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rahrahruby
Asked: 2012-04-07 13:22:41 +0800 CST

iptables logging to diferent file via syslog-ng

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I have the following configuration in my iptables and syslog files:

IPTABLES

-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 222 -j ACCEPT

-A INPUT -p tcp -m tcp --dport 3306 -j ACCEPT

-A INPUT -j DROP

-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7

SYSLOG-NG

destination d_iptables { file("/var/log/iptables/iptables.log"); };

filter f_iptables { facility(kern) and match("IN=" value("MESSAGE")) and match("OUT=" value("MESSAGE")); };

filter f_messages { level(info,notice,warn) and
                    not facility(auth,authpriv,cron,daemon,mail,news) and not 
filter(f_iptables); };

log { source(s_src); filter(f_iptables); destination(d_iptables); };`

I restart syslog-ng and the log is not written.

syslog-ng

2 Answers

  1. Ok, after a lot of pain I finally got it working, here is the final config, I hope it helps someone.

    iptables

        :INPUT ACCEPT [0:0]
    :FORWARD ACCEPT [0:0]
    :LOGNDROP - [0:0]
    :OUTPUT ACCEPT [63:18352]
    -A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7
    -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT 
    -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT 
    -A INPUT -p tcp -m tcp --dport 222 -j ACCEPT 
    -A INPUT -p tcp -m tcp --dport 3306 -j ACCEPT 
    -A INPUT -s 85.25.146.0/24 -j DROP 
    -A INPUT -j DROP

    syslog.confg

    destination d_iptables { file("/var/log/iptables.log"); };
filter f_iptables { match("iptables denied" value("MESSAGE")); };
filter f_debug { level(debug) and not facility(auth, authpriv, news, mail) and not filter(f_iptables); };
#       not facility(auth,authpriv,cron,daemon,mail,news) and not filter(f_iptables); };
filter f_kern { facility(kern) and not filter(f_iptables); };
log { source(s_src); filter(f_iptables); destination(d_iptables); };
    • 3
  2. Best Answer

    Your syslog-ng config appears fine to me but your iptables config isn't. The -j LOG line appears after a line that DROPs everything, hence it will never be reached.

    You should move the LOG line to directly before whatever event you want to log. If you want to log everything, put it first. If you want to log everything that isn't ACCEPTed, put it after all the ACCEPTs.

    • 2