Revise paste troubleshooting connectivity

## find ports listening 
netstat -an | grep 8000 
netstat -an | grep LISTEN

## test connection
telnet 10.0.3.30 8000

## find ports listening 
sudo ss -tulpn | grep 8000
tcp   LISTEN 0      10            0.0.0.0:8000      0.0.0.0:*    users:(("python3",pid=273874,fd=4))

## firewall rules
sudo iptables -L INPUT -n -v
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
6207K   25G ACCEPT     0    --  *      *       0.0.0.0/0            0.0.0.0/0            state RELATED,ESTABLISHED
    4   336 ACCEPT     1    --  *      *       0.0.0.0/0            0.0.0.0/0           
 260K   27M ACCEPT     0    --  lo     *       0.0.0.0/0            0.0.0.0/0           
   13   780 ACCEPT     6    --  *      *       0.0.0.0/0            0.0.0.0/0            state NEW tcp dpt:22
  247 10680 REJECT     0    --  *      *       0.0.0.0/0            0.0.0.0/0            reject-with icmp-host-prohibited
    0     0 ACCEPT     6    --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:8000
    0     0 ACCEPT     6    --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:8000
    0     0 ACCEPT     6    --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:8000

## list firewll rules
sudo iptables -L INPUT --line-numbers -n
Chain INPUT (policy ACCEPT)
num  target     prot opt source               destination         
1    ACCEPT     6    --  0.0.0.0/0            0.0.0.0/0            state NEW tcp dpt:3000
2    ACCEPT     0    --  0.0.0.0/0            0.0.0.0/0            state RELATED,ESTABLISHED
3    ACCEPT     1    --  0.0.0.0/0            0.0.0.0/0           
4    ACCEPT     0    --  0.0.0.0/0            0.0.0.0/0           
5    ACCEPT     6    --  0.0.0.0/0            0.0.0.0/0            tcp dpt:8000
6    ACCEPT     6    --  0.0.0.0/0            0.0.0.0/0            state NEW tcp dpt:22
7    REJECT     0    --  0.0.0.0/0            0.0.0.0/0            reject-with icmp-host-prohibited
8    ACCEPT     6    --  0.0.0.0/0            0.0.0.0/0            state NEW tcp dpt:3000

## delete line 5
sudo iptables -D INPUT 6

## add new rule above REJECT
sudo iptables -I INPUT 5 -p tcp --dport 8000 -j ACCEPT
sudo netfilter-persistent save

## create server process to listen port 5432
nc -l -p 5432