Hello,

I have been messing with my diald/ppp setup and I have a strange
problem.  Basically everything works fine, that is, when I try to use
some command that needs the net, my modem dials in and off I go.  diald
will then hang up after a specified time of inactivity.  This I believe
is controlled by the file /etc/diald/standard.filters.

I have been using dctrl to look at timeouts and noticed that although my
general tcp timeout is set to 10 minutes, fetchmail generates tcp
packets that start as though they'd keep the link up for 10 minutes, but
after about 1 second it changes to keeping the link up for only 5
seconds.  If the host that fetchmail is trying to connect is not in my
/etc/hosts, then everything still works since the host query udp packets
have 30 second timeouts.  (My modem takes about 20 seconds to connect.)

I am using partially upgraded Debian 1.2.  In particular, diald is in
version 0.16.4-7, and ppp is 2.2.0f-23.

I included a copy of my /etc/diald/standard.filters in case it's
relevant.

I'd be glad to hear your insights,

Janos.

# This is a pretty complicated set of filter rules.
# (These are the rules I use myself.)
#
# I've divided the rules up into four sections.
# TCP packets, UDP packets, ICMP packets and a general catch all rule
# at the end.


#------------------------------------------------------------------------------
# Rules for TCP packets.
#------------------------------------------------------------------------------
# General comments on the rule set:
#
# In general we would like to treat only data on a TCP link as signficant
# for timeouts. Therefore, we try to ignore packets with no data.
# Since the shortest possible set of headers in a TCP/IP packet is 40 bytes.
# Any packet with length 40 must have no data riding in it.
# We may miss some empty packets this way (optional routing information
# and other extras may be present in the IP header), but we should get
# most of them. Note that we don't want to filter out packets with
# tcp.live clear, since we use them later to speedup disconnects
# on some TCP links.
#
# We also want to make sure WWW packets live even if the TCP socket
# is shut down. We do this because WWW doesn't keep connections open
# once the data has been transfered, and it would be annoying to have the link
# keep bouncing up and down every time you get a document.
#
# Outside of WWW the most common use of TCP is for long lived connections,
# that once they are gone mean we no longer need the network connection.
# We don't neccessarily want to wait 10 minutes for the connection
# to go down when we don't have any telnet's or rlogin's running,
# so we want to speed up the timeout on TCP connections that have
# shutdown. We do this by catching packets that do not have the live flag set.

# --- start of rule set proper ---

# When initiating a connection we only give the link 15 seconds initially.
# The idea here is to deal with possibility that the network on the opposite
# end of the connection is unreachable. In this case you don't really
# want to give the link 10 minutes up time. With the rule below
# we only give the link 15 seconds initially. If the network is reachable
# then we will normally get a response that actually contains some
# data within 15 seconds. If this causes problems because you have a slow
# response time at some site you want to regularly access, you can either
# increase the timeout or remove this rule.
accept tcp 15 tcp.syn

# Keep named xfers from holding the link up
ignore tcp tcp.dest=tcp.domain
ignore tcp tcp.source=tcp.domain

# (Ack! SCO telnet starts by sending empty SYNs and only opens the
# connection if it gets a response. Sheesh..)
accept tcp 5 ip.tot_len=40,tcp.syn

# keep empty packets from holding the link up (other than empty SYN packets)
ignore tcp ip.tot_len=40,tcp.live

# make sure http transfers hold the link for 2 minutes, even after they end.
# NOTE: Your /etc/services may not define the tcp service www, in which
# case you should comment out the following two lines or get a more
# up to date /etc/services file. See the FAQ for information on obtaining
# a new /etc/services file.
#####accept tcp 120 tcp.dest=tcp.www
#####accept tcp 120 tcp.source=tcp.www
# make it 10 minutes for more sluggish viewers
accept tcp 600 tcp.dest=tcp.www
accept tcp 600 tcp.source=tcp.www

# Once the link is no longer live, we try to shut down the connection
# quickly. Note that if the link is already down, a state change
# will not bring it back up.
keepup tcp 5 !tcp.live
ignore tcp !tcp.live

# an ftp-data or ftp connection can be expected to show reasonably frequent
# traffic.
accept tcp 120 tcp.dest=tcp.ftp
accept tcp 120 tcp.source=tcp.ftp

#NOTE: ftp-data is not defined in the /etc/services file provided with
# the latest versions of NETKIT, so I've got this commented out here.
# If you want to define it add the following line to your /etc/services:
# ftp-data        20/tcp
# and uncomment the following two rules.
#####accept tcp 120 tcp.dest=tcp.ftp-data
#####accept tcp 120 tcp.source=tcp.ftp-data
# make it 10 minutes for slower people
accept tcp 600 tcp.dest=tcp.ftp-data
accept tcp 600 tcp.source=tcp.ftp-data

# If we don't catch it above, give the link 10 minutes up time.
accept tcp 600 any

# Rules for UDP packets
#
# We time out domain requests right away, we just want them to bring
# the link up, not keep it around for very long.
# This is because the network will usually come up on a call
# from the resolver library (unless you have all your commonly
# used addresses in /etc/hosts, in which case you will discover
# other problems.)
# Note that you should not make the timeout shorter than the time you
# might expect your DNS server to take to respond. Otherwise
# when the initial link gets established there might be a delay
# greater than this between the initial series of packets before
# any packets that keep the link up longer pass over the link.

# Don't bring the link up for rwho.
ignore udp udp.dest=udp.who
ignore udp udp.source=udp.who
# Don't bring the link up for RIP.
ignore udp udp.dest=udp.route
ignore udp udp.source=udp.route
# Don't bring the link up for NTP or timed.
ignore udp udp.dest=udp.ntp
ignore udp udp.source=udp.ntp
ignore udp udp.dest=udp.timed
ignore udp udp.source=udp.timed
# Don't bring up on domain name requests between two running nameds.
ignore udp udp.dest=udp.domain,udp.source=udp.domain
# Bring up the network whenever we make a domain request from someplace
# other than named.
accept udp 30 udp.dest=udp.domain 
accept udp 30 udp.source=udp.domain
# Do the same for netbios-ns broadcasts
# NOTE: your /etc/services file may not define the netbios-ns service
# in which case you should comment out the next three lines.
ignore udp udp.source=udp.netbios-ns,udp.dest=udp.netbios-ns
accept udp 30 udp.dest=udp.netbios-ns
accept udp 30 udp.source=udp.netbios-ns
# keep routed and gated transfers from holding the link up
ignore udp tcp.dest=udp.route
ignore udp tcp.source=udp.route
# Anything else gest 2 minutes.
accept udp 120 any

# Catch any packets that we didn't catch above and give the connection
# 30 seconds of live time.
#####accept any 30 any
# Try 4 minutes instead
accept any 240 any


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