Under Linux, redsocks traffic forwarding combined with iptables traffic transparent transmission appears socket: Too many open files and connect: Bad file descriptor.
Oct 8 18:59:34 localhost redsocks[26193]: connect: Bad file descriptor
Oct 8 18:59:34 localhost redsocks[26193]: [192.168.10.10:53318->124.225.191.19:443]: red_connect_relay: Bad file descriptor
Oct 8 18:59:34 localhost redsocks[26193]: [192.168.10.10:53318->124.225.191.19:443]: dropping client (R/W), relay (R/W), idle 0.000234s
Oct 8 18:59:34 localhost redsocks[26193]: [192.168.10.10:53319->124.225.191.19:8000]: accepted
Oct 8 18:59:34 localhost redsocks[26193]: socket: Too many open files
Oct 8 18:59:35 localhost redsocks[26193]: connect: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53319->124.225.191.19:8000]: red_connect_relay: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53319->124.225.191.19:8000]: dropping client (R/W), relay (R/W), idle 0.000234s
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53320->175.6.44.21:443]: accepted
Oct 8 18:59:35 localhost redsocks[26193]: socket: Too many open files
Oct 8 18:59:35 localhost redsocks[26193]: connect: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53320->175.6.44.21:443]: red_connect_relay: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53320->175.6.44.21:443]: dropping client (R/W), relay (R/W), idle 0.000237s
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53322->175.6.44.21:8000]: accepted
Oct 8 18:59:35 localhost redsocks[26193]: socket: Too many open files
Oct 8 18:59:35 localhost redsocks[26193]: connect: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53322->175.6.44.21:8000]: red_connect_relay: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53322->175.6.44.21:8000]: dropping client (R/W), relay (R/W), idle 0.000236s
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53323->175.6.44.23:443]: accepted
Oct 8 18:59:35 localhost redsocks[26193]: socket: Too many open files
Oct 8 18:59:35 localhost redsocks[26193]: connect: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53323->175.6.44.23:443]: red_connect_relay: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53323->175.6.44.23:443]: dropping client (R/W), relay (R/W), idle 0.000273s
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53325->175.6.44.23:8000]: accepted
Oct 8 18:59:35 localhost redsocks[26193]: socket: Too many open files
Oct 8 18:59:35 localhost redsocks[26193]: connect: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53325->175.6.44.23:8000]: red_connect_relay: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53325->175.6.44.23:8000]: dropping client (R/W), relay (R/W), idle 0.000360s
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53326->124.225.191.18:443]: accepted
Oct 8 18:59:35 localhost redsocks[26193]: socket: Too many open files
Oct 8 18:59:35 localhost redsocks[26193]: connect: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53326->124.225.191.18:443]: red_connect_relay: Bad file descriptor
Oct 8 18:59:35 localhost redsocks[26193]: [192.168.10.10:53326->124.225.191.18:443]: dropping client (R/W), relay (R/W), idle 0.000218s
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:38099->192.168.10.1:8888]: got 1st packet from client
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:38099->192.168.10.1:8888]: socket: Too many open files
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:38099->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:58326->192.168.10.1:8888]: got 1st packet from client
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:58326->192.168.10.1:8888]: socket: Too many open files
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:58326->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:58326->192.168.10.1:8888]: got 1st packet from client
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:58326->192.168.10.1:8888]: socket: Too many open files
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:58326->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:58327->192.168.10.1:8888]: got 1st packet from client
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:58327->192.168.10.1:8888]: socket: Too many open files
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:58327->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:60455->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.10:60455->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:49924->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:49924->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:39003->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:39003->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:33201->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:33201->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:60964->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:60964->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:56258->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:56258->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:43991->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:43991->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:46423->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:46423->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:43075->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:43075->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:37960->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:37960->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:55090->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:55090->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:52716->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:52716->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:59136->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:59136->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:43787->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:43787->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:48279->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:48279->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:59988->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:59988->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:41381->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:41381->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:56439->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:56439->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:39527->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:39527->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:38125->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:38125->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:39793->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:39793->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:33729->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:33729->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:56530->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:56530->192.168.10.1:8888]: Dropping…
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:48387->192.168.10.1:8888]: Client timeout. First: 1696762745, last_client: 1696762746, last_relay: 0.
Oct 8 18:59:36 localhost redsocks[26193]: [192.168.10.1:48387->192.168.10.1:8888]: Dropping…
Solution:
Modify the values of rlimit_nofile and redsocks_conn_max in the redsocks.conf configuration file to a larger value. The sample configuration file is as follows:
Configuration file (/etc/redsocks.conf):
base {<!-- -->
// debug: connection progress & client list on SIGUSR1
log_debug = off;
// info: start and end of client session
log_info = on;
/* possible `log' values are:
*stderr
* "file:/path/to/file"
* syslog:FACILITY facility is any of "daemon", "local0"..."local7"
*/
log = "syslog:daemon";
//detach from console
daemon = on;
/* Change uid, gid and root directory, these options require root
* privileges on startup.
* Note, your chroot may requre /etc/localtime if you write log to syslog.
* Log is opened before chroot & uid changing.
*/
user = redsocks;
group = redsocks;
// chroot = "/var/chroot";
/* possible `redirector' values are:
* iptables - for Linux
* ipf - for FreeBSD
* pf - for OpenBSD
* generic - some generic redirector that MAY work
*/
redirector = iptables;
redsocks_conn_max = 10000;
rlimit_nofile = 10240;
}
redsocks {<!-- -->
/* `local_ip' defaults to 127.0.0.1 for security reasons,
* use 0.0.0.0 if you want to listen on every interface.
* `local_*' are used as port to redirect to.
*/
local_ip = 0.0.0.0;
local_port = 12345;
// `ip' and `port' are IP and tcp-port of proxy-server
// You can also use hostname instead of IP, only one (random)
// address of multihomed host will be used.
ip = 192.168.21.1;
port = 1080;
// known types: socks4, socks5, http-connect, http-relay
type = socks5;
// login = "foobar";
// password = "baz";
}
Sometimes the connection reaches the limit and is forcibly closed. The following is the official documentation:
base {<!-- -->
// debug: connection progress
log_debug = off;
// info: start and end of client session
log_info = on;
/* possible `log' values are:
*stderr
* "file:/path/to/file"
* syslog:FACILITY facility is any of "daemon", "local0"..."local7"
*/
log = stderr;
// log = "file:/path/to/file";
// log = "syslog:local7";
//detach from console
daemon = off;
/* Change uid, gid and root directory, these options require root
* privileges on startup.
* Note, your chroot may requre /etc/localtime if you write log to syslog.
* Log is opened before chroot & uid changing.
* Debian, Ubuntu and some other distributions use `nogroup` instead of
* `nobody`, so change it according to your system if you want redsocks
* to drop root privileges.
*/
// user = nobody;
// group = nobody;
// chroot = "/var/chroot";
/* possible `redirector' values are:
* iptables - for Linux
* ipf - for FreeBSD
* pf - for OpenBSD
* generic - some generic redirector that MAY work
*/
redirector = iptables;
/* Override per-socket values for TCP_KEEPIDLE, TCP_KEEPCNT,
* and TCP_KEEPINTVL. see man 7 tcp for details.
* `redsocks' relies on SO_KEEPALIVE option heavily. */
//tcp_keepalive_time = 0;
//tcp_keepalive_probes = 0;
//tcp_keepalive_intvl = 0;
// Every `redsocks` connection needs two file descriptors for sockets.
// If `splice` is enabled, it also needs four file descriptors for
// pipes. `redudp` is not accounted at the moment. When max number of
// connection is reached, redsocks tries to close idle connections. If
// there are no idle connections, it stops accept()'ing new
// connections, although kernel continues to fill listenq.
// Set maximum number of open file descriptors (also known as `ulimit -n`).
// 0 -- do not modify startup limit (default)
// rlimit_nofile = 0;
// Set maximum number of served connections. Default is to deduce safe
// limit from `splice` setting and RLIMIT_NOFILE.
// redsocks_conn_max = 0;
// Close connections idle for N seconds when/if connection count
// limit is hit.
// 0 -- do not close idle connections
// 7440 -- 2 hours 4 minutes, see RFC 5382 (default)
// connpres_idle_timeout = 7440;
// `max_accept_backoff` is a delay in milliseconds to retry `accept()`
// after failure (e.g. due to lack of file descriptors). It's just a
// safety net for misconfigured `redsocks_conn_max`, you should tune
// redsocks_conn_max if accept backoff happens.
// max_accept_backoff = 60000;
}
redsocks {<!-- -->
/* `local_ip' defaults to 127.0.0.1 for security reasons,
* use 0.0.0.0 if you want to listen on every interface.
* `local_*' are used as port to redirect to.
*/
local_ip = 127.0.0.1;
local_port = 12345;
// listen() queue length. Default value is SOMAXCONN and it should be
// good enough for most of us.
// listenq = 128; // SOMAXCONN equals 128 on my Linux box.
// Enable or disable faster data pump based on splice(2) syscall.
// Default value depends on your kernel version, true for 2.6.27.13 +
// splice = false;
// `ip' and `port' are IP and tcp-port of proxy-server
// You can also use hostname instead of IP, only one (random)
// address of multihomed host will be used.
ip = example.org;
port = 1080;
// known types: socks4, socks5, http-connect, http-relay
type = socks5;
// login = "foobar";
// password = "baz";
// known ways to disclose client IP to the proxy:
// false -- disclose nothing
// http-connect supports:
// X-Forwarded-For -- X-Forwarded-For: IP
// Forwarded_ip -- Forwarded: for=IP # see RFC7239
// Forwarded_ipport -- Forwarded: for="IP:port" # see RFC7239
// disclose_src = false;
// various ways to handle proxy failure
// close -- just close connection (default)
// forward_http_err -- forward HTTP error page from proxy as-is
// on_proxy_fail = close;
}
redudp {<!-- -->
// `local_ip' should not be 0.0.0.0 as it's also used for outgoing
// packets that are sent as replies - and it should be fixed
// if we want NAT to work properly.
local_ip = 127.0.0.1;
local_port = 10053;
// `ip' and `port' of socks5 proxy server.
ip = 10.0.0.1;
port = 1080;
login = username;
password = pazzw0rd;
// redsocks knows about two options while redirecting UDP packets at
// linux: TPROXY and REDIRECT. TPROXY requires more complex routing
// configuration and fresh kernel (>= 2.6.37 according to squid
// developers[1]) but has hack-free way to get original destination
// address, REDIRECT is easier to configure, but requires `dest_ip` and
// `dest_port` to be set, limiting packet redirection to single
// destination.
// [1] http://wiki.squid-cache.org/Features/Tproxy4
dest_ip = 8.8.8.8;
dest_port = 53;
udp_timeout = 30;
udp_timeout_stream = 180;
}
dnstc {<!-- -->
// fake and really dumb DNS server that returns "truncated answer" to
// every query via UDP, RFC-compliant resolver should repeat same query
// via TCP in this case.
local_ip = 127.0.0.1;
local_port = 5300;
}
// you can add more `redsocks' and `redudp' sections if you need.