -q POINTOPOINT && {
 test -z "$P2P_INTERFACE_WARNING" && echo "Warning: Can not update address of interface $interface. fwbuilder can not manage addresses of point-to-point interfaces yet"
 P2P_INTERFACE_WARNING="yes"
 return
 }
 test "$cmd" = "add" && {
 echo "# Adding ip address: $interface $addr"
 echo $addr | grep -q ':' && {
 $FWBDEBUG $IP addr $cmd $addr dev $interface
 } || {
 $FWBDEBUG $IP addr $cmd $addr broadcast + dev $interface
 }
 }
 test "$cmd" = "del" && {
 echo "# Removing ip address: $interface $addr"
 $FWBDEBUG $IP addr $cmd $addr dev $interface || exit 1
 }
 $FWBDEBUG $IP link set $interface up
}
list_addresses_by_scope() {
 interface=1ドル
 scope=2ドル
 ignore_list=3ドル
 $IP addr ls dev $interface | \
 awk -v IGNORED="$ignore_list" -v SCOPE="$scope" \
 'BEGIN {
 split(IGNORED,ignored_arr);
 for (a in ignored_arr) {ignored_dict[ignored_arr[a]]=1;}
 }
 (/inet |inet6 / && 0ドル ~ SCOPE && !(2ドル in ignored_dict)) {print 2ドル;}' | \
 while read addr; do
echo "${addr}@$interface"
 done | sort
}
update_addresses_of_interface() {
 ignore_list=2ドル
 set 1ドル 
 interface=1ドル 
 shift
FWB_ADDRS=$(
 for addr in $*; do
echo "${addr}@$interface"
 done | sort
 )
 CURRENT_ADDRS_ALL_SCOPES=""
 CURRENT_ADDRS_GLOBAL_SCOPE=""
 $IP link show dev $interface >/dev/null 2>&1 && {
 CURRENT_ADDRS_ALL_SCOPES=$(list_addresses_by_scope $interface 'scope .*' "$ignore_list")
 CURRENT_ADDRS_GLOBAL_SCOPE=$(list_addresses_by_scope $interface 'scope global' "$ignore_list")
 } || {
 echo "# Interface $interface does not exist"
 # Stop the script if we are not in test mode
 test -z "$FWBDEBUG" && exit 1
 }
 diff_intf missing_address "$FWB_ADDRS" "$CURRENT_ADDRS_ALL_SCOPES" add
 diff_intf missing_address "$CURRENT_ADDRS_GLOBAL_SCOPE" "$FWB_ADDRS" del
}
clear_addresses_except_known_interfaces() {
 $IP link show | sed 's/://g' | awk -v IGNORED="$*" \
 'BEGIN {
 split(IGNORED,ignored_arr);
 for (a in ignored_arr) {ignored_dict[ignored_arr[a]]=1;}
 }
 (/state/ && !(2ドル in ignored_dict)) {print 2ドル;}' | \
 while read intf; do
echo "# Removing addresses not configured in fwbuilder from interface $intf"
 $FWBDEBUG $IP addr flush dev $intf scope global
 $FWBDEBUG $IP link set $intf down
 done
}
check_file() {
 test -r "2ドル" || {
 echo "Can not find file 2ドル referenced by address table object 1ドル"
 exit 1
 }
}
check_run_time_address_table_files() {
 :
}
load_modules() {
 :
 OPTS=1ドル
 MODULES_DIR="/lib/modules/`uname -r`/kernel/net/"
 MODULES=$(find $MODULES_DIR -name '*conntrack*' \! -name '*ipv6*'|sed -e 's/^.*\///' -e 's/\([^\.]\)\..*/1円/')
 echo $OPTS | grep -q nat && {
 MODULES="$MODULES $(find $MODULES_DIR -name '*nat*'|sed -e 's/^.*\///' -e 's/\([^\.]\)\..*/1円/')"
 }
 echo $OPTS | grep -q ipv6 && {
 MODULES="$MODULES $(find $MODULES_DIR -name nf_conntrack_ipv6|sed -e 's/^.*\///' -e 's/\([^\.]\)\..*/1円/')"
 }
 for module in $MODULES; do 
 if $LSMOD | grep ${module} >/dev/null; then continue; fi
 $MODPROBE ${module} || exit 1 
 done
}
verify_interfaces() {
 :
 echo "Verifying interfaces: eth0 lo tun0"
 for i in eth0 lo tun0 ; do
 $IP link show "$i" > /dev/null 2>&1 || {
 log "Interface $i does not exist"
 exit 1
 }
 done
}
prolog_commands() {
 echo "Running prolog script"
}
epilog_commands() {
 echo "Running epilog script"
}
run_epilog_and_exit() {
 epilog_commands
 exit 1ドル
}
configure_interfaces() {
 :
 # Configure interfaces
 update_addresses_of_interface "lo 127.0.0.1/8" ""
 getaddr eth0 i_eth0
 getaddr6 eth0 i_eth0_v6
 getnet eth0 i_eth0_network
 getnet6 eth0 i_eth0_v6_network
 getaddr tun0 i_tun0
 getaddr6 tun0 i_tun0_v6
 getnet tun0 i_tun0_network
 getnet6 tun0 i_tun0_v6_network
}
script_body() {
 # ================ IPv4
 # ================ Table 'filter', automatic rules
 # accept established sessions
 $IPTABLES -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT 
 $IPTABLES -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT 
 $IPTABLES -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT 
 # drop packets that do not match any valid state and log them
 $IPTABLES -N drop_invalid
 $IPTABLES -A OUTPUT -m state --state INVALID -j drop_invalid 
 $IPTABLES -A INPUT -m state --state INVALID -j drop_invalid 
 $IPTABLES -A FORWARD -m state --state INVALID -j drop_invalid 
 $IPTABLES -A drop_invalid -j LOG --log-level debug --log-prefix "INVALID state -- DENY "
 $IPTABLES -A drop_invalid -j DROP
 # ================ Table 'mangle', automatic rules
 $IPTABLES -t mangle -A PREROUTING -j CONNMARK --restore-mark
 $IPTABLES -t mangle -A OUTPUT -j CONNMARK --restore-mark
 # ================ Table 'mangle', rule set Policy
 # 
 # Rule 5 (global)
 # 
 echo "Rule 5 (global)"
 # 
 # HTTP(S)
 $IPTABLES -t mangle -A OUTPUT -p tcp -m tcp -m multiport --dports 80,443 -m state --state NEW -j MARK --set-mark 1
 $IPTABLES -t mangle -A OUTPUT -p tcp -m tcp -m multiport --dports 80,443 -m state --state NEW -j CONNMARK --save-mark
 # ================ Table 'filter', rule set Policy
 # 
 # Rule 0 (eth0)
 # 
 echo "Rule 0 (eth0)"
 # 
 # Anti spoofing rule
 $IPTABLES -N In_RULE_0
 for i_tun0 in $i_tun0_list
 do
test -n "$i_tun0" && $IPTABLES -A INPUT -i eth0 -s $i_tun0 -m state --state NEW -j In_RULE_0 
 done
 for i_eth0 in $i_eth0_list
 do
test -n "$i_eth0" && $IPTABLES -A INPUT -i eth0 -s $i_eth0 -m state --state NEW -j In_RULE_0 
 done
 for i_tun0 in $i_tun0_list
 do
test -n "$i_tun0" && $IPTABLES -A FORWARD -i eth0 -s $i_tun0 -m state --state NEW -j In_RULE_0 
 done
 for i_eth0 in $i_eth0_list
 do
test -n "$i_eth0" && $IPTABLES -A FORWARD -i eth0 -s $i_eth0 -m state --state NEW -j In_RULE_0 
 done
 $IPTABLES -A In_RULE_0 -j LOG --log-level info --log-prefix "SPOOFING DENY "
 $IPTABLES -A In_RULE_0 -j DROP
 # 
 # Rule 1 (lo)
 # 
 echo "Rule 1 (lo)"
 # 
 $IPTABLES -A INPUT -i lo -m state --state NEW -j ACCEPT
 $IPTABLES -A OUTPUT -o lo -m state --state NEW -j ACCEPT
 # 
 # Rule 2 (global)
 # 
 echo "Rule 2 (global)"
 # 
 # Useful ICMP
 $IPTABLES -N RULE_2
 $IPTABLES -A OUTPUT -p icmp -m icmp --icmp-type 3 -m state --state NEW -j RULE_2
 $IPTABLES -A OUTPUT -p icmp -m icmp --icmp-type 0/0 -m state --state NEW -j RULE_2
 $IPTABLES -A OUTPUT -p icmp -m icmp --icmp-type 11/0 -m state --state NEW -j RULE_2
 $IPTABLES -A OUTPUT -p icmp -m icmp --icmp-type 11/1 -m state --state NEW -j RULE_2
 $IPTABLES -A INPUT -p icmp -m icmp --icmp-type 3 -m state --state NEW -j RULE_2
 $IPTABLES -A INPUT -p icmp -m icmp --icmp-type 0/0 -m state --state NEW -j RULE_2
 $IPTABLES -A INPUT -p icmp -m icmp --icmp-type 11/0 -m state --state NEW -j RULE_2
 $IPTABLES -A INPUT -p icmp -m icmp --icmp-type 11/1 -m state --state NEW -j RULE_2
 $IPTABLES -A FORWARD -p icmp -m icmp --icmp-type 3 -m state --state NEW -j RULE_2
 $IPTABLES -A FORWARD -p icmp -m icmp --icmp-type 0/0 -m state --state NEW -j RULE_2
 $IPTABLES -A FORWARD -p icmp -m icmp --icmp-type 11/0 -m state --state NEW -j RULE_2
 $IPTABLES -A FORWARD -p icmp -m icmp --icmp-type 11/1 -m state --state NEW -j RULE_2
 $IPTABLES -A RULE_2 -j LOG --log-level info --log-prefix "ICMP ACCEPT "
 $IPTABLES -A RULE_2 -j ACCEPT
 # 
 # Rule 3 (global)
 # 
 echo "Rule 3 (global)"
 # 
 # Ping request
 $IPTABLES -N Cid4535X4002.0
 $IPTABLES -A OUTPUT -p icmp -m icmp --icmp-type 8/0 -m state --state NEW -j Cid4535X4002.0
 $IPTABLES -N RULE_3
 for i_tun0 in $i_tun0_list
 do
test -n "$i_tun0" && $IPTABLES -A Cid4535X4002.0 -d $i_tun0 -j RULE_3 
 done
 for i_eth0 in $i_eth0_list
 do
test -n "$i_eth0" && $IPTABLES -A Cid4535X4002.0 -d $i_eth0 -j RULE_3 
 done
 $IPTABLES -A INPUT -p icmp -m icmp --icmp-type 8/0 -m state --state NEW -j RULE_3
 $IPTABLES -A RULE_3 -j LOG --log-level info --log-prefix "PING ACCEPT "
 $IPTABLES -A RULE_3 -j ACCEPT
 # 
 # Rule 4 (global)
 # 
 echo "Rule 4 (global)"
 # 
 # SSH Access to the host
 $IPTABLES -N In_RULE_4
 $IPTABLES -A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -j In_RULE_4
 $IPTABLES -A In_RULE_4 -j LOG --log-level info --log-prefix "SSH ACCEPT "
 $IPTABLES -A In_RULE_4 -j ACCEPT
 # 
 # Rule 5 (global)
 # 
 echo "Rule 5 (global)"
 # 
 # HTTP(S)
 $IPTABLES -N Out_RULE_5
 $IPTABLES -A OUTPUT -p tcp -m tcp -m multiport --dports 80,443 -m state --state NEW -j Out_RULE_5
 $IPTABLES -A Out_RULE_5 -j LOG --log-level info --log-prefix "HTTP(S) ACCEPT "
 $IPTABLES -A Out_RULE_5 -j ACCEPT
 # 
 # Rule 6 (global)
 # 
 echo "Rule 6 (global)"
 # 
 # DOMAIN
 $IPTABLES -N Out_RULE_6
 $IPTABLES -A OUTPUT -p udp -m udp --dport 53 -m state --state NEW -j Out_RULE_6
 $IPTABLES -A Out_RULE_6 -j LOG --log-level info --log-prefix "DOMAIN ACCEPT "
 $IPTABLES -A Out_RULE_6 -j ACCEPT
 # 
 # Rule 7 (global)
 # 
 echo "Rule 7 (global)"
 # 
 $IPTABLES -N RULE_7
 $IPTABLES -A OUTPUT -m state --state NEW -j RULE_7
 $IPTABLES -A INPUT -m state --state NEW -j RULE_7
 $IPTABLES -A FORWARD -m state --state NEW -j RULE_7
 $IPTABLES -A RULE_7 -j LOG --log-level warning --log-prefix "LAST RULE DENY "
 $IPTABLES -A RULE_7 -j DROP
}
ip_forward() {
 :
 echo 1 > /proc/sys/net/ipv4/ip_forward
}
reset_all() {
 :
 reset_iptables_v4
}
block_action() {
 reset_all
}
stop_action() {
 reset_all
 $IPTABLES -P OUTPUT ACCEPT
 $IPTABLES -P INPUT ACCEPT
 $IPTABLES -P FORWARD ACCEPT
}
check_iptables() {
 IP_TABLES="1ドル"
 [ ! -e $IP_TABLES ] && return 151
 NF_TABLES=$(cat $IP_TABLES 2>/dev/null)
 [ -z "$NF_TABLES" ] && return 152
 return 0
}
status_action() {
 check_iptables "/proc/net/ip_tables_names"
 ret_ipv4=$?
 check_iptables "/proc/net/ip6_tables_names"
 ret_ipv6=$?
 [ $ret_ipv4 -eq 0 -o $ret_ipv6 -eq 0 ] && return 0
 [ $ret_ipv4 -eq 151 -o $ret_ipv6 -eq 151 ] && {
 echo "iptables modules are not loaded"
 }
 [ $ret_ipv4 -eq 152 -o $ret_ipv6 -eq 152 ] && {
 echo "Firewall is not configured"
 }
 exit 3
}
# See how we were called.
# For backwards compatibility missing argument is equivalent to 'start'
cmd=1ドル
test -z "$cmd" && {
 cmd="start"
}
case "$cmd" in
 start)
 log "Activating firewall script generated Thu Jun 20 02:25:47 2013 by stef"
 check_tools
 prolog_commands 
 check_run_time_address_table_files
 load_modules " "
 configure_interfaces
 verify_interfaces
 reset_all 
 script_body
 ip_forward
 epilog_commands
 RETVAL=$?
 ;;
 stop)
 stop_action
 RETVAL=$?
 ;;
 status)
 status_action
 RETVAL=$?
 ;;
 block)
 block_action
 RETVAL=$?
 ;;
 reload)
 0ドル stop
 0ドル start
 RETVAL=$?
 ;;
 interfaces)
 configure_interfaces
 RETVAL=$?
 ;;
 test_interfaces)
 FWBDEBUG="echo"
 configure_interfaces
 RETVAL=$?
 ;;
 *)
 echo "Usage 0ドル [start|stop|status|block|reload|interfaces|test_interfaces]"
 ;;
esac
exit $RETVAL