iptables redirect udp traffic from one interface to another, or from one host to another on the same interface

Joshua

11/1/22, 6:11 AM

iptables -t nat -A PREROUTING -p udp -m udp --dport 1197 -j DNAT --to-destination 1.2.3.4:8081

On eth0 I am receiving udp packes destined for port 1197. I want to emit those packets on another interface and change the destination ip and port. This doesn't seem to be working according to wireshark. I have ip forwarding enabled

My longer term goal is to split two udp streams that are arriving on the same port from two different ips, so that one stream goes to a different port, and I am having trouble simulating that in my current network (sending udp data to my laptop from a different host, i.e. not use the loopback because that requires a different set of rules)

Alternatively, I am trying to use iptables -t nat -A PREROUTING -p udp -s $SRC_IP --dport $DPORT -j DNAT --to-destination $NEW_IP:$NEW_PORT where SRC_IP and NEW_IP are on the same interface. I basically want to reflect this traffic to a new host on the same network

-t mangle -j TEE also doesn't seem to be doing anything

0 + 1

iptables

udp

Tero Kilkanen

11/1/22, 7:04 AM

Please describe your network topology, how exactly are different hosts connected.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: iptables redirect udp traffic from one interface to another, or from one host to another on the same interface

TH: iptables เปลี่ยนเส้นทางการรับส่งข้อมูล udp จากอินเทอร์เฟซหนึ่งไปยังอีกโฮสต์หนึ่ง หรือจากโฮสต์หนึ่งไปยังอีกโฮสต์หนึ่งบนอินเทอร์เฟซเดียวกัน

RO: iptables redirecționează traficul udp de la o interfață la alta sau de la o gazdă la alta pe aceeași interfață

RU: iptables перенаправляет udp-трафик с одного интерфейса на другой или с одного хоста на другой на том же интерфейсе

VI: iptables chuyển hướng lưu lượng truy cập udp từ giao diện này sang giao diện khác hoặc từ máy chủ này sang máy chủ khác trên cùng một giao diện

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