/sbin/iptables -t nat -A PREROUTING -j DNAT -p tcp --dport 8080 --to a.b.c.d:8181
/sbin/iptables -t nat -A POSTROUTING -j SNAT -s 192.168.0.0/255.255.255.0 --to a.b.c.d
echo 1 > /proc/sys/net/ipv4/ip_foward
I check the Fedora iptables setting: /etc/sysconfig/iptables files:
...
:POSTROUTING ACCEPT [0:0]
-A PREROUTING -i eth+ -p tcp --dport 8080 -j DNAT --to-destination a.b.c.d:8080
....
:OUTPUT ACCEPT [0:0]
-A FORWARD -i eth+ -m state --state NEW -m tcp -p tcp -d a.b.c.d --dport 8080 -j ACCEPT
And more rules I add is :
/sbin/iptables -t nat -A POSTROUTING -d a.b.c.d -p tcp --dport 8080 -j MASQUERADE
Then it works! But if I don't use system-config-firewall GUI tools, then how?
Thanks very much !
At 2011-06-27£¬"Marian Marinov" <mm@yuhu.biz> wrote:
>On Monday 27 June 2011 00:08:08 muiz wrote:
>> Thanks Marian,
>> The server only has one IP. I think I should add more iptables records,
>> only one NAT record is not enough,isit correct? If yes , then how?
>
>Huh, I'm sorry yes you need a second rule. So the rules are:
>iptables -t nat -A PREROUTING -j DNAT -p tcp --dport 8080 --to a.b.c.d:8181
>iptables -t nat -A POSTROUTING -j SNAT -s local_ip/local_net --to
>192.168.1.250
>echo 1 > /proc/sys/net/ipv4/ip_foward
>
>The Source NAT(SNAT) rule is needed, cause otherwise the packaets that reach
>a.b.c.d will be comming from the ip of the local client not 192.168.1.250 and
>so 192.168.1.250 will never receive the replies from a.b.c.d.
>Since the packets reach the client directly from a.b.c.d, the client will
>simply disregard them and will wait for packets comming from .1.250.
>
>So the SNAT rule changes the SOURCE IP of the packets to 1.250 so a.b.c.d will
>return the answares to the right source.
>
>Marian
>
>>
>>
>> 2011-06-26 23:38:58£¬"Marian Marinov" <mm@yuhu.biz> wrote£º
>>
>> >On Sunday 26 June 2011 12:53:07 muiz wrote:
>> >> Dear all,
>> >>
>> >> I would like to forward a port to an internet server, but failed. can
>> >> you
>> >>
>> >> help me? Server: eth0: 192.168.1.250, Port: 8080 TCP, CentOS 5.6
>> >> Remote server: IP: a.b.c.d Port: 8181
>> >>
>> >>
>> >> Forward path: client1(192.168.1.10) -> 192.168.1.250:8080 (forward) ->
>> >> a.b.c.d Port: 8181 -----------------------------------------
>> >> In Fedora, I successfully to config the firewall using
>> >> system-config-firewall and iptables command: 1. Run
>> >> system-config-firewall
>> >>
>> >> 1.1 open local port 8080
>> >> 1.2 add a forward rule: local 8080 to remote a.b.c.d:8181, tcp
>> >>
>> >> 2. echo 1 > /proc/sys/net/ipv4/ip_foward
>> >> 3. add a iptables rule: /sbin/iptables -t nat -A POSTROUTING -d a.b.c.d
>> >> -p tcp --dport 8181 -j MASQUERADE That's all.
>> >>
>> >>
>> >>
>> >>
>> >> Thanks !
>> >
>> >You have to use Destination NAT for the job:
>> >
>> >iptables -t nat -A PREROUTING -j DNAT -p tcp --dport 8080 --to
>> >a.b.c.d:8181 echo 1 > /proc/sys/net/ipv4/ip_foward
>> >
>> >If you have more then one IPs on the local machine its a good idea to
>> >specify the destination -d 192.168.1.250
>> >
>> >Marian
>>
>> _______________________________________________
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>> CentOS@centos.org
>> http://lists.centos.org/mailman/listinfo/centos
>
>--
>Best regards,
>Marian Marinov