That explanation was very helpful and insightful. Thank you sir. We may be at a misunderstanding of what I mean about vulnerability scanner events. What is happening is the vulnerability scanners in our environment are scanning all ports across my syslog servers. The scanners connection attempts or vulnerability tests are being written to disc as events. Which in turn end up in my logging system and are just noise I don't need.
So yeah you're right it is a bit of an overengineering issue, but I don't really have a choice. Either I find a way to drop traffic from specific sources to all of my open ports for our syslog only. Or I just use IP tables and block the scanners altogether, as you suggested earlier.... Unfortunately that means I'd have to do manual vulnerability checks on my servers, and I really don't want to have to deal with that, hahaha Regards, Steven. -------- Original message -------- From: Mariusz Kruk <k...@epsilon.eu.org> Date: 12/9/22 8:19 AM (GMT-05:00) To: Steven D <pheerl...@hotmail.com>, rsyslog@lists.adiscon.com Subject: Re: [rsyslog] "Global" fromhost-ip blocklist? Depends on what you means by "processed". It is read from the main config (default or explicitly specified in command line) and if there is any include directive, the corresponding file(s) is getting inserted in this spot. So you end up with an "effective config" which you can see with "-o fullconf" option. This config is intepreted (we're still talking about reading config, not processing events!) from the top to bottom so that for most things if you have some dependency, it must be defined earlier (like you must have a lookup defined earlier in the config to be able to call that lookup later). Then comes the part of event processing - if some operation is not defined within a specific ruleset it's assumed to be in an implicit "main" ruleset. And similarily - if an input is not associated with a specific ruleset, events received by that input are processed by that implicit main ruleset. BTW, if you're planning on just dropping the events from the vulnerability scanners you could just drop events on this one port but I don't know your precise circumstances. It's just that it seems that you're trying to overengineer something that could be much simpler ;-) MK On 9.12.2022 13:15, Steven D wrote: Thanks for all the input, ok so some answers inline Nope - So this looks straight forward to me, but correct some ignorance on my end. The way you've defined the "syslogtag" rulesets, it makes me assume that the syslog config processed in a top down manner, otherwise logically it doesn't work. Is that true? The way we have our syslog config set up is to group all the related template/ruleset/input stanzas together... Just from an ease of modification PoV it makes it easier. Kurk Mariusz - I don't have control over the sending hosts, they are vulnerability scanners that indiscriminately scan the environment. I can't just iptable drop those same devices from touching the syslog servers as that will cause other operational issues. ________________________________ From: rsyslog <rsyslog-boun...@lists.adiscon.com><mailto:rsyslog-boun...@lists.adiscon.com> on behalf of Mariusz Kruk via rsyslog <rsyslog@lists.adiscon.com><mailto:rsyslog@lists.adiscon.com> Sent: Friday, December 9, 2022 5:30 AM To: rsyslog@lists.adiscon.com<mailto:rsyslog@lists.adiscon.com> <rsyslog@lists.adiscon.com><mailto:rsyslog@lists.adiscon.com> Cc: Mariusz Kruk <k...@epsilon.eu.org><mailto:k...@epsilon.eu.org> Subject: Re: [rsyslog] "Global" fromhost-ip blocklist? I know that it has already been answered but let me add my three cents ;-) Firstly, adding condition to $fromhost-ip suggests that you want to limit based on the source IP, not on the event's content. Which raises the question - why not simply _not_ send from that host? Or at least filter it out on the local firewall (most probably iptables). Secondly, expanding on nope's response - you can have multiple rulesets chained together so that you have some common "subroutine" and then branch to specific ruleset depending on how you want to process given source or data type. You can use lookups or conditions to dynamically decide to which ruleset you want to route your event to. The possibilities are endless :-) (and you can end up creating a ruleset loop and crashing your rsyslogd XD) Something like. ruleset(name="ruleset1") { set $.destination_ruleset="dest1"; call intermediate_ruleset } ruleset(name="ruleset2") { set $.destination_ruleset="dest2"; call intermediate_ruleset } ruleset(name="intermediate_ruleset") { set $.this=$that; // and other stuff call_indirect $.destination_ruleset; } ruleset(name="dest1") { ... } ruleset(name="dest2") { ... } MK On 8.12.2022 16:15, Steven D via rsyslog wrote: > Rsyslog gurus > > I have a config that accepts connections from remote hosts and steers logs to > files based on port. Pretty straightforward... what i'm looking to do is > "globally" prevent certain ip addresses from ending up in the logs. (Internal > vulnerability scanners I have no control over). > > I've tried a few different ways but not coming across anything that works > globally. Adding something like "if $fromhost-ip '1.2.3.4' then stop" works > just fine on an individual ruleset. > > Is there a way I can do this without having to enter duplicate lines in every > ruleset (I have like 30 rulesets) ? > > Thanks, > Steven > > Config snippet below: "#logname01/02#" is replaced by the relevant product in > the configuration. > > module(load="imudp") > module(load="imtcp" MaxListeners="100" AddtlFrameDelimiter="000" > KeepAlive="on" KeepAlive.Probes="1" KeepAlive.Time="10") > > input(type="imudp" port="24514" ruleset="#logname01#_rule") > input(type="imtcp" port="24514" ruleset="#logname01#_rule") > template(name="#logname01#_logs" type="string" > string="/data/logs/#logname01#/24514/%fromhost-ip%/syslog.log") > ruleset(name="#logname01#_rule") { > action(name="#logname01#_rule" > type="omfile" > FileCreateMode="0744" > DirCreateMode="0755" > FileOwner="SIEM" > FileGroup="SIEM" > DirOwner="SIEM" > DirGroup="SIEM" > DynaFile="#logname01#_logs" > DynaFileCacheSize = "50") > } > > input(type="imudp" port="25514" ruleset="#logname02#_rule") > input(type="imtcp" port="25514" ruleset="#logname02#_rule") > template(name="#logname02#_logs" type="string" > string="/data/logs/#logname02#/25514/%fromhost-ip%/syslog.log") > ruleset(name="#logname02#_rule") { > action(name="#logname02#_rule" > type="omfile" > FileCreateMode="0744" > DirCreateMode="0755" > FileOwner="SIEM" > FileGroup="SIEM" > DirOwner="SIEM" > DirGroup="SIEM" > DynaFile="#logname02#_logs" > DynaFileCacheSize = "50") > } > > _______________________________________________ > rsyslog mailing list > https://lists.adiscon.net/mailman/listinfo/rsyslog > http://www.rsyslog.com/professional-services/ > What's up with rsyslog? Follow https://twitter.com/rgerhards > NOTE WELL: This is a PUBLIC mailing list, posts are ARCHIVED by a myriad of > sites beyond our control. PLEASE UNSUBSCRIBE and DO NOT POST if you DON'T > LIKE THAT. _______________________________________________ rsyslog mailing list https://lists.adiscon.net/mailman/listinfo/rsyslog http://www.rsyslog.com/professional-services/ What's up with rsyslog? Follow https://twitter.com/rgerhards NOTE WELL: This is a PUBLIC mailing list, posts are ARCHIVED by a myriad of sites beyond our control. PLEASE UNSUBSCRIBE and DO NOT POST if you DON'T LIKE THAT. _______________________________________________ rsyslog mailing list https://lists.adiscon.net/mailman/listinfo/rsyslog http://www.rsyslog.com/professional-services/ What's up with rsyslog? Follow https://twitter.com/rgerhards NOTE WELL: This is a PUBLIC mailing list, posts are ARCHIVED by a myriad of sites beyond our control. PLEASE UNSUBSCRIBE and DO NOT POST if you DON'T LIKE THAT.
