| Reference | Purpose | Needs bpf_tap? | Would if_simloop()'s bpf_tap work? | Could do bpf write? |
|---|---|---|---|---|
| net/if_ethersubr.c:333 | Loopback broadcast on simplex interface | NO (outbound copy will be copied) | NO (simloop uses DLT_NULL encapsulation, this is a DLT_EN10MB interface) | NO |
| net/if_ethersubr.c:336 | Loopback unicasts to me on simplex interface | YES (no outbound copy for security reasons) | NO (simloop uses DLT_NULL encapsulation, this is a DLT_EN10MB interface) | NO |
| net/if_fddisubr.c:342 | Loopback broadcast on simplex interface | NO (outbound copy will be copied) | NO (simloop uses DLT_NULL encapsulation, this is a DLT_FDDI interface) | NO |
| net/if_fddisubr.c:346 | Loopback unicasts to me on simplex interface | YES (no outbound copy for security reasons) | NO (simloop uses DLT_NULL encapsulation, this is a DLT_FDDI interface) | NO |
| net/if_iso88025subr.c:291 | Loopback broadcast on simplex interface | NO (outbound copy will be copied) | NO (simloop uses DLT_NULL encapsulation, this is a DLT_IEEE802 interface) | NO |
| net/if_iso88025subr.c:295 | Loopback unicasts to me on simplex interface | YES (no outbound copy for security reasons) | NO (simloop uses DLT_NULL encapsulation, this is a DLT_IEEE802 interface) | NO |
| net/if_loop.c:189 | Looping back packet from looutput() | YES | YES | YES |
| netatalk/ddp_output.c:225 | Short-circuiting packet sent to ourself. | YES (no outbound copy) | UNLIKELY (simloop uses DLT_NULL encapsulation, this could be any kind of interface) | NO |
| netatm/ipatm/ipatm_output.c:142 | Sending IP-over-ATM packet destined for our IP address. | YES (no outbound copy) | ? (simloop uses DLT_NULL encapsulation, I can't figure out what kind of interface this is likely to be -- I couldn't find an ATM driver that does BPF) | NO |
| netinet/ip_output.c:1895 | Looping back multicasts sent on sockets that have IP_MULTICAST_LOOP set. | NO (outbound copy is sufficient) | UNLIKELY (simloop uses DLT_NULL encapsulation, this could be any kind of interface) | NO |
| netinet6/ip6_mroute.c:1783 | Inputting decapsulated PIM Register packet. (What does IPv4 do? Why is IPv6 different?) | YES (if bpf is supported on register pseudo-interface) | ? (is bpf supported on PIM register pseudo-interfaces? What DLT_ type?) | NO |
| netinet6/ip6_output.c:2153 | Looping back multicasts sent on sockets that have IPV6_MULTICAST_LOOP set. | NO (outbound copy is sufficient) | UNLIKELY (simloop uses DLT_NULL encapsulation, this could be any kind of interface) | NO |
Summary: