On Wed, 2009-11-04 at 09:03 -0600, Jason Barrett wrote:
  

Balazs Scheidler wrote: 
    

On Fri, 2009-10-30 at 14:23 -0500, Jason Barrett wrote:
  
      

Hi all,

I'm relaying log messages from one syslog-ng server to another.  At the 
final stop, the only way I can get the $HOST macro to work is if I 
enable dns resolution on server 1.  Is this by design?  Here are the 
relevant configs:

----------------------------------------------------------------------

syslog-ng server 1 (relays to server 2):
chain_hostnames(yes);
keep_hostname(yes);
use_dns(no);

source s_udp { udp(port(514)); };
destination df_udpback { udp("192.168.1.157" port(514)); };
log { source(s_udp); destination(df_udpback); };

----------------------------------------------------------------------

syslog-ng server 2:
chain_hostnames(yes);
keep_hostname(yes);
use_dns(yes);

source s_udp { udp(port(514)); };
destination df_udp { file("/var/log/ics/$HOST/$YEAR/$MONTH/$DAY"); };
log { source(s_udp); destination(df_udp); };

----------------------------------------------------------------------

Sample log message on server 2:
Oct 30 09:35:03 10.12.24.46/10.12.24.46 %ASA-5-111005: 10.28.22.55 end 
configuration: OK

10.12.24.46 is the correct IP address of the originating host, and $HOST 
resolves to this IP address.  I would prefer $HOST to resolve to the 
hostname as it exists in the /etc/hosts file.
    
        

$HOST always resolves to the "HOST" portion of the syslog message.

syslog-ng can resolve only from /etc/hosts if you use these global
options:

options { use-dns(persist-only) dns-cache-hosts('/etc/hosts'); };

  
      

"$HOST always resolves to the "HOST" portion of the syslog message."

So if the syslog message's host field contains an IP Address, $HOST will always resolve to the IP address regardless of the use-dns setting?
    

that depends on the keep-hostname() setting. It works like this

* message comes in with something in its "HOST" field, the message may
lack a hostname in which case syslog-ng _always_ adds one.
* syslog-ng decides whether it should trust the hostname field
(keep-hostname is set to yes it will trust it, if set to no it will not)
* if keep-hostname() is set to no, then syslog-ng will rewrite the HOST
field, possibly using DNS use-dns(yes)

Anything that refers to the HOST macro is done after this rewrite is
complete.