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iptos(4)							     iptos(4)

  iptos	- Defines the IP Type Of Service (TOS) for FTP and Telnet




  The /etc/iptos file configures the Type Of Service (TOS) of the Internet
  Protocol (IP)	used by	FTP and	Telnet.

  The TOS field	in the Internet	datagram is to specify how the datagram
  should be handled.  It is a mechanism	to allow control information to	have
  precedence over data.

  Generally, protocols that are	involved in direct interaction with a human
  should select	low delay, while data transfers	that involve large blocks of
  data need high throughput.  Finally, high reliability	is most	important for
  datagram-based Internet management functions.

  In the Tru64 UNIX operating system, the ftp and telnet applications and the
  ftpd and telnetd daemons allow the configuring of TOS	values.	 These appli-
  cations check	to see if the /etc/iptos file exists; if the file exists, the
  applications obtain the TOS value from the file and use that value to	set
  the TOS field.  If the /etc/iptos file does not exist, the applications
  default to the following TOS values recommended by RFC1060:

      Low delay

      High throughput

      Low delay

  Users	who want to configure their own	TOS values for the TOS field should
  provide the /etc/iptos file.

  Most IP routers do not differentiate based on	TOS, and therefore providing
  values other than the	default	would have no affect.  You should not change
  the default values for FTP and Telnet.

  Each entry should consist of a single	line of	the form:

       Application  Proto  TOS-bits  aliases

  The entry fields contain the following information:

  The name of an application TOS entry.

  The protocol name for	which the entry	is appropriate.

  The TOS value	to be set for the entry.

  A list of aliases that exist for the entry.

  Items	on an entry line are separated by any number of	blanks,	tabs, or com-
  bination of blanks and tabs.	A number sign (#) indicates that the rest of
  the line is a	comment	and is not interpreted by routines that	search the
  file.	 Blank lines in	the file are ignored.

  Valid	TOS entry names	are ftp-control	and ftp-data for FTP and telnet	for

  The TOS value	for the	entry should be	one of the following hexadecimal
  numbers, corresponding to TOS	bits:

      Low delay

      High throughput

      High reliability

  If you need to disable the use of TOS	bits, because you are having trou-
  bling	communicating with a TCP/IP host that doe not conform entirely with
  the IP specification,	you can	disable	the TOS	bits by	using the the follow-
  ing settings in the /etc/iptos file:

       # Format	of this	file:
       # Application   Proto  TOS-bits	     aliases

       ftp-control     tcp    0x0
       ftp-data		tcp    0x0
       telnet		  tcp	 0x0


  The following	example	shows typical entries in the /etc/iptos	file:

       # Format	of this	file:
       # Application   Proto  TOS-bits	     aliases

       ftp-control     tcp    0x10
       ftp-data		tcp    0x08
       telnet		  tcp	 0x10


  RFC1060, ftp(1), telnet(1), ftpd(8), telnetd(8)