NG_CHECKSUM_CSUM_IPV4
conf->csum_flags &= NG_CHECKSUM_CSUM_IPV4|NG_CHECKSUM_CSUM_IPV6;
conf->csum_offload &= NG_CHECKSUM_CSUM_IPV4|NG_CHECKSUM_CSUM_IPV6;
m->m_pkthdr.csum_flags &= ~NG_CHECKSUM_CSUM_IPV4;
if (m->m_pkthdr.csum_flags & (NG_CHECKSUM_CSUM_IPV4|NG_CHECKSUM_CSUM_IPV6))
(m->m_pkthdr.csum_flags & NG_CHECKSUM_CSUM_IPV4)) {
~(NG_CHECKSUM_CSUM_IPV4|NG_CHECKSUM_CSUM_IPV6);
if (m->m_pkthdr.csum_flags & NG_CHECKSUM_CSUM_IPV4)
~(NG_CHECKSUM_CSUM_IPV4|NG_CHECKSUM_CSUM_IPV6);