http¶

Name¶

http — Central server for RPC and the message database

Synopsis¶

http [-c config]

Description¶

http(8gx) is a trivial HTTP server. It understands the special HTTP methods as used by RPC-over-HTTP protocol as used by Outlook, it can serve files verbatim, or forward requests to a FastCGI server such as php-fpm(8).

Options¶

-c config: Read configuration directives from the given file. If this option is not specified, /etc/gromox/http.cfg will be read if it exists.
-?: Display option summary.

URI processing order¶

Requests are passed to the mod_rewrite(4gx) module (built-in) to have their URI potentially rewritten.
If a HTTP request is using the methods RPC_IN_DATA or RPC_OUT_DATA, the data stream is handed off to the exchange_emsmdb(4gx) plugin.
Otherwise, HTTP processing modules (HPM) are invoked. Processing ends when one module signals that the request was handled. The order depends on the HPM list (which is fixed): ews, mh_emsmdb, mh_nsp, oxdisco, oab.
Otherwise, the mod_fastcgi(4gx) module (built-in) is invoked. Processing ends if the module handled the request.
Otherwise, the mod_cache(4gx) module (built-in) is invoked. Processing ends if the module handled the request.
Otherwise, the request is rejected.

RPC-over-HTTP¶

RPC-over-HTTP utilizes two special HTTP methods, RPC_IN_DATA and RPC_OUT_DATA. These requests can, similarly to HTTP CONNECT, be very long-lived. The RPC data stream is handled by the included exchange_emsmdb(4gx) plugin.

All time-based command-line options and configuration file directives are subject to the syntax described in gromox(7), section "Duration specifications".

Configuration directives (gromox.cfg)¶

The following directives are recognized when reading from /etc/gromox/gromox.cfg, or when the -c option is used to specify a custom file:

daemons_fd_limit: In gromox-http, this is treated as an alias for http_fd_limit.
http_fd_limit: Request that the file descriptor table be at least this large. The magic value 0 indicates that the system default hard limit (rlim_max, cf. setrlimit(2)) should be used.

Default: 0
http_remote_host_hdr: The name of the HTTP request header which contains the actual client IPv6/IPv4 address. When a (reverse) proxy is placed in front of gromox-http, the address gxhttp normally sees is the proxy address (e.g. ::1). If the proxy sets a custom header to convey the actual client address, Gromox can pick this up for its own reporting, which in turn is useful for e.g. fail2ban setups.

Default: (empty)

Configuration directives (http.cfg)¶

The following directives are recognized when reading from /etc/gromox/http.cfg, or when the -c option is used to specify a custom file:

block_interval_auths: The amount of time a user is blocked from connecting to the service after too many failed logins.

Default: 1 minute
config_file_path: Colon-separated list of directories which will be scanned when locating further configuration files, especially those used by plugin instances.

Default: /etc/gromox/http:/etc/gromox
context_average_mem: Default: 256K
context_num: Default: 400
data_file_path: Colon-separated list of directories which will be scanned when locating data files.

Default: /usr/share/gromox/http
fastcgi_exec_timeout: Maximum execution time for CGI scripts.

Default: 10 minutes
gss_program: The helper program to use for authenticating SPNEGO-GSS requests. The value is rudimentarily tokenized at whitespaces, so no special characters may be used. (If you need to, write a shell wrapper.) The special value "internal-gss" uses libgssapi directly. The use of Squid's negotiate_wrapper_auth is optional; Gromox can identify whether requests are SPNEGO-NTLMSSP or SPNEGO-Kerberos in the same fashion as negotiate_wrapper_auth does.

Default: internal-gss

Example: /usr/lib/squid/negotiate_kerberos_auth -s GSS_C_NO_NAME

Example: /usr/lib/squid/negotiate_wrapper_auth --ntlm /usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp --kerberos /usr/lib/squid/negotiate_kerberos_auth -s GSS_C_NO_NAME
host_id: A unique identifier for this system. It is used for the Server HTTP responses header, for service plugins like exmdb_provider(4gx), which makes use of it for SMTP HELO lines, for DSN report texts, for MIDB database/EML cache. The identifier should only use characters allowed for hostnames.

Default: (system hostname)
http_auth_basic: Enable HTTP Basic authentication.

Default: yes
http_auth_spnego: Enable HTTP Negotiate authentication.

Default: no
http_auth_times: The number of login tries a user is allowed before the account is blocked.

Default: 10
http_certificate_passwd: The password to unlock TLS certificates.

Default: (unset)
http_certificate_path: Filesystem path to a certificate file for use with encrypted connections. The complete certificate chain should be present (as there is no other config directive to pull CA certs in).

Default: (unset)
http_conn_timeout: If a HTTP connection stalls for the given period, the connection is terminated.

Default: 3 minutes
http_debug: If set to 1, prints all incoming and outgoing HTTP traffic to stderr.

Default: 0
http_enforce_auth: Enforce authentication at all times. This is a debugging knob.

Default: no
http_krb_service_principal: Default: gromox@host_id
http_listen_addr: AF_INET6 socket address to bind the HTTP service to.

Default: ::
http_listen_port: The TCP port to expose the HTTP protocol service on.

Default: 80
http_listen_tls_port: The TCP port to expose implicit-TLS HTTP protocol service (HTTPS) on.

Default: (unset)
http_log_file: Target for log messages here. Special values: "-" (stderr/syslog depending on parent PID) or "syslog" are recognized.

Default: - (auto)
http_log_level: Maximum verbosity of logging. 1=crit, 2=error, 3=warn, 4=notice, 5=info, 6=debug.

Default: 4 (notice)
http_private_key_path: Filesystem path to the key file needed to unlock the TLS certificate.

Default: (unset)
http_rqbody_flush_size: If the HTTP request to a CGI endpoint has a HTTP body larger than the limit given here, the data is buffered in a file rather than kept in memory. If the request uses Chunked Transfer Encoding, a file is used unconditionally.

Default: 512K
http_rqbody_max_size: If the Content-Length of a HTTP request to a CGI endpoint is larger than this value, the request is rejected.

Default: 50M
http_support_tls: This flag controls whether (or not) the server offers TLS at all. The default is false because you need a certificate for this first.

Default: false
http_thread_charge_num: The maximum number of connections that each thread is allowed to process.

Default: 20
http_thread_init_num: The minimum number of client processing threads to keep around.

Default: 5
msrpc_debug: Log every completed RPC call and the return code of the operation in a minimal fashion to stderr. Level 1 emits RPCs with a failure return code, level 2 emits all RPCs. Note the daemon log level needs to be "debug" (6), too.

Default: 0
ntlmssp_program: Path to samba-winbind ntlm_auth or equivalent program that implements the Squid authentication helper text protocol ("YR, TT, KK, AF"). The value is rudimentarily tokenized at whitespaces, so no special characters may be used. (If you need to, write a shell wrapper.) The use of Squid's negotiate_wrapper_auth is optional; Gromox can identify whether requests are SPNEGO-NTLMSSP or SPNEGO-Kerberos in the same fashion as negotiate_wrapper_auth does.

Default: /usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp

Example: /usr/lib/squid/negotiate_wrapper_auth --ntlm /usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp --kerberos /usr/lib/squid/negotiate_kerberos_auth -s GSS_C_NO_NAME
request_max_mem: The maximum hint size for fragmented RPC PDU requests that will be allowed (C706 §12.6.3.7, MS-RPCE v33 §2.2.2.6).

Default: 4M
tls_min_proto: The lowest TLS version to offer. Possible values are: tls1.0, tls1.1, tls1.2, and, if supported by the system, tls1.3.

Default: tls1.2
running_identity: An unprivileged user account to switch the process to after startup. To inhibit the switch, assign the empty value.

Default: gromox
state_path: Directory for runtime variadic data.

Default: /var/lib/gromox
tcp_mss_size: Sets the TCP_MAXSEG socket option with the given MSS value for the listening socket(s), cf. tcp(7).

Default: 0 (do not limit the MSS)
user_default_lang: Default: en

Files¶

/usr/lib/gromox/libgxh_*.so: HTTP processing plugins
/usr/lib/gromox/libgxp_*.so: PDU processing plugins
/usr/lib/gromox/libgxs_*.so: service plugins

Normative references¶

MS-RPCE: Remote Procedure Call Protocol Extensions
DCERPC / C706: Technical Standard DCE 1.1: Remote Procedure Call by The Open Group, 1997