On Wed, 11 Feb 2015 09:28:34 +0000 Chris Vine <ch...@cvine.freeserve.co.uk> wrote: > With kernel 3.19.0, the following iptables rule, where SSH_TRIES is > set to 4: > > iptables -D SSH_CHAIN -m conntrack --ctstate NEW \ > -m recent --update --seconds $SSH_LOGIN_PERIOD --hitcount > $SSH_TRIES -j DROP > > generates this error message in syslog: > > kernel: xt_recent: hitcount (4) is larger than packets to be > remembered (4) for table DEFAULT > > and the rule fails to install in the table. No error is generated > with kernel 3.18.6.
The rule provoking this should of course have been the one appending the rule, which is: iptables -A SSH_CHAIN -m conntrack --ctstate NEW \ -m recent --update --seconds $SSH_LOGIN_PERIOD --hitcount $SSH_TRIES -j DROP On looking at the code, the changes in the 3.19 kernel seem not to have been tested and there is an off-by-one error. The patch below restores behaviour to be identical to that found in the 3.18 kernel. Chris --- linux-3.19.0/net/netfilter/xt_recent.c~ 2015-02-10 09:18:44.657376355 +0000 +++ linux-3.19.0/net/netfilter/xt_recent.c 2015-02-11 17:58:33.311608835 +0000 @@ -378,7 +378,7 @@ mutex_lock(&recent_mutex); t = recent_table_lookup(recent_net, info->name); if (t != NULL) { - if (info->hit_count > t->nstamps_max_mask) { + if (info->hit_count > t->nstamps_max_mask + 1) { pr_info("hitcount (%u) is larger than packets to be remembered (%u) for table %s\n", info->hit_count, t->nstamps_max_mask + 1, info->name); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/