ip_nat_sdp_port 461 net/ipv4/netfilter/nf_nat_sip.c !ip_nat_sdp_port(skb, dptr, datalen, mediaoff, medialen, port)) ip_nat_sdp_port 495 net/ipv4/netfilter/nf_nat_sip.c rcu_assign_pointer(nf_nat_sdp_port_hook, ip_nat_sdp_port);