Why is there no access to port 8080?

Question

Debian

Good day, dear experts. I've already broken my head. On potru 8080 stratum-proxy is spinning, here is the output of netstat -ntpua | grep8080

(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
tcp        0      0 0.0.0.0:8080            0.0.0.0:*               LISTEN      31067/python

here is iptables-save:

# Generated by iptables-save v1.4.21 on Mon Jul  3 23:39:10 2017
*mangle
:PREROUTING ACCEPT [852:101671]
:INPUT ACCEPT [852:101671]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [638:78947]
:POSTROUTING ACCEPT [638:78947]
COMMIT
# Completed on Mon Jul  3 23:39:10 2017
# Generated by iptables-save v1.4.21 on Mon Jul  3 23:39:10 2017
*filter
:INPUT ACCEPT [264:34966]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [193:24978]
-A INPUT -p tcp -m tcp --dport 8080 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 8080 -j ACCEPT
COMMIT
# Completed on Mon Jul  3 23:39:10 2017
# Generated by iptables-save v1.4.21 on Mon Jul  3 23:39:10 2017
*nat
:PREROUTING ACCEPT [3:160]
:INPUT ACCEPT [3:160]
:OUTPUT ACCEPT [44:2674]
:POSTROUTING ACCEPT [44:2674]
COMMIT
# Completed on Mon Jul  3 23:39:10 2017

Tried to explicitly open access to the port with:
sudo iptables -I INPUT 1 -p tcp --dport 8080 -j ACCEPT
and reset all iptables rules. Can't connect to this port anyway
System:
$ uname -a

Linux instance-11 3.16.0-4-amd64 #1 SMP Debian 3.16.43-2 (2017-04-30) x86_64 GNU/Linux

ifconfig

eth0      Link encap:Ethernet  HWaddr 42:01:0a:80:00:04  
          inet addr:10.128.0.4  Bcast:10.128.0.4  Mask:255.255.255.255
          UP BROADCAST RUNNING MULTICAST  MTU:1460  Metric:1
          RX packets:1242653 errors:0 dropped:0 overruns:0 frame:1
          TX packets:1142948 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:895032638 (853.5 MiB)  TX bytes:163051675 (155.4 MiB)

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:65536  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 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

but the external address is different. essno trying to go to an external address that successfully pinged and ping packets can be seen through tcpdump -i eth0 host
Why is port 8080 closed and how to open it?

Answer 1

Because NAT.
To access outside, you must either have a forwarded port on the gateway or a white IP address.