sslhandle

Section: User Commands (1)
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NAME

sslhandle - preforking TLS server

SYNOPSIS

sslhandle [ opts ] host port prog

DESCRIPTION

opts is a series of getopt-style options, host is a host name or IP address, port is a TCP port, and prog is one or more arguments specifying a program to run for each accepted connection. The server subroutine is called within a loop, with one iteration per request listening to -c n incoming connections simultanously. It must release any resources allocated to handle a particular request before returning to its caller.

The server's address is given by host and port.

BINDINGS

sslhandle will be attached to the primary IP address of host while the host name is fed through qualification using dns_ip6_qualify. If host is given as dotted decimal IPv4 or compactified IPv6 address, sslhandle will bind uniquely to those. In order to bind sslhandle to a LLU IPv6 address (ie. fe80::a:b:c) additionally the interface name -Iifname has to be provided.

Note: The kernel might use temporary changing SLAAC addresses.

sslhandle can be instructed to be multi-homing capable while binding to all available IP addresses. Now host is given as 0.0.0.0 or ::.

Further, sslhandle can be forced to provide dual-stack capabilities, thus allowing IPv4 and IPv6 clients to attach to the same instance once host equals ':0' as pseudo IP address.

port may be a numeric port number or a port name. If port is 0, sslhandle will choose a free port.

SERVING

sslhandle listens for connections from TCP clients. Typically, for each connection, it runs prog, with file descriptor 0 reading from, and file descriptor 1 writing to a child process ssl. The ssl process attempts an SSL accept via the network. If it succeeds, it translates data between prog and the network, performing any necessary SSL encoding and decoding. Before running prog, sslhandle reads and sets certain environment variables.

sslhandle exists, if the parent process receives a SIGTERM.

OPTIONS

General Options:

-q: Quiet. Do not print error messages.
-Q: (Default.) Print error messages.
-v: Verbose. Print error messages and status messages.
-V: Print additional verbose SSL connection informations (protocol and cipher).
Connection options:
-1: After preparing to receive connections, print the local port number to standard output.
-4: Use IPv4 sockets for connections.
-6: Use IPv6 connections. This will set PROTO to TCP6 and put IPv6 addresses in TCP6LOCALIP and TCP6REMOTEIP.
-c n: Do not handle more than n simultaneous connections. If there are n simultaneous connections copies of prog running, defer acceptance of a new connection until one copy finishes. n must be a positive integer. The default value is 40.
-x cdb: Follow the rules compiled into cdb by tcprules. These rules may specify setting environment variables or rejecting connections from bad sources. You can rerun tcprules to change the rules while sslhandle is running.
-X: With -x cdb, allow connections even if -I cdb does not exist. Normally sslhandle will drop the connection if cdb does not exist.
-B banner: Write banner to the network immediately after each SSL connection is made. The banner is subject to SSL encryption.
-f lockfile: Additional filename given for locking. If lockfile is provided and not exclusive readable sslhandle will not start. Utilize this option if your accept system call suffers from the thundering herd problem.
-g gid: Switch group ID to gid after preparing to receive connections. gid must be a positive integer.
-u uid: Switch user ID to uid after preparing to receive connections. uid must be a positive integer.
-U: Same as -g $GID -u $UID. Typically, $GID and $UID are set by envuidgid.
-I ifname: Bind to the network interface ifname ("eth0" on Linux, for example). This is only defined and needed for IPv6 link-local addresses.
-b n: Allow a backlog of approximately n pending connections.
-o: Leave IP options alone. If the client is sending packets along an IP source route, send packets back along the same route.
-O: (Default.) Kill IP options. A client can still use source routing to connect and to send data, but packets will be sent back along the default route.
-d: Delay sending data for a fraction of a second whenever the remote host is responding slowly. This is currently the default, but it may not be in the future; if you want it, set it explicitly.
-D: Never delay sending data; enable TCP_NODELAY.
-t n: Give up on the $SSLREMOTEINFO connection attempt after n seconds. The default value is: 26.
-T n: Give up on the SSL connection attempt after n seconds. The default value is: 26.
-w n: Give up on a connection or program after waiting n seconds for read or write. The default value is: 3600.
SSL and TLS connection options:
-s: Store client and server certificate information in the environment, a la mod_ssl.
-S: (Default.) Do not store client and server certificate information in the environment.
X509 certificate and encryption options:
-3: Read a null-terminated key password from file descriptor 3.
-m: (Mail.) Require valid client certificates, but don't check for matching FQDN.
-z: (Host.) Require valid client certificates and match FQDN (if given) against SAN/DN.
-Z: (Default.) Do not require client certificates.
Data-gathering options:
-h: (Default.) Look up the remote host name in DNS to set the environment variable $SSLREMOTEHOST. In this case, additionally the CN/SAN in the X509 certificate can be checked, provided, the option -z is set.
-H: Do not look up the remote host name in DNS; remove the environment variable $SSLREMOTEHOST. To avoid loops, you must use this option for servers on TCP port 53.
-p: Paranoid. After looking up the remote host name in DNS, look up the IP addresses in DNS for that host name, and remove the environment variable $SSLREMOTEHOST if none of the addresses match the client's IP address.
-P: (Default.) Not paranoid.
-l localname: Do not look up the local host name in DNS; use localname for the environment variable $SSLLOCALHOST. A common choice for localname is 0. To avoid loops, you must use this option for servers on TCP port 53.
-r: Attempt to obtain $SSLREMOTEINFO from the remote host.
-R: (Default.) Do not attempt to obtain $SSLREMOTEINFO from the remote host. To avoid loops, you must use this option for servers on TCP ports 53 and 113.
-e: Set protocol environment a la tcpserver . Set $TCPLOCALIP, $TCPLOCALPORT, $TCPLOCALHOST, $TCPREMOTEIP, $TCPREMOTEPORT, $TCPREMOTEHOST, and $TCPREMOTEINFO as well as for IPv6 connections additionally $TCP6REMOTEIP, $TCP6RMEOTEHOST, and $TCP6REMOTEINFO from the current $SSL environment (see below).
-E: (Default.) Do not set any tcpserver environment variables.

DNS RESOLVER SETTINGS

Use $DNSCACHEIP to set the DNS resolver IP dynamically irrespectively from the settings in /etc/resolv.conf. If the environment variable $LOCALDOMAIN is populated, this name will be appended to unqualified host names. Additional rewriting of local to public names is facilitated in case the file /etc/dnswritefile exists and is populated, or alternatively the environment variable $DNSREWRITEFILE points to a differnent file.

SSL ENVIRONMENT VARIABLES READ

These variables define the run-time environment of sslhandle and are used to specify X509 certificates and keyfile per connection.

$SSL_USER=name: The user, reading the certificates and keyfile.
$SSL_GROUP=group: The respective user group.
$SSL_UID=uid: The numerical UID of the $SSL_USER.
$SSL_CHROOT=path: Perform reading of certificates and keyfile in a $SSL_CHROOT jail.
$CAFILE=path: If set, overrides the compiled-in CA file name. The CA file contains the list of CAs used to verify the client certificate. Certificates in $CAFILE are processed when the server starts.
$CADIR=path: If set, overrides the compiled-in CA directory name. The CA directory contains certificates files used to verify the client certificate. This list augments the list from $CAFILE. Certificates in $CADIR are processed during certificate verification.
$CERTFILE=path: If set, overrides the compiled-in certificate file name. The server presents this certificate to clients.
$CERTCHAINFILE=path: If set, overrides the compiled-in certificate chainfile name. The server presents this list of certificats to clients. Note: Providing $CERTCHAINFILE has precedence over $CERTFILE. Certificates in this file needs to be 'ordered' starting from the uppermost root certificates and placing your host's certificate at the end.
$CIPHERS=string: If set, override the compiled-in SSL cipher list defining the security level for the connection. A typical choice would be 'TLSv1+HIGH:!SSLv2:!MD5'.
$DHFILE=path: If set, overrides the compiled-in DH parameter file name.
$KEYFILE=path: If set, overrides the compiled-in key file name. The key is used when loading the server certificate. Setting $KEYFILE to the empty instructs the server not to use a keyfile when loading it's certificate.
$VERIFYDEPTH=n: If set, overrides the compiled-in verification depth. Default: 1.
$CCAFILE=path: If set, overrides the compiled-in client CA file name for client certificate request. The client CA file contains the list of CAs sent to the client when requesting a client certificate. Note: Setting of $CCAFILE is required while using the option -z or -m. However, declaring $CCAFILE=- disables (on a per-connection base) the client certificate request.
$CCAVERIFY: If set, sslhandle requests a valid client certificate on a per-connection base, unlike the general option -z.

SSL ENVIRONMENT VARAIBLES SET

In case sslhandle is called with the option -e, the following mod_ssl environment variables are provided:

SSL_PROTOCOL

The TLS protocol version (SSLv3, TLSv1, ...).

SSL_SESSION_ID

The hex-encoded SSL session id.

SSL_CIPHER

The cipher specification name.

SSL_CIPHER_USEKEYSIZE

Number of cipher bits (actually used).

SSL_CIPHER_ALGKEYSIZE

Number of cipher bits (possible).

SSL_VERSION_INTERFACE

The mod_ssl program version.

SSL_VERSION_LIBRARY

The OpenSSL program version.

SSL_CLIENT_M_VERSION

The version of the client certificate.

SSL_CLIENT_M_SERIAL

The serial of the client certificate.

SSL_CLIENT_S_DN

Subject DN in client's certificate.

SSL_CLIENT_S_DN_x509

Component of client's Subject DN.

SSL_CLIENT_I_DN

Issuer DN of client's certificate.

SSL_CLIENT_I_DN_x509

Component of client's Issuer DN.

SSL_CLIENT_V_START

Validity of client's certificate (start time).

SSL_CLIENT_V_END

Validity of client's certificate (end time).

SSL_CLIENT_A_SIG

Algorithm used for the signature of client's certificate.

SSL_CLIENT_A_KEY

Algorithm used for the public key of client's certificate.

SSL_CLIENT_CERT

PEM-encoded client certificate.

SSL_CLIENT_CERT_CHAIN n

PEM-encoded certificates in client certificate chain.

SSL_CLIENT_VERIFY

NONE, SUCCESS, GENEROUS or FAILED:reason.

SSL_SERVER_M_SERIAL

The serial of the server certificate.

SSL_SERVER_S_DN

Subject DN in server's certificate.

SSL_SERVER_S_DN_x509

Component of server's Subject DN.

SSL_SERVER_I_DN

Issuer DN of server's certificate.

SSL_SERVER_I_DN_x509

Component of server's Issuer DN.

SSL_SERVER_V_START

Validity of server's certificate (start time).

SSL_SERVER_V_END

Validity of server's certificate (end time).

SSL_SERVER_A_SIG

Algorithm used for the signature of server's certificate.

SSL_SERVER_A_KEY

Algorithm used for the public key of server's certificate.

SSL_SERVER_CERT

PEM-encoded server certificate.
For $SSL_CLIENT_x_DN_x509 and $SSL_SERVER_x_DN_x509, x509 denotes a component of the DN: C, ST, L, O, OU, CN, T, I, G, S, D, UID, Email.

Other SSL environment variables set: PROTO, SSLLOCALHOST, SSLLOCALIP, SSLLOCALPORT, SSLREMOTEHOST, SSLREMOTEINFO, SSLREMOTEIP, SSLREMOTEPORT.

TCP environment variables set: TCPLOCALHOST, TCPLOCALIP, TCPLOCALPORT, TCPREMOTEHOST, TCPREMOTEINFO, TCPREMOTEIP, TCPREMOTEPORT.

TCP6 environment variables set: TCP6INTERFACE, TCP6LOCALHOST, TCP6LOCALIP, TCP6LOCALPORT, TCP6REMOTEHOST, TCP6REMOTEIP, TCP6REMOTEPORT.

LOGGING AND ERROR MESSAGES

sslhandle prints information about individual connections in case -v or -V is specified as argument. TLS error messages are provided if possible:

unable to speak TLS for pid: ... DH lib: TLS handshake failure.
unable to accept TLS for pid: ...: The remote socket was prematurely closed.

REFERENCE

http://httpd.apache.org/docs/2.4/mod/mod_ssl.html http://www.superscript.com/ucspi-ssl/prefork.html

This document was created by man2html, using the manual pages.
Time: 13:07:39 GMT, July 14, 2025