- Listening for all incoming traffic (Ethernet, ARP, IP, ICMP, TCP, UDP etc)
- Changing IP options (0x14 - 0x3C | + hlen > 5) before sending packets
- Changing Network layer packet as a whole (for example, manual entry source IP and destinaton IP etc)
- Changing Transport layer packet as a whole (for example, manual entry TCP/UDP ports, ICMP type requests etc)
- Is the host alive on the network
- Traceroute with writing IP from output/input interface machine (IP RR & IP TTL respectively)
- Ping
- The realization of the opportunity to reach the machine behind NAT ( IP(SR)+ICMP(ECHO_REQ) )