From ec0ca68f4ed1e6aa6f08f470b18e0198b7e5a4da Mon Sep 17 00:00:00 2001 From: Gert Doering Date: Thu, 15 Aug 2019 17:53:19 +0200 Subject: [PATCH] Increase listen() backlog queue to 32 For reasons historically unknown, OpenVPN sets the listen() backlog queue to "1", which signals the kernel "while there is one TCP connect waiting for OpenVPN to handle it, refuse all others" - which, on restarting a busy TCP server, will create connection issues. The exact "best" value of the backlog queue is subject of discussion, but for a server that is not extremely busy with many connections coming in in parallel, there is no real difference between "10" or "500", as long as it's "more than 1". Found and debugged by "mjo" in Trac. Trac: #1208 Signed-off-by: Gert Doering Acked-by: Antonio Quartulli Acked-by: David Sommerseth Message-Id: <20190815155319.28249-1-gert@greenie.muc.de> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg18758.html Signed-off-by: Gert Doering (cherry picked from commit 6d8380c78bf77766454b93b49ab2ebf713b0be48) --- src/openvpn/socket.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c index c76d20627..9131ec202 100644 --- a/src/openvpn/socket.c +++ b/src/openvpn/socket.c @@ -1170,7 +1170,7 @@ socket_do_listen(socket_descriptor_t sd, ASSERT(local); msg(M_INFO, "Listening for incoming TCP connection on %s", print_sockaddr(local->ai_addr, &gc)); - if (listen(sd, 1)) + if (listen(sd, 32)) { msg(M_ERR, "TCP: listen() failed"); }