iptables: O encaminhamento de porta com mascaramento não está funcionando

9

Estou tendo alguns problemas com a porta a frente. O NAT parece funcionar bem e uma das portas a seguir parece funcionar (porta 7887 do udp para a máquina 192.168.1.100). Mas não os outros.

Duvido que isso importe, mas eth1 e eth2 estão localizados em uma NIC de porta dupla.

O acesso à Internet WAN é fornecido com dhcp, portanto, uma solução deve ser independente da WAN_IP, se possível.

/opt/firewall.sh

#!/bin/sh

WAN="eth1"
LAN="eth2"

#ifconfig $LAN up
#ifconfig $LAN 192.168.1.1 netmask 255.255.255.0


echo 1 > /proc/sys/net/ipv4/ip_forward
sysctl -w net.ipv4.ip_forward=1

iptables -F
iptables -t nat -F
iptables -t mangle -F
iptables -X

iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP

iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT

iptables -A INPUT -i $LAN -j ACCEPT
iptables -A OUTPUT -o $WAN -j ACCEPT
iptables -A OUTPUT -o $LAN -j ACCEPT

iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

iptables -A FORWARD -o $LAN -m state --state ESTABLISHED,RELATED -j ACCEPT

iptables -A FORWARD -i $LAN -o $WAN -j ACCEPT
iptables -t nat -A POSTROUTING -o $WAN -j MASQUERADE

# Allow ICMP echo reply/destination unreachable/time exceeded.
iptables -A INPUT -p icmp --icmp-type 0 -j ACCEPT
iptables -A INPUT -p icmp --icmp-type 3 -j ACCEPT
iptables -A INPUT -p icmp --icmp-type 11 -j ACCEPT

# SSH
iptables -t nat -A PREROUTING -p tcp -i $WAN -m multiport --dports 22 -j DNAT --to 192.168.1.250
iptables -A FORWARD -p tcp -i $WAN -o $LAN -d 192.168.1.250 -m multiport --dports 22 -j ACCEPT

# WWW
iptables -t nat -A PREROUTING -p tcp -i $WAN -m multiport --dports 80,443 -j DNAT --to 192.168.1.99
iptables -A FORWARD -p tcp -i $WAN -o $LAN -d 192.168.1.99 -m multiport --dports 80,443 -j ACCEPT

# TOR
iptables -t nat -A PREROUTING -p tcp -i $WAN -m multiport --dports 9001,9030 -j DNAT --to 192.168.1.250
iptables -A FORWARD -p tcp -i $WAN -o $LAN -d 192.168.1.250 -m multiport --dports 9001,9030 -j ACCEPT

# I2P
iptables -t nat -A PREROUTING -p tcp -i $WAN -m multiport --dports 7887 -j DNAT --to 192.168.1.100
iptables -A FORWARD -p tcp -i $WAN -o $LAN -d 192.168.1.100 -m multiport --dports 7887 -j ACCEPT
iptables -t nat -A PREROUTING -p udp -i $WAN -m multiport --dports 7887 -j DNAT --to 192.168.1.100
iptables -A FORWARD -p udp -i $WAN -o $LAN -d 192.168.1.100 -m multiport --dports 7887 -j ACCEPT

iptables -t nat -A PREROUTING -p tcp -i $WAN -m multiport --dports 8887 -j DNAT --to 192.168.1.250
iptables -A FORWARD -p tcp -i $WAN -o $LAN -d 192.168.1.250 -m multiport --dports 8887 -j ACCEPT
iptables -t nat -A PREROUTING -p udp -i $WAN -m multiport --dports 8887 -j DNAT --to 192.168.1.250
iptables -A FORWARD -p udp -i $WAN -o $LAN -d 192.168.1.250 -m multiport --dports 8887 -j ACCEPT

iptables -t nat -L -v

Chain PREROUTING (policy ACCEPT 1047K packets, 80M bytes)
 pkts bytes target     prot opt in     out     source               destination         
    5   232 DNAT       tcp  --  eth1   any     anywhere             anywhere            multiport dports ssh to:192.168.1.250 
    1    60 DNAT       tcp  --  eth1   any     anywhere             anywhere            tcp dpt:www to:192.168.1.99:80 
    0     0 DNAT       tcp  --  eth1   any     anywhere             anywhere            multiport dports 9001,9030 to:192.168.1.250 
    0     0 DNAT       tcp  --  eth1   any     anywhere             anywhere            multiport dports 7887 to:192.168.1.100 
12166 4042K DNAT       udp  --  eth1   any     anywhere             anywhere            multiport dports 7887 to:192.168.1.100 
    0     0 DNAT       tcp  --  eth1   any     anywhere             anywhere            multiport dports 8887 to:192.168.1.250 
    0     0 DNAT       udp  --  eth1   any     anywhere             anywhere            multiport dports 8887 to:192.168.1.250 

Chain POSTROUTING (policy ACCEPT 12313 packets, 4085K bytes)
 pkts bytes target     prot opt in     out     source               destination         
 637K   46M MASQUERADE  all  --  any    eth1    anywhere             anywhere            

Chain OUTPUT (policy ACCEPT 395 packets, 62752 bytes)
 pkts bytes target     prot opt in     out     source               destination

iptables -L -v

Chain INPUT (policy DROP 9336 packets, 846K bytes)
 pkts bytes target     prot opt in     out     source               destination         
    1    76 ACCEPT     all  --  lo     any     anywhere             anywhere            
  467 55711 ACCEPT     all  --  eth2   any     anywhere             anywhere            
   64  5598 ACCEPT     all  --  any    any     anywhere             anywhere            state RELATED,ESTABLISHED 
    0     0 ACCEPT     icmp --  any    any     anywhere             anywhere            icmp echo-reply 
   18  1796 ACCEPT     icmp --  any    any     anywhere             anywhere            icmp destination-unreachable 
    0     0 ACCEPT     icmp --  any    any     anywhere             anywhere            icmp time-exceeded 

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
60586   29M ACCEPT     all  --  any    eth2    anywhere             anywhere            state RELATED,ESTABLISHED 
70888  126M ACCEPT     all  --  eth2   eth1    anywhere             anywhere            
    0     0 ACCEPT     tcp  --  eth1   eth2    anywhere             192.168.1.250       multiport dports ssh 
    0     0 ACCEPT     tcp  --  any    any     anywhere             192.168.1.99        tcp dpt:www state NEW,RELATED,ESTABLISHED 
    0     0 ACCEPT     tcp  --  eth1   eth2    anywhere             192.168.1.250       multiport dports 9001,9030 
    0     0 ACCEPT     tcp  --  eth1   eth2    anywhere             192.168.1.100       multiport dports 7887 
  646  310K ACCEPT     udp  --  eth1   eth2    anywhere             192.168.1.100       multiport dports 7887 
    0     0 ACCEPT     tcp  --  eth1   eth2    anywhere             192.168.1.250       multiport dports 8887 
    0     0 ACCEPT     udp  --  eth1   eth2    anywhere             192.168.1.250       multiport dports 8887 

Chain OUTPUT (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
  157 13421 ACCEPT     all  --  any    lo      anywhere             anywhere            
   76  9678 ACCEPT     all  --  any    eth1    anywhere             anywhere            
  159 26706 ACCEPT     all  --  any    eth2    anywhere             anywhere

Teste de acesso:

 me@external-host $ ssh WAN_IP        
 ssh: connect to host WAN_IP port 22: Connection timed out

 me@external-host $ wget WAN_IP                
 --2012-05-06 15:46:50--  http://WAN_IP/
 Connecting to |WAN_IP|:80... failed: Connection timed out.

Registros de teste de acesso:

 May  8 21:04:18 router kernel: [11692.837693] FOWARD: IN=eth1 OUT=eth2 SRC=130.235.35.233 DST=192.168.1.99 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=35931 DF PROTO=TCP SPT=52319 DPT=80 WINDOW=14600 RES=0x00 SYN URGP=0 
 May  8 21:04:19 router kernel: [11693.837174] FOWARD: IN=eth1 OUT=eth2 SRC=130.235.35.233 DST=192.168.1.99 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=24784 DF PROTO=TCP SPT=52320 DPT=80 WINDOW=14600 RES=0x00 SYN URGP=0 
 May  8 21:04:20 router kernel: [11694.835943] FOWARD: IN=eth1 OUT=eth2 SRC=130.235.35.233 DST=192.168.1.99 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=57280 DF PROTO=TCP SPT=52321 DPT=80 WINDOW=14600 RES=0x00 SYN URGP=0 
 May  8 21:04:21 router kernel: [11695.835159] FOWARD: IN=eth1 OUT=eth2 SRC=130.235.35.233 DST=192.168.1.99 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=10721 DF PROTO=TCP SPT=52322 DPT=80 WINDOW=14600 RES=0x00 SYN URGP=0 
 May  8 21:04:22 router kernel: [11696.833763] FOWARD: IN=eth1 OUT=eth2 SRC=130.235.35.233 DST=192.168.1.99 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=19002 DF PROTO=TCP SPT=52323 DPT=80 WINDOW=14600 RES=0x00 SYN URGP=0 
 May  8 21:04:23 router kernel: [11697.832960] FOWARD: IN=eth1 OUT=eth2 SRC=130.235.35.233 DST=192.168.1.99 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=17468 DF PROTO=TCP SPT=52324 DPT=80 WINDOW=14600 RES=0x00 SYN URGP=0 
 May  8 21:04:24 router kernel: [11698.831733] FOWARD: IN=eth1 OUT=eth2 SRC=130.235.35.233 DST=192.168.1.99 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=32834 DF PROTO=TCP SPT=52325 DPT=80 WINDOW=14600 RES=0x00 SYN URGP=0 
 May  8 21:04:25 router kernel: [11699.830620] FOWARD: IN=eth1 OUT=eth2 SRC=130.235.35.233 DST=192.168.1.99 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=28252 DF PROTO=TCP SPT=52326 DPT=80 WINDOW=14600 RES=0x00 SYN URGP=0 
 May  8 21:04:26 router kernel: [11700.829493] FOWARD: IN=eth1 OUT=eth2 SRC=130.235.35.233 DST=192.168.1.99 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=43537 DF PROTO=TCP SPT=52327 DPT=80 WINDOW=14600 RES=0x00 SYN URGP=0 
 May  8 21:04:27 router kernel: [11701.829118] FOWARD: IN=eth1 OUT=eth2 SRC=130.235.35.233 DST=192.168.1.99 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=55720 DF PROTO=TCP SPT=52328 DPT=80 WINDOW=14600 RES=0x00 SYN URGP=0
iptables  nat  port-forwarding 
— Robert Foss
fonte
Você pode habilitar o log anexando regras como iptables -I INPUT 1 -i $LAN -j LOGdepurar seu problema
— e,
Você deve verificar os contadores na tabela de filtros para ver se alguma coisa está atingindo suas regras de aceitação.
— Falcon Momot
@FalconKirtaran, atualizei a pergunta com os contadores de regras de aceitação.
— Robert Foss
Você pode adicionar uma linha de log ao final da FORWARDcadeia ( iptables -A FORWARD -j LOG) para ver se está caindo ou não.
— Andy Smith
Como eu suspeitava, eles não estão cumprindo a regra de aceitação. No entanto, eles nem estão atingindo a cadeia direta no filtro (porque também não há pacotes descartados).
— Falcon Momot

Respostas:

3

Acontece que uma máquina interna estava inoperante e que minha WAN_IP havia mudado (devido ao dhcp).

Durante minha solução de problemas, aprimorei um pouco o script e agora está totalmente funcional sem ser excessivamente sofisticado. Sinta-se livre para agarrar uma cópia!

/opt/firewall.sh

#!/bin/sh

WAN="eth1"
LAN="eth2"

#ifconfig $LAN up
#ifconfig $LAN 192.168.1.1 netmask 255.255.255.0

echo 1 > /proc/sys/net/ipv4/ip_forward
sysctl -w net.ipv4.ip_forward=1

iptables -F
iptables -t nat -F
iptables -t mangle -F
iptables -X

#
# Debug logging
#iptables -I INPUT 1 --source 130.235.35.233/31 -j LOG --log-prefix "INPUT: "
#iptables -I FORWARD 1 --source 130.235.35.233/31 -j LOG --log-prefix "FOWARD: "


#
# Default to drop packets
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP

#
# Allow all local loopback traffic
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT

#
# Allow output on $WAN and $LAN if. Allow input on $LAN if.
iptables -A INPUT -i $LAN -j ACCEPT
iptables -A OUTPUT -o $WAN -j ACCEPT
iptables -A OUTPUT -o $LAN -j ACCEPT

iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

iptables -A FORWARD -o $LAN -m state --state ESTABLISHED,RELATED -j ACCEPT

iptables -A FORWARD -i $LAN -o $WAN -j ACCEPT
iptables -t nat -A POSTROUTING -o $WAN -j MASQUERADE

# Allow ICMP echo reply/echo request/destination unreachable/time exceeded
iptables -A INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT
iptables -A INPUT -p icmp --icmp-type time-exceeded -j ACCEPT
iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT

# SSH
iptables -t nat -A PREROUTING -p tcp -i $WAN -m multiport --dports 22 -j DNAT --to 192.168.1.250
iptables -A FORWARD -p tcp -i $WAN -o $LAN -d 192.168.1.250 -m multiport --dports 22 -j ACCEPT

# WWW
iptables -t nat -A PREROUTING -p tcp -i $WAN -m multiport --dports 80,443 -j DNAT --to 192.168.1.99
iptables -A FORWARD -p tcp -i $WAN -o $LAN -d 192.168.1.99 -m multiport --dports 80,443 -j ACCEPT

# TOR
iptables -t nat -A PREROUTING -p tcp -i $WAN -m multiport --dports 9001,9030 -j DNAT --to 192.168.1.250
iptables -A FORWARD -p tcp -i $WAN -o $LAN -d 192.168.1.250 -m multiport --dports 9001,9030 -j ACCEPT

# I2P
iptables -t nat -A PREROUTING -p tcp -i $WAN -m multiport --dports 7887 -j DNAT --to 192.168.1.100
iptables -A FORWARD -p tcp -i $WAN -o $LAN -d 192.168.1.100 -m multiport --dports 7887 -j ACCEPT
iptables -t nat -A PREROUTING -p udp -i $WAN -m multiport --dports 7887 -j DNAT --to 192.168.1.100
iptables -A FORWARD -p udp -i $WAN -o $LAN -d 192.168.1.100 -m multiport --dports 7887 -j ACCEPT

iptables -t nat -A PREROUTING -p tcp -i $WAN -m multiport --dports 8887 -j DNAT --to 192.168.1.250
iptables -A FORWARD -p tcp -i $WAN -o $LAN -d 192.168.1.250 -m multiport --dports 8887 -j ACCEPT
iptables -t nat -A PREROUTING -p udp -i $WAN -m multiport --dports 8887 -j DNAT --to 192.168.1.250
iptables -A FORWARD -p udp -i $WAN -o $LAN -d 192.168.1.250 -m multiport --dports 8887 -j ACCEPT


exit 0 #report success
— Robert Foss
fonte
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