Thank you. Currently am facing an issue.. dunno if it is an issue. please clarify. In a Linux box with tproxy4 (tproxy4-2.6.26-200809262032), I have two proxies, proxy-1 listening on port x and proxy-2 on port y. With the tproxy rules (tproxy-mark, -m socket, and policy routing), I could redirect the incoming traffic to proxy-1 that listens on port x. However, the request from proxy-1 could not be redirected to proxy-2. The second redirection from proxy-1 from proxy-2 is attempted through NAT - OUTPUT rule. The configured rules are given below: ++++++++++++ FOR PROXY-1 +++++++++++++++ iptables -t mangle -A PREROUTING -p tcp --dport 80 -j TPROXY --on-port <proxy-1 port> --tproxy-mark 0x1/0x1 ip rule add fwmark 0x1 lookup 100 ip route add local 0.0.0.0/0 dev lo table 100 iptables -t mangle -N DIVERT iptables -t mangle -I PREROUTING -p tcp -m socket -j DIVERT iptables -t mangle -A DIVERT -j MARK --set-mark 0x1 iptables -t mangle -A DIVERT -j ACCEPT +++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++ FOR PROXY-2 +++++++++++++++++++++++++++++++++++++ iptables -t nat -A OUTPUT -p tcp --dport 80 -j DNAT --to <Interface IP>:<proxy-2 port> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ The rule for proxy-2 makes only the TCP-SYN packet from proxy-1 to be redirected. Three-way handshake is not successful. Am I missing out anything or is this the intended behavior? Thank you. Regards, Arun S. 2008/10/29 Balazs Scheidler <bazsi@balabit.hu>:
On Wed, 2008-10-29 at 20:57 +0530, Arun Srinivasan wrote:
Does this mean, there is an appropriate listening socket in the user space?
not necessarily listening socket, but yes. a socket that is bound to the same address as the destination of the incoming packet.
Apart from IP_TRANSPARENT for the socket option, is there any thing else to be done before binding a socket?
no.
TIA
2008/10/29 Balazs Scheidler <bazsi@balabit.hu>:
On Tue, 2008-10-28 at 18:22 +0530, Arun Srinivasan wrote:
Hi all,
A general question:
Say I have the following rules configured:
+++++++++++++++++++++++++++++ iptables -t mangle -N DIVERT iptables -t mangle -I PREROUTING -p tcp -m socket -j DIVERT iptables -t mangle -A DIVERT -j MARK --set-mark 0x1 iptables -t mangle -A DIVERT -j ACCEPT ++++++++++++++++++++++++++++++++++++
In which case can the tcp packets go without hitting the rule "iptables -t mangle -I PREROUTING -p tcp -m socket -j DIVERT"?
if there's no applicable local socket to the packet in question, then -m socket will not match.
a socket is applicable if the associated tuple (local ip:port, remote ip:port) matches the packet.
related ICMP packets also match.
-- Bazsi
-- Bazsi
-- Regards, Arun S.