Hi all, In securing XMPP (Jabber, IM) servers, what role does an iptables firewall play in practice. The XMPP community tend to think of TLS communication channels only and thus iptables becomes somewhat redundant. That is, the XMPP server should handle authentication, deep packet inspection, IP address filtering and so forth. (Of course this is a simplistic view given a firewall helps prevent unprotected services hosted by the XMPP server from being exploited and it helps control DoS etc) However, are XMPP servers deployed in practice like this, where all that is required of the firewall is opening port 5222 for client-to-server communication and port 5269 for server-to-server communication where all traffic is over TLS. I'd imagine that some enterprises want to inspect at the firewall (or even by IDS) layer-7 packet payloads. For example, ensure a user with a JID of xyz@xxxxxxxxxx cannot send packets through the firewall or a particular malware signature or malicious Web URL that is embedded with IM conversations is blocked. In such scenarios, is it best practice to remove the TLS option and thereby loosing some proof of identify (certificates) in favour of deep packet inspection? Are there scenarios where an enterprise that is geographically spread who use VPN's such that they do not require TLS encryption on the XMPP servers? Rather, they are content that their VPN tunnel is providing adequate security coupled with DPI (Deep Packet Inspection) of the XMPP packets and layer 3 and 4 filter also at the firewall? While XMPP servers such as Openfire have TLS functionality end-to-end, are these used in practice by security administrators or is some of the communication desired in the clear for DPI. Presumably two XMPP servers that belong to two different enterprises would not share a VPN channel but use TLS enabled on the XMPP servers instead. Would there be scenarios where xmpp clients are not allowed to connect to the XMPP server except through a HTTP proxy (Perhaps the XMPP server ports are not externally accessible). In that case I presume one could use iptables to inspect the XMPP traffic not just at layers 3 and 4 but some rudimentary l-7 filtering. While I understand that layer 7 filtering should really be left to application specific filters, iptables has some functionality with its "String Match", "U32 Module" and its "L-7 Filter", so in theory at least, its a sensible thing to do, provided there wasn't many iptbales rules requiring layer 7 filtering. Any feedback on personal experiences/scenarios, is greatly welcomed. regards, Paddy. -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
