I have a simple requirement/test I'm trying to perform, but having difficulty.
I have a system with 2 interfaces, BoxA:
eth0 172.26.50.102 eth1 192.101.77.62
My goal is to have a tcp port built on BoxA such that hosts on the 192.101.77.0/24 network can reach a port on a different box on the 172.26.0.0/16 network.
The target system is 172.26.10.120 tcp/22 The port I wish to build is 12321.
The iptables rules I'm using:
iptables -A PREROUTING -t nat -i eth1 -p tcp --dport 12321 -j DNAT --to 172.26.10.120:22
It shows up when I query the rules:
boxA# iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination
Chain FORWARD (policy ACCEPT) target prot opt source destination
Chain OUTPUT (policy ACCEPT) target prot opt source destination #
boxA# iptables -L -t nat Chain PREROUTING (policy ACCEPT) target prot opt source destination DNAT tcp -- anywhere anywhere tcp dpt:12321 to:172.26.10.120:22
Chain POSTROUTING (policy ACCEPT) target prot opt source destination
Chain OUTPUT (policy ACCEPT) target prot opt source destination boxA#
Forwarding is enabled:
boxA# cat /proc/sys/net/ipv4/ip_forward 1 boxA#
boxA can get to the target system:
boxA# telnet 172.26.10.120 22 Trying 172.26.10.120... Connected to 172.26.10.120. Escape character is '^]'. SSH-2.0-OpenSSH_4.6
Protocol mismatch. Connection closed by foreign host. boxA#
When I try to connect from my other system, boxB, 192.101.77.76, it never connects to the target port:
boxB# telnet 192.101.77.62 12321 Trying 192.101.77.62... ^C
boxB#
However, I can connect to boxA from boxB on it's tcp/22 port, so I know I have connectivity:
boxB# telnet 192.101.77.62 22 Trying 192.101.77.62... Connected to 192.101.77.62. Escape character is '^]'. SSH-2.0-OpenSSH_5.5p1
Protocol mismatch. Connection closed by foreign host. boxB#
Nothing shows up in the logs.
Anyone have any ideas what I may be doing wrong?
Any help would be great.
Thanks!
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