Web hosting provider - With this feature, both sites maintain a count
With this feature, both sites maintain a count of successful connections, which are compared. If they do not match, the handshake fails. This is useful to protect yourself against impostors. Finally, the two uucicos try to agree on a common transfer protocol. This protocol governs the way data is transferred, checked for consistency, and retransmitted in case of an error. There is a need for different protocols because of the differing types of connections supported. For example, telephone lines require a “safe” protocol, which is pessimistic about errors, while TCP transmission is inherently reliable and can use a more efficient protocol that foregoes most extra error checking. After the handshake is complete, the actual transmission phase begins. Both ends turn on the selected protocol driver. At this point, the drivers possibly perform a protocol-specific initialization sequence. The master then sends all files queued for the remote system whose spool grade is high enough. When it has finished, it informs the slave that it is done and that the slave may now hang up. The slave now can either agree to hang up or take over the conversation. This is a change of roles: now the remote system becomes master, and the local one becomes slave. The new master now sends its files. When done, both uucicos exchange termination messages and close the connection. If you need additional information on UUCP, please refer to the source code. There is also a really antique article floating around the Net, written by David A. Novitz, which gives a detailed description of the UUCP protocol.90 The Taylor UUCP FAQ also discusses some details UUCP’s implementation. It is posted to comp.mail.uucp regularly. uucico Command-line Options In this section, we describe the most important command-line options for uucico: - - system, -s system Calls the named system unless prohibited by call-time restrictions. -S system Calls the named system unconditionally. - -master, -r1 Starts uucico in master mode. This is the default when -s or -S is given. All by itself, the -r1 option causes uucico to try to call all systems in the sys file described in the next section of this chapter, unless prohibited by call or retry time restrictions. - -slave, -r0 Starts uucico in slave mode. This is the default when no -s or -S is given. In slave mode, either standard input/output are assumed to be connected to a serial port, or the TCP port specified by the -p option is used. - -ifwork, -C This option supplements -s or -S and tells uucico to call the named system only if there are jobs spooled for it. - -debug type, -x type, -X type Turns on debugging of the specified type. Several types can be given as a comma-separated list. The following types are valid: abnormal, chat, handshake, uucp-proto, proto, port, config, spooldir, execute, incoming, and outgoing. Using all turns on all options. For compatibility with other UUCP implementations, a number may be specified instead, which turns on debugging for the first n items from the above list. Debugging messages will be logged to the Debug file below /var/spool/uucp. It’s also included in the 4.4BSD System Manager’s Manual.