Milen Rangelov wrote:
>I know that good IP filtering on the sysklogd box is the best fix, but
>always resolving hostnames of the log messages' sender is definitely not
>a good idea..
>
>
That's why you should use syslog-ng instead. With it you can tweak all
the DNS parameters (see below) and create filters to drop unwanted log
messages.
>From syslog-ng.conf man page:
use_dns(yes|no)
Enable or disable DNS usage. syslog-ng blocks on DNS
queries, so enabling DNS may lead to a
Denial of Service attack. To prevent DoS, protect your
syslog-ng network endpoint with fire-
wall rules, and make sure that all hosts, which may get to
syslog-ng is resolvable.
use_fqdn(yes|no)
Add Fully Qualified Domain Name instead of short hostname.
check_hostname(yes|no)
Enable or disable whether the hostname contains valid
characters.
bad_hostname(regex)
A regexp which matches hostnames which should not be taken
as such.
dns_cache(yes|no)
Enable or disable DNS cache usage.
dns_cache_expire(n)
Number of seconds while a successful lookup is cached.
dns_cache_expire_failed(n)
Number of seconds while a failed lookup is cached.
dns_cache_size(n)
Number of hostnames in the DNS cache.
Hth.
--
Christophe Garault
