SnapGear 1.7.8 Manuel D’Utilisation

Appendix B – System Log 

Access Logging 

It is possible to log any traffic that arrives at or traverses the SnapGear appliance.  The 
only logging that is enabled by default is to take note of packets that were dropped.  
While it is possible to specifically log exactly which rule led to such a drop, this is not 
configured by default.  All rules in the default security policy drop packets.  They never 
reject them.  That is, the packets are simply ignored, and have no responses at all 
returned to the sender.  It is possible to configure reject rules if so desired. 

All traffic logging performed on the SnapGear appliance creates entries in the syslog 
(/var/log/messages - or external syslog server) of the following format: 

<Date/Time> klogd: <prefix> IN=<incoming interface> OUT=<outgoing 
interface> MAC=<dst/src MAC addresses> SRC=<source IP> 

DST=<destination IP> SPT=<source port> DPT=<destination port> 
<additional packet info> 

Where: 

<prefix>     if non-empty, hints at cause for log entry 

<incoming interface> 

will be empty, or one of eth0, eth1 and similar 

     

as per incoming interface 

     

<dst/src MAC addresses>  MAC addresses associated with the packet 

     

packet claims it came from this IP address 

     

packet claims it should go to this IP address 

     

<source port> 

 

packet claims it came from this TCP port 

     

packet wants to go to this TCP port 

Depending on the type of packet and logging performed some of the fields may not 
appear.