--- jonen/notes/notes_2003-02.twingle 2003/03/09 16:36:37 1.1 +++ jonen/notes/notes_2003-02.twingle 2003/03/09 16:43:24 1.2 @@ -41,23 +41,25 @@ x use packet fiters (firewall): x read http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/firewalls.html x some options at the kernel have to be enabled: -
- options IPFIREWALL #Compiles into the kernel the code for packet filtering. - options IPFIREWALL_VERBOSE #Enables code to allow logging of packets through syslogd. - # Without this option, even if you specify that packets should be logged in the filter rules, - # nothing will happen. - options IPFIREWALL_VERBOSE_LIMIT=10 #Limits the number of packets logged through syslogd on a per entry basis. - # You may wish to use this option in hostile environments in which you want to log firewall activity, - # but do not want to be open to a denial of service attack via syslog flooding. - # When a chain entry reaches the packet limit specified, logging is turned off for that particular entry. - # To resume logging, you will need to reset the associated counter using the ipfw(8) utility: - # ipfw zero 4500 - # Where 4500 is the chain entry you wish to continue logging. - options IPFIREWALL_DEFAULT_TO_ACCEPT #This changes the default rule action from ``deny'' to ``allow''. - # This avoids the possibility of locking yourself out if you happen to boot a kernel with IPFIREWALL support but have not configured your firewall yet. - # It is also very useful if you often use ipfw(8) as a filter for specific problems as they arise. - # Use with care though, as this opens up the firewall and changes the way it works. -+ - options IPFIREWALL + Compiles into the kernel the code for packet filtering. + - options IPFIREWALL_VERBOSE + Enables code to allow logging of packets through syslogd. + Without this option, even if you specify that packets should be logged in the filter rules, + nothing will happen. + - options IPFIREWALL_VERBOSE_LIMIT=10 + Limits the number of packets logged through syslogd on a per entry basis. + You may wish to use this option in hostile environments in which you want to log firewall activity, + but do not want to be open to a denial of service attack via syslog flooding. + When a chain entry reaches the packet limit specified, logging is turned off for that particular entry. + To resume logging, you will need to reset the associated counter using the ipfw(8) utility: + :# ipfw zero 4500 + Where 4500 is the chain entry you wish to continue logging. + - options IPFIREWALL_DEFAULT_TO_ACCEPT + This changes the default rule action from ``deny'' to ``allow''. + This avoids the possibility of locking yourself out if you happen to boot a kernel with IPFIREWALL support but have not configured your firewall yet. + It is also very useful if you often use ipfw(8) as a filter for specific problems as they arise. + Use with care though, as this opens up the firewall and changes the way it works. x firewall is enabled at /etc/rc.conf (or /etc/rc.conf.local) firewall_enabled = "YES" firewall_type = "