HP-UX Reference (11i v2 03/08) - 4 File Formats (vol 8)

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ppp.Systems(4) ppp.Systems(4)

\q Don’t print following send strings (e.g. a password) in any debugging or logging output.

Subsequent \q sequences toggle ‘quiet’ mode.

\A Parse the incoming string as an IP address, written as four decimal numbers separated

by periods, and use it for the local end of the point-to-point connection (receive only).

EXAMPLE

In the example below, we call host ‘everyone’ using a Telebit PEP modem with its DTE interface set at

19200 bps. We call host ‘nobody’ using a V.32/V.42/V.42bis modem that’s capable of driving a 38400 DTE,

and we are connected to host ‘someone’ via a direct cable attached to

/dev/ttya, running asynchronous

PPP. We talk to ‘anyone’ via a T1 CSU/DSU attached to port 0 on a SnapLink. And we connect with

pseudo-one via a PPP connection tunneled across a TCP stream to port 77 on realone.somewhere.com.

If we are unsuccessful at connecting with ‘someone’ we will try again in two seconds. If that attempt fails,

we will wait four seconds before the next attempt; then eight, then sixteen, then thirty two, then forty

seconds. We will continue attempting to contact ‘someone’ every forty seconds. Our retry intervals and

maximum backoff values for ‘everyone’ and ‘nobody’ are the default ‘10-3600’.

The notation "" "" means to expect nothing, then send nothing (followed by a carriage return). The impli-

cit carriage return is often useful for eliciting a response from a remote system.

# Systems - PPP systems file

everyone Any ACU 19200-PEP 5551212 in:--in: Pwe word: \qfoObar

nobody Any ACU 38400 5551213 in:--in: Pthey word: \qbaZz1ng

someone Any;2-40 cua 38400 0 in:--in: Pthem word: \qmeumBle

anyone Any rsd0a/0 1536000

pseudo-one Any;2-2 tcp/realone.somewhere.com/57

RECOMMENDATIONS

The default retry time and backoff (i.e. Any;10-3600) are appropriate for use with dialup connections

where the PPP connection must be reestablished as quickly as possible after an interruption but where it

is not desirable to continuously redial a host that may be down. A much shorter maximum would be

appropriate for a dedicated line between two systems, or where call attempts cost nothing.

Moderate call retry times, such as 60 seconds, work well on systems that can establish connections in

either direction using dialup modems, to avoid deadlocks waiting for telephone busy signals from each

calling the other at the same time. Because of the difference between the behaviors of originating and

answering modems, the 60-second clocks will usually start ticking at different times, allowing one side to

call the other without interference. Alternatively, different call retry times may be speciﬁed at either end

of a link to help keep the two systems from calling each other simultaneously.

If you specify host names, be sure that their addresses are available locally, even with the connection

down. If you ﬁnd that you must bring up a connection to resolve a domain name, consider using that

host’s IP address (decimal numbers separated by periods) in both

Filter and Systems instead.

Automatic failover recovery can be arranged between systems that each have multiple modems, or multi-

ple connection methods. If two systems are connected via a dedicated line (sync or async), that entry

should be ﬁrst in

Systems, followed by another entry describing an on-demand dial-up connection. See

the HP PPP User Guide for more details.

SECURITY CONCERNS

The ﬁle

/etc/ppp/Systems should be mode 600.

AUTHOR

ppp.Systems was developed by the Progressive Systems.