Вот такие правила в iptables
Chain INPUT (policy DROP)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:3128
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
ACCEPT icmp -- 192.168.5.5 0.0.0.0/0 icmp type 8
ACCEPT icmp -- 192.168.5.7 0.0.0.0/0 icmp type 8
ACCEPT icmp -- 192.168.5.50 0.0.0.0/0 icmp type 8
ACCEPT icmp -- 192.168.5.50 0.0.0.0/0 icmp type 8
Chain FORWARD (policy DROP)
target prot opt source destination
Chain OUTPUT (policy DROP)
target prot opt source destination
ACCEPT tcp -- 139.94.47.39 0.0.0.0/0
ACCEPT udp -- 139.94.47.39 0.0.0.0/0
ACCEPT tcp -- 192.168.5.50 0.0.0.0/0 multiport sports 3128,22
ACCEPT udp -- 192.168.5.50 0.0.0.0/0 multiport sports 3128,22