Ubuntu Manpage: radsecproxy.conf - Radsec proxy configuration file

NAME

       radsecproxy.conf - Radsec proxy configuration file

DESCRIPTION

       When  the  proxy  server  starts,  it  will  first  check  the  command line arguments, and then read the
       configuration file. Normally radsecproxy will read  the  configuration  file  /etc/radsecproxy.conf.  The
       command line -c option can be used to instead read an alternate file (see radsecproxy(8) for details).

       If the configuration file can not be found, the proxy will exit with an error message. Note that there is
       also  an include facility so that any configuration file may include other configuration files. The proxy
       will also exit on configuration errors.

CONFIGURATION SYNTAX

When the configuration file is processed, whitespace (spaces and tabs) are generally ignored. For each
line, leading and trailing whitespace are ignored. A line is ignored if it is empty, only consists of
whitespace, or if the first non-whitespace character is a #. The configuration is generally case
insensitive, but in some cases the option values (see below) are not.

There are two types of configuration structures than can be used. The first and simplest are lines on the
format option value. That is, an option name, see below for a list of valid options, followed by
whitespace (at least one space or tab character), followed by a value. Note that if the value contains
whitespace, then it must be quoted using "" or ''. Any whitespace in front of the option or after the
value will be ignored.

The other type of structure is a block. A block spans at least two lines, and has the format:

blocktype name {
option value
option value
...
}

That is, some blocktype, see below for a list of the different block types, and then enclosed in braces
you have zero or more lines that each have the previously described option value format. Different block
types have different rules for which options can be specified, they are listed below. The rules regarding
white space, comments and quotes are as above. Hence you may do things like:

blocktype name {
# option value
option "value with space"
...
}

Option value characters can also be written in hex for options requiring a string type value. A %
character followed by two hexadecimal digits will be replaced by its byte value. Longer hex strings can
be escaped with %%. In this case all following hexadecimal digit pairs will be replace by byte values
until the first non-hex character. If a % is used without two following hexadecimal digits, the % and the
following characters are used as written. If you want to write a % and not use this decoding, you may of
course write % in hex; i.e., %25. As %00 would terminate a string, this value is not converted in most
cases, except when used with rewrite statements or secrets.

Some options allow or require the use of regular expressions, denoted as regex. The POSIX extended RE
system is used, see re_format(7).

There is one special option that can be used both as a basic option and inside all blocks. That is the
option Include where the value specifies files to be included. The value can be a single file, or it can
use normal shell globbing to specify multiple files, e.g.:

include /etc/radsecproxy.conf.d/*.conf

The files are sorted alphabetically. Included files are read in the order they are specified, when
reaching the end of a file, the next file is read. When reaching the end of the last included file, the
proxy returns to read the next line following the Include option. Included files may again include other
files.

BASIC OPTIONS

The following basic options may be specified in the configuration file. Note that blocktypes and options
inside blocks are discussed later. Note that none of these options are required, and indeed in many cases
they are not needed. Note that you should specify each at most once. The behaviour with multiple
occurrences is undefined.

PidFile file
The PidFile option specifies the name of a file to which the process id (PID) will be written.
This is overridden by the -i command line option. There is no default value for the PidFile
option.

LogLevel 1-5
This option specifies the debug level. It must be set to 1, 2, 3, 4 or 5, where 1 logs only
serious errors, and 5 logs everything. The default is 2 which logs errors, warnings and a few
informational messages. Note that the command line option -d overrides this.

LogDestination (file|syslog)
This specifies where the log messages should go. By default the messages go to syslog with
facility LOG_DAEMON. Using this option you can specify another syslog facility, or you may specify
that logging should be to a particular file, not using syslog. The value must be either a file URL
like file:///path/to/your/logfile.log or a syslog URL using the syntax: x-syslog:///FACILITY where
FACILITY must be one of LOG_DAEMON, LOG_MAIL, LOG_USER, LOG_LOCAL0, LOG_LOCAL1, LOG_LOCAL2,
LOG_LOCAL3, LOG_LOCAL4, LOG_LOCAL5, LOG_LOCAL6or LOG_LOCAL7. You may omit the facility from the
URL to specify logging to the default facility, but this is not very useful since this is the
default log destination. Note that this option is ignored if -f is specified on the command line.

LogThreadId (on|off)
This can be set to on to include the thread-id in the log messages (useful for debugging).

LogFullUsername (on|off)
This can be set to off to only log the realm in Access-Accept/Reject log messages (for privacy).

LogMAC opt
The LogMAC option can be used to control if and how Calling-Station-Id (the users Ethernet MAC
address) is being logged. It can be set to one of Static, Original, VendorHashed, VendorKeyHashed,
FullyHashed or FullyKeyHashed. The default value for LogMAC is Original.

See radsecproxy.conf-example for details.

LogKey key
The LogKey option is used to specify the key to use when producing HMAC's as an effect of
specifying VendorKeyHashed or FullyKeyHashed for the LogMAC option.

FTicksReporting fticks
The FTicksReporting option is used to enable F-Ticks logging and can be set to None, Basic or
Full. Its default value is None. If FTicksReporting is set to anything other than None, note that
the default value for FTicksMAC needs FTicksKey to be set.

See radsecproxy.conf-example for details.

FTicksMAC opt
The FTicksMAC option has the same function as LogMAC for FTicks. The default for FTicksMAC is
VendorKeyHashed which needs FTicksKey to be set.

Before choosing any of Original, FullyHashed or VendorHashed, consider the implications for user
privacy when MAC addresses are collected. How will the logs be stored, transferred and accessed?

FTicksKey key
The FTicksKey option has the same function as LogKey for Fticks.

FTicksSyslogFacility syslog
The FTicksSyslogFacility option is used to specify a dedicated syslog facility for F-Ticks
messages. This allows for easier filtering of F-Ticks messages. If no FTicksSyslogFacility option
is given, F-Ticks messages are written to what the LogDestination option specifies.

F-Ticks messages are always logged using the log level LOG_DEBUG. Note that specifying a file in
FTicksSyslogFacility (using the file:/// prefix) is not supported.

FTicksPrefix prefix
The FTicksPrefix option is used to set the prefix printed in F-Ticks messages. This allows for use
of F-Ticks messages in non-eduroam environments. If no FTicksPrefix option is given, it defaults
to the prefix used for eduroam (F-TICKS/eduroam/1.0).

ListenUDP (address|*)[:port]
ListenTCP (address|*)[:port]
ListenTLS (address|*)[:port]
ListenDTLS (address|*)[:port]
Listen for the address and port for the respective protocol. Normally the proxy will listen to
the standard ports if configured to handle clients with the respective protocol. The default ports
are 1812 for UDP and TCP and 2083 for TLS and DTLS. On most systems it will do this for all of the
system's IP addresses (both IPv4 and IPv6). On some systems however, it may respond to only IPv4
or only IPv6. To specify an alternate port you may use a value on the form *:port where port is
any valid port number. If you also want to specify a specific address you can do e.g.
192.168.1.1:1812 or [2001:db8::1]:1812. The port may be omitted if you want the default one. Note
that you must use brackets around the IPv6 address. These options may be specified multiple times
to listen to multiple addresses and/or ports for each protocol.

SourceUDP (address|*)[:port]
SourceTCP (address|*)[:port]
SourceTLS (address|*)[:port]
SourceDTLS (address|*)[:port]
This can be used to specify source address and/or source port that the proxy will use for
connecting to clients to send messages (e.g. Access Request). The same syntax as for Listen...
applies.

TTLAttribute (attr|vendor:attr)
This can be used to change the default TTL attribute. Only change this if you know what you are
doing. The syntax is either a numerical value denoting the TTL attribute, or two numerical values
separated by column specifying a vendor attribute.

AddTTL 1-255
If a TTL attribute is present, the proxy will decrement the value and discard the message if zero.
Normally the proxy does nothing if no TTL attribute is present. If you use the AddTTL option with
a value 1-255, the proxy will, when forwarding a message with no TTL attribute, add one with the
specified value. Note that this option can also be specified for a client/server which will
override this setting when forwarding a message to that client/server.

LoopPrevention (on|off)
When this is enabled (on), a request will never be sent to a server named the same as the client
it was received from. I.e., the names of the client block and the server block are compared. Note
that this only gives limited protection against loops. It can be used as a basic option and inside
server blocks where it overrides the basic setting.

IPv4Only (on|off)
IPv6Only (on|off)
Enabling IPv4Only or IPv6Only (on) makes radsecproxy resolve DNS names to the corresponding
address family only, and not the other. This is done for both clients and servers. At most one of
IPv4Only and IPv6Only can be enabled. Note that this can be overridden in client and server
blocks, see below.

SNI (on|off)
Server Name Indication (SNI) is an extension to the TLS protocol. It allows a client to indicate
which hostname it is trying to connect to at the start of the TLS handshake. Enabling this will
use the extension for all TLS and DTLS servers which specify a hostname (not IP address). This can
be overridden in server blocks, see below.

VerifyEAP (on|off)
A radius proxy is mostly agnostic to the contents of the attributes within a radius message and
forwards them as-is. However wrong EAP attributes can lead to bad user experience. Thus
radsecproxy checks the content length of the contained EAP message and denies the access-request
if it doesn't match the attribute length. In case malformatted EAP attributes are inentional, this
behaviour can be disabled (default on).

Include file
This is not a normal configuration option; it can be specified multiple times. It can both be
used as a basic option and inside blocks. For the full description, see the configuration syntax
section above.

BLOCKS

       There  are  five types of blocks, they are client, server, realm, tls and rewrite.  At least one instance
       of each of client and realm is required for the proxy to do anything useful, and it will exit if none are
       configured. The tls block is required if at least one TLS/DTLS client or server is configured. Note  that
       there  can  be  multiple  blocks  for  each  type.  For  each type, the block names should be unique. The
       behaviour with multiple occurrences of the same name for the same block type is undefined. Also note that
       some block option values may reference a block by name, in which case the block name must  be  previously
       defined. Hence the order of the blocks may be significant.

CLIENT BLOCK

client (name|fqdn|(address[/length])) {
...
}

The client block is used to configure a client. That is, tell the proxy about a client, and what
parameters should be used for that client. The name of the client block must (with one exception, see
below) be either the IP address (IPv4 or IPv6) of the client, an IP prefix (IPv4 or IPv6) on the form
IpAddress/PrefixLength, or a domain name (FQDN). The way an FQDN is resolved into an IP address may be
influenced by the use of the IPv4Only and IPv6Only options. Note that literal IPv6 addresses must be
enclosed in brackets.

If a domain name is specified, then this will be resolved immediately to all the addresses associated
with the name, and the proxy will not care about any possible DNS changes that might occur later. Hence
there is no dependency on DNS after startup. However, if the name can not be resolved, startup will fail.

When some client later sends a request to the proxy, the proxy will look at the IP address the request
comes from, and then go through all the addresses of each of the configured clients (in the order they
are defined), to determine which (if any) of the clients this is. When using the IpAddress/PrefixLength
form, this might mask clients defined later, which then will never be matched.

In the case of TLS/DTLS, the name of the client must match the FQDN or IP address in the client
certificate (CN or SubectAltName:DNS or SubjectAltName:IP respectively) and any MatchCertificateAttribute
to be positively identified. Note that no FQDN/IP is checked when using an IP prefix. If overlapping
clients are defined (see section above), they will be searched for positive identification, but only
among clients referencing the same tls block (selected by the first matching IP address or prefix).

The allowed options in a client block are:

Host (fqdn|(address[/length]))
Alternatively of specifying the FQDN or address in the block name, the host option may be used.
In that case, the value of the host option is used as described above, while the name of the block
is only used as a descriptive name for the administrator. The host option may be used multiple
times, and can be a mix of addresses, FQDNs and prefixes.

IPv4Only (on|off)
IPv6Only (on|off)
Enabling IPv4Only or IPv6Only (on) makes radsecproxy resolve DNS names to the corresponding
address family only, and not the other. At most one of IPv4Only and IPv6Only can be enabled. Note
that this will override the global option for this client.

Type type
Specify the type (protocol) of the client. Available options are UDP, TCP, TLS and DTLS.
While TLS and DTLS are secure, enctrypted transports, UDP and TCP are not. Radius uses the shared
secret only to encrypt certain critical attributes, but most of the Radius data is sent in clear.
Protection against manipulation is only provided if the client uses the Message-Authenticator
attribute.
Therefore UDP and TCP should only be used in secured networks or when an underying secure
transport such as IPSEC or MACSEC is used. UDP and TCP SHOULD NOT be used across the internet.

Secret secret
Use secret as the shared RADIUS key with this client. If the secret contains whitespace, the value
must be quoted. This option is optional for TLS/DTLS and if omitted will default to "radsec".
(Note that using a secret other than "radsec" for TLS is a violation of the standard (RFC 6614)
and that the proposed standard for DTLS stipulates that the secret must be "radius/dtls".)

TLS tls
For a TLS/DTLS client you may also specify the tls option. The option value must be the name of a
previously defined TLS block. If this option is not specified, the TLS block with the name
defaultClient or default will be used if defined (in that order). If the specified TLS block name
does not exist, or the option is not specified and none of the defaults exist, the proxy will exit
with an error.

ServerName servername
Use servername for the certificate name check instead of host or the client block name (e.g. if
host uses static IP address).

CertificateNameCheck (on|off)
For a TLS/DTLS client, disable the default behaviour of matching CN or SubjectAltName against the
specified hostname or IP address.

MatchCertificateAttribute CN:/regexp/
MatchCertificateAttribute SubjectAltName:DNS:/regexp/
MatchCertificateAttribute SubjectAltName:URI:/regexp/
MatchCertificateAttribute SubjectAltName:IP:address
MatchCertificateAttribute SubjectAltName:rID:oid
MatchCertificateAttribute SubjectAltName:otherName:oid:/regexp/
Perform additional validation of certificate attributes. Currently matching of CN and
SubjectAltName types URI, DNS, IP, rID, and otherName is supported. If specified multiple times,
all terms must match for the certificate to be considered valid.

PSKkey key
For TLS, use TLS-PSK (pre shared key) instead of certificate based authentication. If specified,
PSKidentity must also be provided. The key must be at least 16 bytes long. To provide the key in
hex, use the %% escaping (see CONFIGURATION SYNTAX).

In addition to the psk, peers must also agree on the key derivation hash function. For this, the
server simply uses the hash function of the negotiated cipher as this negotiation must yield a
compatible cipher anyway. To ensure unambiguous cipher and hash selection, only use ciphers with
the same hash function in the CipherSuites of the tls block. If no tls block is specified, a
default config with SHA256 is used.

Note: only TLS1.3 PSK is supported and only for TLS, not DTLS (pending OpenSSL DTLS1.3 support).

PSKidentity identity
The TLS-PSK identity to identify the client. When omitted, the client name is used as the
identity. When using TLS-PSK, all clients are identified by their PSK identity, however it is
highly recommended to limit the allowed source address(es) using the Host address option.

DuplicateInterval seconds
Specify for how many seconds duplicate checking should be done. If a proxy receives a new request
within a few seconds of a previous one, it may be treated the same if from the same client, with
the same authenticator etc. The proxy will then ignore the new request (if it is still processing
the previous one), or returned a copy of the previous reply.

AddTTL 1-255
The AddTTL option has the same meaning as the option used in the basic config. See the BASIC
OPTIONS section for details. Any value configured here overrides the basic one when sending
messages to this client.

TCPKeepalive (on|off)
Enable TCP keepalive (default is off). If keepalives are not answered within 30s the connection is
considered lost.

FticksVISCOUNTRY cc
Sets this client to be eligible to F-Ticks logging as defined by the FTicksReporting basic option,
and specifies the country to be reported. The country should be specified by the two-letter
country code.

FticksVISINST institution
Set the institution to report in F-Ticks logging. If this option is omitted, the name of the
client block is used.

Rewrite rewrite
This option is deprecated. Use rewriteIn instead.

RewriteIn rewrite
RewriteOut rewrite
Apply the operations in the specified rewrite block on incoming (request) or outgoing (response)
messages from this client. Rewriting incoming messages is done before, outgoing after other
processing. If the RewriteIn is not configured, the rewrite blocks defaultClient or default will
be applied if defined. No default blocks are applied for RewriteOut.

RewriteAttribute User-Name:/regex/replace/
Rewrite the User-Name attribute in a client request for the request forwarded by the proxy. The
User-Name attribute is written back to the original value if a matching response is later sent
back to the client. Example usage:

RewriteAttribute User-Name:/^(.*)@local$/\1@example.com/

RequireMessageAuthenticator (on|off)
Require all Access-Requests be signed with a Message-Authenticator.
This should be enabled if the client is a proxy, or a NAS known to use Message-Authenticator (e.g.
all EAP based NAS like Wifi).
This setting is ignored when using TLS/DTLS transport.

RequireMessageAuthenticatorProxy (on|off)
Require all Access-Requests containing a Proxy-State attribute to be signed with a Message-
Authenticaor.
This should always be enabled if the client is a NAS.
This setting is ignored when using TLS/DLTS transport or when RequireMessageAuthenticator is
enabled.

SERVER BLOCK

server (name|((fqdn|address)[:port])) {
...
}

The server block is used to configure a server. That is, tell the proxy about a server, and what
parameters should be used when communicating with that server. The name of the server block must (with
one exception, see below) be either the IP address (IPv4 or IPv6) of the server, or a domain name (FQDN).
If a domain name is specified, then this will be resolved immediately to all the addresses associated
with the name, and the proxy will not care about any possible DNS changes that might occur later. Hence
there is no dependency on DNS after startup. If the domain name resolves to multiple addresses, then for
UDP/DTLS the first address is used. For TCP/TLS, the proxy will loop through the addresses until it can
connect to one of them. The way an FQDN is resolved into an IP address may be influenced by the use of
the IPv4Only and IPv6Only options.

In the case of TLS/DTLS, the name of the server must match the FQDN or IP address in the server
certificate.

Note that the fqdn or address may include a port number (separated with a column). This port number will
then override the default port or a port option in the server block. Also note that literal IPv6
addresses must be enclosed in brackets.

The allowed options in a server block are:

Host (fqdn|address)[:port]
Alternatively of specifying the FQDN or address in the block name the host option may be used. In
that case, the value of the host option is used as described above, while the name of the block is
only used as a descriptive name for the administrator. Note that multiple host options may be
used. This will then be treated as multiple names/addresses for the same server. When initiating a
TCP/TLS connection, all addresses of all names may be attempted, but there is no failover between
the different host values. For failover use separate server blocks.

Port port
Specify the port (UDP/TCP) to connect to. If omitted, UDP and TCP will default to 1812 while TLS
and DTLS will default to 2083.

Source (address|*)[:port]
Specify the source address and/or port to use for this server. See Source... options above.

DynamicLookupCommand command
Execute the command to dynamically configure a server for a realm given by the username field in
an Access-Request. The command can take two special forms, naptr:service or srv:prefix, or point
to a script or executable.

The naptr: and srv: forms execute the corresponding DNS queries, either searching for service in
NAPTR records (followed by SRV query), or querying for prefix.realm SRV records. Finally a server
block will be constructed for the dynamic realm taking this server block as a template and
overriding the host entries with the content of the SRV records.

Otherwise, the command should be an executable file or script, given with full path, that will be
invoked with the name of the realm as its first and only argument. It should either print a valid
server {...} block containing at least one host statement on stdout and exit with a code of 0, or
print nothing and exit with a non-zero exit code. If the command exited with 0 and provided a
valid server config, it will be combined with the statements in this server block, with the values
returned by the command taking preference.

An example of a shell script resolving the DNS NAPTR records for the realm and then the SRV
records for each NAPTR matching 'x-eduroam:radius.tls' is provided in tools/naptr-eduroam.sh.
This is equivalent to configuring 'naptr:x-eduroam:radius.tls' directly.

ServerName servername
Use servername for the certificate name check instead of host or the server block name (e.g. if
host uses static IP address). Additionally, this name is used for SNI (if enabled), unless
SNIservername is set.

SNI (on|off)
Override gobal SNI setting (see above). This is implicitly enabled if SNIservername is set.

SNIservername sni
Explicitly set the sni to request from the server, in case the server is specified by IP address
or to override the hostname. Implicitly enables SNI for this server.

PSKkey key
PSKidentity identity
The meaning of these options are very similar as for the client block, with minor differences.
- The identity must always be provided and cannot be derived from the server name.
- For the key derivation hash function, the hash function of the first cipher in the CipherSuites
of the referenced tls block is used.

StatusServer (on|off|minimal|auto)
Enable the use of status-server messages for this server (default off). If statusserver is
enabled (on), the proxy will send regular status-server messages to the server to verify that it
is alive. Status tracking of the server will solely depend on status-server message and ignore
lost requests. This should only be enabled if the server supports it. With the option minimal
status-server messages are only sent when regular requests have been lost and no other replies
have been received.

The option auto tries to detect whether the other server supports status-server. If so, status-
server messages are enabled in minimal mode.

RetryCount count
Set how many times the proxy should retry sending a request to the server. Default is 2 retries
for UDP and DTLS. For TCP and TLS it is always 0.
Retries from radius clients are ignored and radsecproxy performs its own retry handling since the
requiremets differ when switching transport protocols.

RetryInterfval interval
Set the interval between each retry. Default is 5s.

Rewrite rewrite
This option is deprecated. Use rewriteIn instead.

RewriteOut rewrite
RewriteIn rewrite
Apply the operations in the specified rewrite block on outgoing (request) or incoming (response)
messages to/from this server. Rewriting outgoing messages is done after, incoming before other
processing. If the RewriteIn is not configured, the rewrite blocks defaultServer or default will
be applied if defined. No default blocks are applied for RewriteOut.

LoopPrevention (on|off)
This overrides the global LoopPrevention option for this server. See section BASIC OPTIONS for
details on this option.

BlockingStartup (on|off)
Start the dynamic server in blocking mode (default off), treating it as if it was already
connected and enqueue requests to this server. Queued requests will be sent out when the
connection is established. If however the dynamic lookup or the connection fails, the queued
requests will be lost. (This is only considered for dynamic lookup servers. Ie when
DynamicLookupCommand is specified) Warning: when the dynamic lookup and connection process is
slow, this wil block the respective realm for that time.

DTLSForceMTU mtu
Some non-Linux platforms are unable to query the MTU of a connection, causing DTLS to limit itself
to 256 bytes and thus failing to connect. Manually set mtu to a large enough value so the initial
DTLS client-hello fits without fragmentation.

RequireMessageAuthenticator (on|off)
Require all responses to Access-Requests be signed with a Message-Authenticator.
This should always be be enabled unless the server is known to only support legacy RADIUS/UDP
behavior.
This setting is ignored when using TLS/DTLS transport.

The meaning and syntax of the following options are exactly the same as for the client block. The details
are not repeated here. Please refer to the definitions in the CLIENT BLOCK section.

IPv4Only (on|off)
IPv6Only (on|off)
Type type
Secret secret
TLS tls
CertificateNameCheck (on|off)
MatchCertificateAttribute ...
AddTTL 1-255
TCPKeepalive (on|off)

REALM BLOCK

realm (*|realm|/regex/) {
...
}

When the proxy receives an Access-Request it needs to figure out to which server it should be forwarded.
This is done by looking at the Username attribute in the request, and matching that against the names of
the defined realm blocks. The proxy will match against the blocks in the order they are specified, using
the first match if any. If no realm matches, the proxy will simply ignore the request. Each realm block
specifies what the server should do when a match is found.

The allowed options in a realm block are:

Server server
AccountingServer server
Specify the server to which requests for this realm should be forwarded. server references a
previously defined server block (see the SERVER BLOCK section). Each server and accountingServer
can be specified multiple times, or omitted completely. If no server is configured, the proxy will
deny all Access-Requests for this realm. If no accountingServer is configured, the proxy will
silently ignore all Accounting-Requests for this realm. See the SERVER SELECTION section below for
details.

AccountingResponse (on|off)
Enable sending Accounting-Response instead of ignoring Accounting-Requests when no accoutingServer
are configured.

AccountingLog (on|off)
When responding to Accounting-Requests (AccountingResponse on), log the accounting data.

ReplyMessage message
Specify a message to be sent back to the client if a Access-Request is denied because no server
are configured.

REALM BLOCK NAMES AND MATCHING
In the general case the proxy will look for a @ in the username attribute, and try to do an exact, case
insensitive match between what comes after the @ and the name of the realm block. So if you get a request
with the attribute value anonymous@example.com, the proxy will go through the realm names in the order
they are specified, looking for a realm block named example.com.

There are two exceptions to this, one is the realm name * which means match everything. Hence if you have
a realm block named *, then it will always match. This should then be the last realm block defined, since
any blocks after this would never be checked. This is useful for having a default.

The other exception is regular expression matching. If the realm name starts with a /, the name is
treated as an regular expression. A case insensitive regexp match will then be done using this regexp on
the value of the entire Username attribute. Optionally you may also have a trailing / after the regexp.
So as an example, if you want to use regexp matching the domain example.com you could have a realm block
named /@example\.com$/. If you want to match all domains under the .com top domain, you could do
/@.*\.com$/. Note that since the matching is done on the entire attribute value, you can also use rules
like /^[a-k].*@example\.com$/ to get some of the users in this domain to use one server, while other
users could be matched by another realm block and use another server.

SERVER SELECTION
Normally requests will be forwarded to the first server option defined. If there are multiple server
options, the proxy will do fail-over and use the second server if the first is down. If the two first are
down, it will try the third etc. If the first server comes back up, it will go back to using that one.
Detection of servers being up or down is based on the use of StatusServer (if enabled), and that
TCP/TLS/DTLS connections are up. Otherwise unanswered requests are used to detect unresponsive servers.
AccountingServers are treated the same, but independently of the other servers.

If there is no Server option (or all dynamic lookups have failed), the proxy will if ReplyMessage is
specified, reply back to the client with an Access Reject message. The message contains a replyMessage
attribute with the value as specified by the ReplyMessage option. Note that this is different from having
no match since then the request is simply ignored. This can be used to catch all undefined sub-domains
or even all undefined realms by configuring either a regex match like /@.*\.example\.com/ or the realm *
with no server option. Another use-case is to block a specific pattern in the username or realm part
using a regex.

If there is no AccountingServer option, the proxy will normally do nothing, ignoring accounting requests.
If instead AccountingResponse is set to on, the proxy will log some of the accounting information and
send an Accounting-Response back. This stops clients from retransmitting Accounting-Request messages when
a realm has no accountingServer configured.

TLS BLOCK

tls name {
...
}

The TLS block specifies TLS configuration options and you need at least one of these if you have clients
or servers using TLS/DTLS. As discussed in the client and server block descriptions, a client or server
block may reference a particular TLS block by name. There are also however the special TLS block names
default, defaultClient and defaultServer which are used as defaults if the client or server block does
not reference a TLS block. Also note that a TLS block must be defined before the client or server block
that would use it. If you want the same TLS configuration for all TLS/DTLS clients and servers, you need
just a single tls block named default, and the client and servers need not refer to it. If you want all
TLS/DTLS clients to use one config, and all TLS/DTLS servers to use another, then you would be fine only
defining two TLS blocks named defaultClient and defaultServer. If you want different clients (or
different servers) to have different TLS parameters, then you may need to create other TLS blocks with
other names, and reference those from the client or server definitions.

As both clients and servers need to present and verify a certificate, both a certificate as well as a CA
to verify the peers certificate must be configured.

The allowed options in a tls block are:

CACertificateFile file
The CA certificate file used to verify the peers certificate. The file can include multiple
certificates as well as CRLs.

CACertificatePath path
The path to search for CA or intermediate certificates and CRLs. All files must have hashed
symbolic links to be found. See openssl-rehash(1).

CertificateFile file
The server certificate this proxy will use. The file may also contain a certificate chain. Any
missing certificates to complete the chain will be searched for in the CACertificateFile and
CACertificatePath.

CertificateKeyFile file
The private-key file for the server certificate specified in CACertificateFile.

CertificateKeyPassword password
The password to decrypt the private-key.

PolicyOID oid
Require the peers certificate to adhere to the policy specified by oid. When specified multiple
times at least one policy must be valid in the peer certificate.

CRLCheck (on|off)
Enable checking peer certificate against the CRL (default off). Note if enabled, all CAs in this
context MUST provide a CRL, otherwise they are considered untrusted.
Note that radsecproxy does not fetch the CRLs itself. This has to be done separately, e.g. with
fetch-crl(8)

CacheExpiry seconds
Specify how many seconds the CA and CRL information should be cached. By default, the CA and CRL
are loaded at startup and cached indefinetely. After the configured time, the CA and CRL are re-
read. Alternatively, reloading the CA and CRL can be triggered by sending a SIGHUP to the
radsecproxy process. This option may be set to zero to disable caching, but be warned: this might
have a huge performance impact.
Any negative value will disable the cache expiry.

CipherList ciphers
Specify the list of accepted ciphers. See openssl-ciphers(1).

CipherSuites ciphersuites
Specify the ciphersuites to be used for TLS1.3. See openssl-ciphers(1).
Note this requires OpenSSL 1.1.1

TlsVersion ( version | minversion:maxversion )
DtlsVersion ( version | minversion:maxversion )
Specify the TLS/DTLS protocol version to be used.
Specify the range of allowed protocol versions between minversion and maxversion (inclusive). If
either is left out, any version up to, or starting from this version is allowed. E.g. "TLS1_2:"
will allow TLSv1.2 or later. If omitted, use the system defaults set in openssl.conf
Currently supported values are SSL3,TLS1,TLS1_1,TLS1_2,TLS1_3 for TLS and DTLS1,DTLS1_2 for DTLS.

DhFile file
DH parameter file to use. See openssl-dhparam(1)
Note: starting with OpenSSL 3.0, use of custom DH parameters is discouraged.

REWRITE BLOCK

rewrite name {
...
}

The rewrite block specifies rules that may rewrite RADIUS messages. It can be used to add, remove and
modify specific attributes from messages received from and sent to clients and servers. As discussed in
the client and server block descriptions, a client or server block may reference a particular rewrite
block by name. There are however also the special rewrite block names default, defaultClient and
defaultServer which are used as defaults if the client or server block does not reference a block. Also
note that a rewrite block must be defined before the client or server block that would use it. If you
want the same rewrite rules for input from all clients and servers, you need just a single rewrite block
named default, and the client and servers need not refer to it. If you want all clients to use one
config, and all servers to use another, then you would be fine only defining two rewrite blocks named
defaultClient and defaultServer. Note that these defaults are only used for rewrite on input. No
rewriting is done on output unless explicitly specified using the RewriteOut option.

The rewrite actions are performed in this sequence:
1. RemoveAttribute (or WhitelistAttribute)
2. ModifyAttribute
3. SupplementAttribute
4. AddAttribute

All options can be specified multiple times. The allowed options in a rewrite block are:

AddAttribute attribute:value
Add an attribute to the radius message and set it to value. The attribute must be specified using
the numerical attribute id. The value can either be numerical, a string, or a hex value. If the
value starts with a number, it is interpreted as a 32bit unsigned integer. Use the ' character at
the start of the value to force string interpretation. When using hex value, it is recommended to
also lead with ' to avoid unintended numeric interpretation. See the CONFIGURATION SYNTAX section
for further details.

AddVendorAttribute vendor:subattribute:value
Add a vendor attribute to the radius message, specified by vendor and subattribute. Both vendor
and subattribute must be specified as numerical values. The format of value is the same as for
addAttribute above.

SupplementAttribute attribute:value
Add an attribute to the radius message and set it to value, only if the attribute is not yet
present on the message. The format of value is the same as for addAttribute above.

SupplementVendorAttribute vendor:subattribute:value
Add a vendor attribute to the radius message only if the subattribute of this vendor is not yet
present on the message. The format of is the same as for addVendorAttribute above.

ModifyAttribute attribute:/regex/replace/
Modify the given attribute using the regex replace pattern. As above, attribute must be specified
by a numerical value. Example usage:

modifyAttribute 1:/^(.*)@local$/\1@example.com/

ModifyVendorAttribute vendor:subattribute:/regex/replace/
Modify the given subattribute of given vendor using the regex replace pattern. Other than the
added vendor, the same syntax as for ModifyAttribute applies.

RemoveAttribute attribute
Remove all attributes with the given id.

RemoveVendorAttribute vendor[:subattribute]
Remove all vendor attributes that match the given vendor and subattribute. If the subattribute is
omitted, all attributes with the given vendor id are removed.

WhitelistMode (on|off)
Enable whitelist mode. All attributes except those configured with WhitelistAttribute or
WhitelistVendorAttribute will be removed. While whitelist mode is active, RemoveAttribute and
RemoveVendorAttribute statements are ignored.

WhitelistAttribute attribute
Do not remove attributes with the given id when WhitelistMode is on. Ignored otherwise.

WhitelistVendorAttribute vendor[:subattribute]
Do not remove vendor attributes that match the given vendor and subattribute when WhitelistMode is
on. Ignored otherwise.

If the subattribute is omitted, the complete vendor attribute is whitelisted. Otherwise only the
specified subattribute is kept but all other subattributes are removed.