Forwarding multiple UDP ports
Hi,
I have a intranet server that initiate UDP connections and I want to forward those connections to and Internet IP.
I have a Linux box with 2 NICs.
My question is: can I forward UDP trafic from and internal server to the Internet? Can I use this line:
iptables -t nat -A PREROUTING -p udp -s INTRA_SERVER -d INTRA_ROUTER --dport 1024:6000 -j DNAT --to-destination INET_IP:1024-6000
I'm testing it and I see the rule matched, the byte and packet counters are incrementing. But, I see no traffic going out of the Internet NIC.
I'm not sure if the multi-port specification will work.
Thanks!
Oliver
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Oliver Schulze L. Get my e-mail after a captcha test in: http://tinymailto.com/oliver
Quoted 5 lines
My question is: can I forward UDP trafic from and internal server to the Internet?
Can I use this line:
Quoted 7 lines
iptables -t nat -A PREROUTING -p udp -s
INTRA_SERVER-dINTRA_ROUTER--dport 1024:6000 -j DNAT --to-destination INET_IP:1024-6000I'm testing it and I see the rule matched, the byte and packet counters are incrementing.
But, I see no traffic going out of the Internet NIC.
I'm not sure if the multi-port specification will work.
Who is INET_IP? Is it the same host as INTRA_ROUTER?
Jan Engelhardt
Hi Jan,
sorry about not specifying.
INTRA_SERVER: intranet ip of the server initiation the udp traffic to the INTRA_ROUTER IPINTRA_ROUTER: intranet ip of the routerINET_IP: a random public IP
The traffic flow should be:INTRA_SERVER -> intranet -> INTRA_ROUTER -> internet -> INET_IP
Explanation:INTRA_SERVER sends UDP traffic to the INTRA_ROUTER IP, then, INTRA_ROUTER forwards those packets to the public IP INET_IP
Thanks
Oliver
Quoted 18 lines · Jan Engelhardt
Quoted 4 lines
My question is: can I forward UDP trafic from and internal server to the Internet?
Can I use this line:Quoted 8 lines
iptables -t nat -A PREROUTING -p udp -s
INTRA_SERVER-dINTRA_ROUTER--dport 1024:6000 -j DNAT --to-destination INET_IP:1024-6000I'm testing it and I see the rule matched, the byte and packet counters are incrementing.
But, I see no traffic going out of the Internet NIC.
I'm not sure if the multi-port specification will work.Who is
INET_IP? Is it the same host asINTRA_ROUTER?Jan Engelhardt
Signature · 2 lines
Oliver Schulze L. Get my e-mail after a captcha test in: http://tinymailto.com/oliver
Quoted 4 lines
Explanation:
INTRA_SERVERsends UDP traffic to theINTRA_ROUTERIP, then,INTRA_ROUTERforwards those packets to the public IPINET_IP
In that case, DNAT is ok. Just make sure that no packet (in either direction) can evade INTRA_ROUTER (such as hubs/switches and other sorts of bridges), because that nullifies NAT.
Jan Engelhardt