$ sudo iptables -vnL
Chain INPUT (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
   64 15065 ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0
  995 84655 ACCEPT     all  --  p255p1 *       0.0.0.0/0            0.0.0.0/0
  117  9628 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0
  300 39219 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:22
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:8000
   33  2364 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:10000
  378  102K ACCEPT     all  --  em1    *       0.0.0.0/0            0.0.0.0/0            state RELATED,ESTABLISHED
   64  5858 LOGGING    all  --  em1    *       0.0.0.0/0            0.0.0.0/0

Chain FORWARD (policy DROP 2 packets, 96 bytes)
 pkts bytes target     prot opt in     out     source               destination
55847   11M ACCEPT     all  --  p255p1 em1     0.0.0.0/0            0.0.0.0/0
60455  177M ACCEPT     all  --  em1    p255p1  0.0.0.0/0            0.0.0.0/0            state RELATED,ESTABLISHED

Chain OUTPUT (policy ACCEPT 2309 packets, 507K bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain LOGGING (1 references)
 pkts bytes target     prot opt in     out     source               destination
   64  5858 LOG        all  --  em1    *       0.0.0.0/0            0.0.0.0/0            limit: avg 5/sec burst 10 LOG flags 0 level 4
   64  5858 DROP       all  --  em1    *       0.0.0.0/0            0.0.0.0/0



$ sudo iptables -t nat -vnL
Chain PREROUTING (policy ACCEPT 2640 packets, 213K bytes)
 pkts bytes target     prot opt in     out     source               destination
    2    96 DNAT       tcp  --  em1    *       0.0.0.0/0            MY_PUB_IP        tcp dpt:8000 to:10.255.50.75:8000

Chain INPUT (policy ACCEPT 1112 packets, 83884 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain OUTPUT (policy ACCEPT 581 packets, 46547 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain POSTROUTING (policy ACCEPT 31 packets, 2017 bytes)
 pkts bytes target     prot opt in     out     source               destination
 1965  158K MASQUERADE  all  --  *      em1     0.0.0.0/0            0.0.0.0/0



#### my IPTABLES rules

# Generated by iptables-save v1.4.21 on Fri Oct  9 13:59:58 2015
*nat
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:PREROUTING ACCEPT [0:0]
-A PREROUTING -p tcp -m tcp -d MY_PUB_IP -i em1 --dport 8000 -j DNAT --to-destination 10.255.50.75:8000
-A POSTROUTING -o em1 -j MASQUERADE
COMMIT
# Completed on Fri Oct  9 13:59:58 2015
# Generated by iptables-save v1.4.21 on Fri Oct  9 13:59:58 2015
*mangle
:PREROUTING ACCEPT [34:3197]
:INPUT ACCEPT [34:3197]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [31:7469]
:POSTROUTING ACCEPT [31:7469]
COMMIT
# Completed on Fri Oct  9 13:59:58 2015
# Generated by iptables-save v1.4.21 on Fri Oct  9 13:59:58 2015
*filter
:LOGGING - [0:0]
:OUTPUT ACCEPT [0:0]
:FORWARD DROP [0:0]
:INPUT DROP [0:0]
-A INPUT -i lo -j ACCEPT
-A INPUT -i p255p1 -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 8000 -j ACCEPT
-A LOGGING -m limit -i em1 --limit 5/second --limit-burst 10 -j LOG
-A LOGGING -i em1 -j DROP
-A INPUT -p tcp -m tcp --dport 10000 -j ACCEPT
-A FORWARD -i p255p1 -o em1 -j ACCEPT
-A INPUT -m state -i em1 --state ESTABLISHED,RELATED -j ACCEPT
-A FORWARD -m state -i em1 -o p255p1 --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -i em1 -j LOGGING
COMMIT
# Completed on Fri Oct  9 13:59:58 2015