shadowsocks server, C implementation

SYNOPSIS

ss-server [options]

DESCRIPTION

shadowsocks-c is a lightweight and secure socks5 proxy. It is a port of the original shadowsocks created by clowwindy. shadowsocks-c is written in pure C and takes advantage of libuv to achieve both high performance and low resource consumption.

shadowsocks-c consists of five components. ss-server(1) runs on a remote server to provide secured tunnel service. For more information, check out shadowsocks-libev(8).

OPTIONS

Options include all supported platform variants; restrictions are noted below.

-f <pid_file>: Start shadowsocks as a daemon with specific pid file.

-s <server_host>: Set a server listening hostname or IP address. May be repeated.

-p <server_port>: Set the server listening port.

-k <password>: Set the password. The server and the client should use the same password.

-t <timeout>: Set the socket timeout in seconds. The default value is 60.

-m <encrypt_method>: Set the cipher. The default is chacha20-ietf-poly1305.

AEAD cipher names from the source (availability depends on the build):

constexpr AeadSpec kSpecs[] = {
    { "aes-128-gcm", AeadKind::aes_128_gcm, 16, 12, 16 },
    { "aes-192-gcm", AeadKind::aes_192_gcm, 24, 12, 16 },
    { "aes-256-gcm", AeadKind::aes_256_gcm, 32, 12, 16 },
    { "chacha20-ietf-poly1305", AeadKind::chacha20_poly1305, 32, 12, 16 },
#ifdef crypto_aead_xchacha20poly1305_ietf_ABYTES
    { "xchacha20-ietf-poly1305", AeadKind::xchacha20_poly1305, 32, 24, 16 },
#endif
};

The unauthenticated stream ciphers (aes-256-cfb, chacha20-ietf, rc4-md5 and the like) are no longer supported.The 2022-blake3-* ciphers implement Shadowsocks 2022 (SIP022). They require a base64-encoded pre-shared key supplied with --key or --password (-k): 16 bytes for 2022-blake3-aes-128-gcm and 32 bytes for the other 2022 ciphers. Generate a 32-byte key with openssl rand -base64 32. Passwords are not stretched into keys for these ciphers.

-b <local_address>: Set the local address for outbound connections to destination servers.

-c <config_file>: Use a configuration file.

Refer to shadowsocks-c(8) CONFIG FILE section for more details.

-i <interface>: Send outbound traffic through the specified network interface where supported by the platform.

-d <addr>: Configure name servers for the internal c-ares DNS resolver. By default it uses the system resolver configuration.

-a <user_name>: Run as a specific user.

-n <number>: Specify the maximum number of open files. Requires a platform with setrlimit support.

-h: Print help message.

-u: Enable UDP relay.

-U: Enable UDP relay and disable TCP relay.

-v: Enable verbose mode.

-6: Resolve hostname to IPv6 address first.

-A: Deprecated one-time authentication option. Exits with an error; use AEAD ciphers instead.

--config <config_file>: Read JSON configuration. See the CLI conventions for precedence and default-value behavior. Short alias: -c.

--cipher <encrypt_method>: Select the encryption cipher. See -m for supported cipher names and key requirements. Short alias: -m.

--timeout <timeout>: Same behavior as -t; see that option for details. Short alias: -t.

--user <user_name>: Same behavior as -a; see that option for details. Short alias: -a.

--pid-file <pid_file>: Same behavior as -f; see that option for details. Short alias: -f.

--nofile <number>: Same behavior as -n; see that option for details. Short alias: -n.

--udp: Enable both TCP and UDP relay, overriding the configured mode. Short alias: -u.

--udp-only: Enable UDP relay only, overriding the configured mode. Short alias: -U.

--ipv6-first: Prefer IPv6 DNS results; overrides configuration. This does not restrict connections to IPv6. Short alias: -6.

--verbose: Same behavior as -v; see that option for details. Short alias: -v.

--listen-address <server_host>: Set the listening address. Server and manager addresses may be repeated. Short alias: -s.

--listen-port <server_port>: Set the listening port. Short alias: -p.

--outbound-address <local_address>: Set the source address for connections to destination servers. Short alias: -b.

--interface <interface>: Same behavior as -i; see that option for details. Short alias: -i.

--nameserver <addr>: Same behavior as -d; see that option for details. Short alias: -d.

--version: Print the program name and version to standard output and exit successfully.

--tcp-only: Enable TCP relay only, overriding the configuration file's mode. The last of --tcp-only, --udp, and --udp-only wins.

--ipv4-first: Prefer IPv4 DNS results, overriding ipv6_first in the configuration file. This is an address preference, not a restriction to IPv4. The last of --ipv4-first and --ipv6-first wins.

--fast-open: Enable TCP Fast Open where supported by the operating system.

--reuse-port: Enable port reuse where supported by the operating system.

--tcp-incoming-sndbuf <size>: Set TCP send buffer size for incoming connections.

--tcp-incoming-rcvbuf <size>: Set TCP receive buffer size for incoming connections.

--tcp-outgoing-sndbuf <size>: Set TCP send buffer size for outgoing connections.

--tcp-outgoing-rcvbuf <size>: Set TCP receive buffer size for outgoing connections.

--no-delay: Enable TCP_NODELAY.

--max-connections <number>: Serve at most this many TCP connections at once (default: 1024). Their memory is reserved at startup; a connection beyond the limit is refused until another one closes.

--max-udp-sessions <number>: Keep at most this many UDP associations (default: 256 for clients, 512 for ss-server). When the table is full, the least recently used one is dropped.

--max-dns-queries <number>: Run at most this many DNS lookups at once (default: the connection limit; ss-server adds 64). Beyond the limit ss-server closes the connection that needed the lookup, and ss-local applies its ACL without the address.

--acl <acl_config>: Enable ACL (Access Control List) and specify config file.

--manager-address <address>: Set the manager control address: a UNIX domain socket path or an IP address and port.

--mtu <MTU>: Specify the MTU of your network interface.

--help: Print help message.

--plugin <plugin_name>: Enable SIP003 plugin. (Experimental)

--plugin-opts <plugin_options>: Set SIP003 plugin options. (Experimental)

--password <password>: Set the password. The server and the client should use the same password.

--key <key_in_base64>: Set the key directly. The key should be encoded with URL-safe Base64.

--mptcp: Enable Multipath TCP.

Only available with MPTCP enabled Linux kernel.

--nftables-sets <sets>: Linux builds with USE_NFTABLES only: add malicious IP addresses to nftables sets. Format: [<table1>:]<set1>[,[<table2>:]<set2>...].

EXAMPLE

It is recommended to use a config file when starting ss-server(1).

The config file is written in JSON and is easy to edit. Check out the SEE ALSO section for the default path of config file.

# Start the ss-server

ss-server --config /etc/shadowsocks-libev/config.json

INCOMPATIBILITY

The config file of shadowsocks-libev(8) is slightly different from original shadowsocks.

In order to listen to both IPv4/IPv6 address, use the following grammar in your config json file:

{
"server":["::0","0.0.0.0"],
...
}

ss-server(1) also does not understand "port_password" field in config file. If you want to start up multiple server instances with a single config file, please try ss-manager tool. See ss-manager(8) for details.