I've an update regarding this issue: According to my packet dumps the nf_conntrack_sip.c function: static int process_sdp(struct sk_buff *skb, const char **dptr, unsigned int *datalen, unsigned int cseq) { [...] /* Update session connection and owner addresses */ nf_nat_sdp_session = rcu_dereference(nf_nat_sdp_session_hook); if (nf_nat_sdp_session && ct->status & IPS_NAT_MASK) ret = nf_nat_sdp_session(skb, dptr, sdpoff, datalen, &rtp_addr); if (ret == NF_ACCEPT && i > 0) help->help.ct_sip_info.invite_cseq = cseq; return ret; } ... seems to rewrite the SIP/SDP (IN IP4) owner address and connection address with garbage IP data on REINVITE packets sourcing from NAT outbound to NAT inbound. For example: REINVITE packet sourcing from NAT outbound with connection information: SIP Call IN IP4 212.77.188.67 ... will be rewritten by the garbage IP address: SIP Call IN IP4 128.41.188.128 Should this information not only be rewritten for packets sourcing from NAT inbound to NAT outbound? What information does nf_nat_sip,nf_conntrack_sip read in order to determine the garbage IP? Is this maybe a security (buffer) problem, too? Sorry I'm no coder, so any help is very welcome :) -Florian > -----Original Message----- > From: netfilter-devel-owner@xxxxxxxxxxxxxxx [mailto:netfilter-devel- > owner@xxxxxxxxxxxxxxx] On Behalf Of Florian Fuessl > Sent: Monday, September 28, 2009 7:10 PM > To: netfilter-devel@xxxxxxxxxxxxxxx > Subject: T.38 FAX support via nf_nat_sip,nf_conntrack_sip > > Hi, > > T.38 FAX support via nf_nat_sip,nf_conntraack_sip does currently not > seem to > work, because the REINVITE for the codec change is not handled > correctly at > the moment (Figure: Fax Pass-Through and Call Flow diagram i.e. at > http://docwiki.cisco.com/wiki/Cisco_IOS_Voice_Troubleshooting_and_Monit > oring > _--_Fax_Call_Flow ) > > Do you have an idea how to patch this problem? > > -Florian > > -- > To unsubscribe from this list: send the line "unsubscribe netfilter- > devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html