]> &COMMANDNAME; &VERSION; Björn Påhlsson

belorn@fukt.bsnet.se

Teddy Hogeborn

teddy@fukt.bsnet.se

2008 Teddy Hogeborn Björn Påhlsson This manual page is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This manual page is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; If not, see . &COMMANDNAME; 8 &COMMANDNAME; Sends encrypted passwords to authenticated Mandos clients &COMMANDNAME; --interfaceIF --addressADDRESS --portPORT --priorityPRIORITY --servicenameNAME --configdirDIRECTORY --debug &COMMANDNAME; -iIF -aADDRESS -pPORT --priorityPRIORITY --servicenameNAME --configdirDIRECTORY --debug &COMMANDNAME; --help &COMMANDNAME; --version &COMMANDNAME; --check &COMMANDNAME; is a server daemon which handles incoming request for passwords for a pre-defined list of client host computers. The Mandos server uses Zeroconf to announce itself on the local network, and uses GnuTLS to communicate securely with and to authenticate the clients. Mandos uses IPv6 link-local addresses, since the clients are assumed to not have any other addresses configured. Any authenticated client is then given the pre-encrypted password for that specific client. The purpose of this is to enable remote and unattended rebooting of any client host computer with an encrypted root file system. The client host computer should start a Mandos client in the initial RAM disk environment, the Mandos client program communicates with this server program to get an encrypted password, which is then decrypted and used to unlock the encrypted root file system. The client host computer can then continue its boot sequence normally. -h, --help Show a help message and exit -i, --interface IF Only announce the server and listen to requests on network interface IF. Default is to use all available interfaces. -a, --address ADDRESS If this option is used, the server will only listen to a specific address. This must currently be an IPv6 address; an IPv4 address can be specified using the ::FFFF:192.0.2.3 syntax. Also, if a link-local address is specified, an interface should be set, since a link-local address is only valid on a single interface. By default, the server will listen to all available addresses. -p, --port PORT If this option is used, the server to bind to that port. By default, the server will listen to an arbitrary port given by the operating system. --check Run the server's self-tests. This includes any unit tests, etc. --debug If the server is run in debug mode, it will run in the foreground and print a lot of debugging information. The default is not to run in debug mode. --priority PRIORITY GnuTLS priority string for the TLS handshake with the clients. See gnutls_priority_init 3 for the syntax. The default is SECURE256:!CTYPE-X.509:+CTYPE-OPENPGP. Warning: changing this may make the TLS handshake fail, making communication with clients impossible. --servicename NAME Zeroconf service name. The default is Mandos. You only need to change this if you for some reason want to run more than one server on the same host, which would not normally be useful. If there are name collisions on the same network, the newer server will automatically rename itself to Mandos #2, and so on, therefore this option is not needed in that case. --configdir DIR Directory to search for configuration files. Default is /etc/mandos. See mandos.conf 5 and mandos-clients.conf 5. --version Prints the program version and exit. The Mandos server announces itself as a Zeroconf service of type _mandos._tcp. The Mandos client connects to the announced address and port, and sends a line of text where the first whitespace-separated field is the protocol version, which currently is 1. The client and server then start a TLS protocol handshake with a slight quirk: the Mandos server program acts as a TLS client while the connecting Mandos client acts as a TLS server. The Mandos client must supply an OpenPGP certificate, and the fingerprint of this certificate is used by the Mandos server to look up (in a list read from clients.conf at start time) which binary blob to give the client. No other authentication or authorization is done by the server. Mandos Client Direction Mandos Server Connect -> 1\r\en -> TLS handshake as TLS server <-> TLS handshake as TLS client OpenPGP public key (part of TLS handshake) -> <- Binary blob (client will assume OpenPGP data) <- Close The server will, by default, continually check that the clients are still up. If a client has not been confirmed as being up for some time, the client is assumed to be compromised and is no longer eligible to receive the encrypted password. The timeout, checker program and interval between checks can be configured both globally and per client; see mandos.conf 5 and mandos-clients.conf 5. The server will send log messaged with various severity levels to /dev/log. With the --debug option, it will log even more messages, and also show them on the console. The server will exit with a non-zero exit status only when a critical error is encountered. Use the --configdir option to change where &COMMANDNAME; looks for its configurations files. The default file names are listed here. /etc/mandos/mandos.conf Server-global settings. See mandos.conf 5 for details. /etc/mandos/clients.conf List of clients and client-specific settings. See mandos-clients.conf 5 for details. /var/run/mandos/mandos.pid The file containing the process id of &COMMANDNAME;. /dev/log The Unix domain socket to where local syslog messages are sent. This server might, on especially fatal errors, emit a Python backtrace. This could be considered a feature. Normal invocation needs no options: mandos Run the server in debug mode and read configuration files from the ~/mandos directory: mandos --debug --configdir ~/mandos --servicename Test Run the server normally, but only listen to one interface and only on the link-local address on that interface: mandos --interface eth7 --address fe80::aede:48ff:fe71:f6f2 Running the server should not in itself present any security risk to the host computer running it. The server only gives out its stored data to clients which does have the OpenPGP key of the stored fingerprint. This is guaranteed by the fact that the client sends its OpenPGP public key in the TLS handshake; this ensures it to be genuine. The server computes the fingerprint of the key itself and looks up the fingerprint in its list of clients. The clients.conf file (see mandos-clients.conf 5) must be non-readable by anyone except the user running the server. For more details on client-side security, see password-request 8mandos. password-request 8mandos plugin-runner 8mandos Zeroconf Avahi GnuTLS RFC 4880: OpenPGP Message Format RFC 5081: Using OpenPGP Keys for Transport Layer Security RFC 4291: IP Version 6 Addressing Architecture, section 2.5.6, Link-Local IPv6 Unicast Addresses