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| author | Hannes Frederic Sowa <hannes@stressinduktion.org> | 2013-07-26 17:43:23 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-07-30 16:15:18 -0700 |
| commit | 5ad37d5deee1ff7150a2d0602370101de158ad86 (patch) | |
| tree | 602cac8fe98e0911753b7ff0485756962c2d232a /net/ipv4/tcp_ipv4.c | |
| parent | dcfd8d5830f8cc9062eb7040f455c034e8d160e6 (diff) | |
| download | blackbird-obmc-linux-5ad37d5deee1ff7150a2d0602370101de158ad86.tar.gz blackbird-obmc-linux-5ad37d5deee1ff7150a2d0602370101de158ad86.zip | |
tcp: add tcp_syncookies mode to allow unconditionally generation of syncookies
| If you want to test which effects syncookies have to your
| network connections you can set this knob to 2 to enable
| unconditionally generation of syncookies.
Original idea and first implementation by Eric Dumazet.
Cc: Florian Westphal <fw@strlen.de>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_ipv4.c')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 2a5d5c469d17..280efe5f19c1 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -890,7 +890,7 @@ bool tcp_syn_flood_action(struct sock *sk, NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP); lopt = inet_csk(sk)->icsk_accept_queue.listen_opt; - if (!lopt->synflood_warned) { + if (!lopt->synflood_warned && sysctl_tcp_syncookies != 2) { lopt->synflood_warned = 1; pr_info("%s: Possible SYN flooding on port %d. %s. Check SNMP counters.\n", proto, ntohs(tcp_hdr(skb)->dest), msg); @@ -1462,7 +1462,8 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) * limitations, they conserve resources and peer is * evidently real one. */ - if (inet_csk_reqsk_queue_is_full(sk) && !isn) { + if ((sysctl_tcp_syncookies == 2 || + inet_csk_reqsk_queue_is_full(sk)) && !isn) { want_cookie = tcp_syn_flood_action(sk, skb, "TCP"); if (!want_cookie) goto drop; |
