Cisco really make this hard work compared to nearly every other device…so here is my run through using ASDM, this is for RDP
Create NAT Rule
- Click Configuration (top)
- Click Firewall (bottom-left)
- Click NAT Rules (middle-left)
- Select Add->Static NAT Rule
- Original
- Interface: inside
- Source: 192.168.0.99
- Translated
- Interface: Outside
- Select Use Interface IP Address
- Port Address Translation (PAT)
- Check Enable Port Address Translation (PAT)
- Protocol: TCP
- Original Port: 3389
- Translated Port: 3389
- Click OK
Create Access Rule
- Click Access Rules
- Select Add->Add Access Rule
- Interface: outside
- Action: Permit
- Source: any
- Destination: 111.111.111.111 <- the address of your WAN interface
- Service: tcp/3389
- Enable Logging: unchecked