NAME

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

SYNOPSIS

/etc/iptos

DESCRIPTION

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 applications 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:

ftp-control
Low delay

ftp-data
High throughput

telnetLow delay

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

Note

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:

Application
The name of an application TOS entry.

Proto
The protocol name for which the entry is appropriate.

TOS-bits
The TOS value to be set for the entry.

aliases
A list of aliases that exist for the entry.

Items on an entry line are separated by any number of blanks, tabs, or combination 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 Telnet. 

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

0x10Low delay

0x08High throughput

0x04High reliability

If you need to disable the use of TOS bits, because you are having troubling 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 following 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

EXAMPLES

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

RELATED INFORMATION

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