Problem with NAT

Hi All,

I have a configuration with two PCs.

PC1 is connected to the internet using eth0
======================================================
[root@localhost log]# /sbin/ifconfig
eth0 Link encap:Ethernet HWaddr 00:E0:4C:BE:59:0F
inet addr:89.190.194.54 Bcast:89.190.194.63
Mask:255.255.255.224
inet6 addr: fe80::2e0:4cff:febe:590f/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:66537 errors:0 dropped:0 overruns:0 frame:0
TX packets:5829 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:5840782 (5.5 MiB) TX bytes:620009 (605.4 KiB)
Interrupt:16

eth1 Link encap:Ethernet HWaddr 00:80:AD:7D:C7:21
inet addr:10.120.81.129 Bcast:10.120.81.255
Mask:255.255.255.0
inet6 addr: fe80::280:adff:fe7d:c721/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2346 errors:0 dropped:0 overruns:0 frame:0
TX packets:3768 errors:6 dropped:0 overruns:0 carrier:6
collisions:0 txqueuelen:1000
RX bytes:362721 (354.2 KiB) TX bytes:3263516 (3.1 MiB)
Interrupt:17 Base address:0x2000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:3361 errors:0 dropped:0 overruns:0 frame:0
TX packets:3361 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1850613 (1.7 MiB) TX bytes:1850613 (1.7 MiB)

====================================================
89.190.194.54 is static real IP provided my from my ISP

====================================================
eth1 is a second NIC which is connected to my second PC

====================================================
PC2
root:~> ifconfig
eth0 Link encap:Ethernet HWaddr 02:80:AD:20:31:B8
inet addr:10.120.81.139 Bcast:10.120.81.255
Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1672 errors:0 dropped:0 overruns:0 frame:0
TX packets:1026 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
Interrupt:48

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0


============================================================
I have telnet server on PC2 and would like to connect to it from
outside
(I can telnet PC2 from PC1)

=======================================================
I have specified the following rules in my iptables
[root@localhost log]# /sbin/iptables-save
# Generated by iptables-save v1.3.5 on Thu Jan 25 20:18:56 2007
*nat
:PREROUTING ACCEPT [3279:408077]
:POSTROUTING ACCEPT [6:398]
:OUTPUT ACCEPT [84:5817]
-A PREROUTING -i eth0 -p tcp -m tcp --dport 23 -j DNAT --to-destination
10.120.81.139
-A POSTROUTING -o eth0 -j SNAT --to-source 89.190.194.54
COMMIT
# Completed on Thu Jan 25 20:18:56 2007
# Generated by iptables-save v1.3.5 on Thu Jan 25 20:18:56 2007
*filter
:INPUT ACCEPT [566:48344]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1021:172479]
-A INPUT -s 10.120.81.139 -i eth1 -p tcp -j ACCEPT
-A INPUT -i eth0 -p tcp -j ACCEPT
-A FORWARD -d 89.190.194.54 -i eth0 -p tcp -m tcp --dport 23 -j ACCEPT
COMMIT
# Completed on Thu Jan 25 20:18:56 2007

==================================================================
But still I can not telnet my PC2 from ouside netwok
Can somone tell me what should I try/monitor/sniff so I figure out the
problem.
Note that I am new to linux so probably I am missing something simple

Thank you for your time!
dpenev

.

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