Hello Danushka, >I am trying to use a Linux box as a pass-through node using rinetd >as a port forwarding mechanism. I see that TOS is always zero on >the egress path so that my receiver does not receive the TOS values >I set on the sender. Do you need the TCP session to be terminated in userspace (and re-initiated)? That's what's happening with rinetd. You are using it as a TCP proxy. The Linux box is acting as a (TCP) receiver on one side, and initiating a brand new TCP connection outbound. That's why the ToS value is changing. Next question: When you say 'pass-through' node, I am not certain what you mean. Do you want your Linux box to act like a router? If so, then, that's very easy: sysctl -w net.ipv4.ip_forward=1 Now, you have a router. Send packets to the ultimate destination from your sender node. Make sure that you configure your routes properly (maybe that's already done). >Is there a way to solve this issue?. Maybe rinetd does not copy the >values properly?. I do not know rinetd. Perhaps somebody else does. >Probably there is a better/smarter way to do port forwarding (getting >my Linux box to work just as a pass-through node). Please let me know >if there is any other way to do that. How many values are you changing in the packet? Just the destination port? Also the destination address? I'm thinking that iptables NAT may provide you a solution. Assuming you are just messing with the destination address and port, you should be able to use iptables DNAT. I'd suggest reading these: http://linux-ip.net/html/nat-dnat.html https://www.frozentux.net/iptables-tutorial/chunkyhtml/x4033.html Good luck, -Martin -- Martin A. Brown http://linux-ip.net/ -- To unsubscribe from this list: send the line "unsubscribe lartc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
