Hello!
Well-known thing is abusive use of ping abillity to fill out the ICMP
packet with '+++ATH0', which will cause hangup on 'bad' modems.
The
defense, at the clinet side, is to add 'S2=255' to modem settings.
This 'technique' is used in irc wars, and other abusive attacks, and
shell
providers have a lot of problems with that. There are two ways to forbid
users of doing all those 'hangups'. First, is to close outgoing pings,
and
second one is to disallow using ping with -p option (wrapper, directly in
code, etc). But, -p option could be useful for diagnosing data-dependent
problems in a network, so better solution is to log usings of ping -p
option.
This little patch (in attachment) will enable logging via syslogd(8).
Messages are logged with 'warrning' priority, and consist of PID, UID,
pattern, and pinged target. Patch is made for netkit-base-0.10, a part of
Slackware, and other distributions too.
Sincerely,
Bosko
[mod: Logging at the ISP will not help people who have a decent
machine/modem from pinging others. People who are annoyed by others
shutting down their link can specify "escape 41 61" to have ppp escape
all A's before transmission. (Untested: my link didn't hangup when I
tried it...) -- REW ]
