Trouble with an ip_conntrack_helper

Trouble with an ip_conntrack_helper

[Steven Walter]

I'm getting some interesting behavior while writing an ip_conntrack
helper module.  The primary problem is if I specify a destination port
for the struct ip_conntrack_helper, my help routine is never called.
If I specify a source port, rather than a destination port, the routine
gets called for the various packets in the desired connection.

The problem with this is that I my routine doesn't start getting called
until a packet in the opposite direction arrives, and all packets before
that are never sent by my module.  This makes sense, as the tuple
specifies a /source/ port, which would only occur on reverse traffic.

Here is the chunk of code I'm using to register my helper.  Is there
something really obvious that I'm missing.  I really appreciate any help
you can give.

static struct ip_conntrack_helper icq;

static int __init init(void) {
        memset(&icq, 0, sizeof(struct ip_conntrack_helper));
        icq.tuple.dst.protonum = IPPROTO_UDP;
        icq.tuple.dst.u.udp.port = __constant_htons(4000);
        icq.mask.dst.protonum = 0xffff;
        icq.mask.dst.u.udp.port = 0xffff;
        icq.help = help;
        printk(KERN_INFO "ip_conntrack_icq: registered\n");
        return ip_conntrack_helper_register(&icq);
}


-- 
-Steven
Never ask a geek why, just nod your head and slowly back away.