iptables port forwarding + remote debugging

[riyer]

Hi,

Here is the situation:

Machine_A (eth0: 192.168.0.253)
Machine_B (eth0: 192.168.0.100, eth1: 10.0.0.100)
Machine_C (eth1: 10.0.0.3)

I want to remotely debug a process on Machine_C from Machine_A. However, since they are in two different networks, I am trying to setup port forwarding using iptables (192.168.0.100:50003::10.0.0.3:2000), i.e. all requests on port 50003 on Machine_B (192.168.0.100) would be forwarded to port 2000 on Machine_C (10.0.0.3).

Assuming port forwarding works fine, I will start gdbserver on Machine_C to listen on port 2000, while Machine_A will use 'target remote 192.168.0.100:50003'.

Does this sound right?

If so, I am not able to get it working. Here is the iptables script I have run on 192.168.0.100:

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 50003 -j DNAT --to 10.0.0.3:2000
iptables -t nat -A POSTROUTING -i eth0 -s 10.0.0.3 -p tcp --sport 2000 -j MASQUERADE --to 50003

I would appreciate any help/comments in this regard.
Thanks in advance,
Best regards,
R. Iyer

[Lazydog]

Hi,

Here is the situation:

Machine_A (eth0: 192.168.0.253)
Machine_B (eth0: 192.168.0.100, eth1: 10.0.0.100)
Machine_C (eth1: 10.0.0.3)

I want to remotely debug a process on Machine_C from Machine_A. However, since they are in two different networks, I am trying to setup port forwarding using iptables (192.168.0.100:50003::10.0.0.3:2000), i.e. all requests on port 50003 on Machine_B (192.168.0.100) would be forwarded to port 2000 on Machine_C (10.0.0.3).

Assuming port forwarding works fine, I will start gdbserver on Machine_C to listen on port 2000, while Machine_A will use 'target remote 192.168.0.100:50003'.

Does this sound right?

If so, I am not able to get it working. Here is the iptables script I have run on 192.168.0.100:

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 50003 -j DNAT --to 10.0.0.3:2000
iptables -t nat -A POSTROUTING -i eth0 -s 10.0.0.3 -p tcp --sport 2000 -j MASQUERADE --to 50003

I would appreciate any help/comments in this regard.
Thanks in advance,
Best regards,
R. Iyer

You might want to change the second rule from '-i' to '-o'

[riyer]

Hi Robert,

Thanks for your reply.

I tried to change the option from -i to -o as you suggested. However, it does not seem to work.

Also, I want to know if anyone has tried doing remote debugged through ports mapped by iptables?

Best regards,
R. Iyer