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v18: Bug with data counting in firewall rules?

cryptochrome

Hi,

I am noticing a strange behavior in v18 and the data counting in the firewall rules. I have some incoming rules (from Internet to DMZ) that are coupled with corresponding DNAT rules. The DMZ contains webservers, so they send a lot more data than they receive. However, the counters in the rules are the other way around: They show a lot more incoming data than outgoing data. 

Unless I am completely misinterpreting these counters (which I would like to rule out), it appears to me these counters have been reversed, e.g. incoming is actually showing outgoing, and outgoing is showing incoming. 

Any thoughts?



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  • 0 in reply to cryptochrome

    I fully agree with . Lucar yours response is not helpful!

    If this is an issue, must be addressed and fixed. I guess that the counters are written inside postgres so I do not want to imagine that even the reports are wrong.

    Regards

  • 0 in reply to cryptochrome

    All the firewall has to do is look at who initiated the connection. If the server in the DMZ initiates a connection through an interface, it's outgoing traffic. If the server responds to a connection, it's incoming traffic. 

     
    That is how XG performs the Traffic logging.  
    NAT is not the issue, it is the definition of Zone concept. The Firewall with IN/OUT as "Terms" causing this misleading terms. 
     

    We are counting the Traffic after processing the Traffic through all modules. It is about to Leave the destination Interface and gets tracked.

     

    Important is the Traffic Initiator, as you said. 

     

     

    LAN to WAN. IN means Download (Send by the XG LAN Interface / WAN Server). OUT means Upload (Send by the XG WAN Interface / LAN Client). 

    WAN to DMZ. IN means Download (Send by the XG WAN Interface / DMZ Server). OUT means Upload (Send by the XG DMZ Interface / WAN Client) 

     

     

    LAN to WAN:

    Download Scenario: Client sends 5 Bytes to XG. Server sends 10 MB to XG.  XG Sends 5 Bytes to Server, XG Sends 10 MB to the Client. 

    From XG Perspective: 

    Firewall: IN 10 MB, OUT 5 Bytes. 

    Firewall: Sent 10 MB to the Client, Sent 5 Bytes to the Server. 

    Firewall: Gets 10 MB from the Server, Gets 5 Bytes from the Client.

    Firewall: Downloads 10 MB from the Server, Uploads 5 Bytes to the Server.

    Firewall: Downloads 5 Bytes from the Client, Uploads 10 MB to the Server.  

     

     

     

    DNAT Scenario:

    Download Scenario: WebClient sends 5 Bytes to XG. DMZ Server sends 10 MB to XG.  

    Firewall: IN 10 MB, OUT, 5 Bytes. 

    Firewall: Sent 10 MB to the WebClient, Sent 5 Bytes to the DMZ Server. 

    Firewall: Gets 10 MB from the DMZ Server, Gets 5 Bytes from the WebClient.

    Firewall: Downloads 10 MB from the DMZ Server, Uploads 5 Bytes to the  DMZ Server.

    Firewall: Downloads 5 Bytes from the WebClient, Uploads 10 MB to the WebClient.  

     

     

    It is more likely a perspective issue. 

     

    Looking at the Plex Issue.

    Plex Client is in the WAN. 

    Plex Server is in the DMZ. 

     

    Client is building the Connection to Plex Server.

    Starting to Stream a Movie. 

    Client requests the Movie, sending 5 MB. 

    Server sending the Movie to the Client, Sending 10 GB. 

    Firewall: IN 10 GB, OUT, 5 MB. 

    Firewall: Sent 10 GB to the Plex Client, Sent 5 MB to the Plex Server. 

    Firewall: Gets 10 GB from the Plex Server, Gets 5 MB from the Plex Client.

    Firewall: Downloads 10 GB from the Plex Server, Uploads 5 MB to the  Plex Server.

    Firewall: Downloads 5 MB from the Plex Client, Uploads 10 GB to the Plex Client.  

     

     

     

    XG Firewall Tracking does everything correct, from my point of view. 

     

     

    Maybe remove IN/OUT as Terms? You would have: 10 GB / 5 MB for example. 

     

     

     

    *edit* 

    Lets take another example:

    Client to DMZ. 

    Client downloads a file from my DMZ Server.

    IN would be the Traffic send by my Server.

    OUT would be the traffic send by my Client. 

     

    Thats how it works since the beginning. 

    Now the same is done by DNAT + Firewall. 

    Basically XG did not Change anything in his firewall behavior for NAT. It is simply another Client to Server concept. 

  • 0 in reply to LuCar Toni

    LuCar Toni said:

    It is more likely a perspective issue. 

     

     
    Maybe. And just to be clear: I completely understand what you are saying, but I think your perspective is still wrong. It's overly complicated, illiogical, entirely disregards the concept of TCP/IP session initiation (from which you must derive traffic direction) and goes against what any other firewall vendor is doing. As a matter of fact, it goes against what every vendor of any kind of network device is doing. 
     
    Just to make sure, it must not matter whether a connection is subject to NAT. All that matters is who is initiating the connection. From that perspective, session initiator is always IN, and session responder is always OUT. 
     
    To stay with your example on Plex:
     
    Plex Client initiates connection to Plex Server (sends 50 KB of data, requesting playback of movie). Plex Server ACKnowledges session, responds with 10 GB of data. Firewall is stateful, sees which side is initiating (SYN) and which side is responding (SYN ACK). Hence, Plex Client is INcoming traffic, Plex Server is OUTgoing traffic. 
     
    If the Plex Server would terminate the client session and then establish a new session back to the client to send the movie, your logic would be correct. But that's not how it works. 
     
    To be frank, I don't understand why we even have to discuss this, given the fact that XG does it correctly for all connections, except when NAT is in place (which changes absolutely nothing in terms of session establishment). This has to be looked at from a network perspective and a user perspective, not from a developer's perspective. 
     
  • 0 in reply to cryptochrome
    Plex Client initiates connection to Plex Server (sends 50 KB of data, requesting playback of movie). Plex Server ACKnowledges session, responds with 10 GB of data. Firewall is stateful, sees which side is initiating (SYN) and which side is responding (SYN ACK). Hence, Plex Client is INcoming traffic, Plex Server is OUTgoing traffic. 
     
    XG uses the Client Perspective. Hence it uses the terms of IN and OUT from the Client perspective. (Initiator). 
    Plex Client traffic is OUTgoing Traffic, because the initiator sends this traffic.
    Plex Server traffic is INcoming Traffic, because the recipient sends this traffic. 
     
    That is how XG does it for years and nobody was asking to change it. 
     
    Now in the setup of the DNAT, it could be misleading. DNAT gives us the setup, that the Initiator is NOT behind XG, instead the recipient is behind XG. 
     
     
    I am actually not sure, how V17.5 (Business App Rules) used to work. 
  • 0 in reply to LuCar Toni

    LuCar Toni said:
     
    XG uses the Client Perspective. Hence it uses the terms of IN and OUT from the Client perspective. (Initiator). 
     

     
    Well that perspective is wrong. Especially given the fact that you use this perspective only on DNAT traffic, but not on SNAT traffic (where you actually do it correctly). Totally inconsistent. 
     
    LuCar Toni said:
     
    Plex Client traffic is OUTgoing Traffic, because the initiator sends this traffic.
    Plex Server traffic is INcoming Traffic, because the recipient sends this traffic. 
     
    That is how XG does it for years and nobody was asking to change it. 
     
     
    As you can see, I am not the only one who is confused about this weird perspective of looking at things. This is probably coming from a developer's mindset, not one of a network engineer's. 
     
    LuCar Toni said:
     
    Now in the setup of the DNAT, it could be misleading. DNAT gives us the setup, that the Initiator is NOT behind XG, instead the recipient is behind XG. 
     
     
    Right. And this should be changed. If DNAT is "misleading" the firewall's data collection, then it's a bug. 
     
    Just to re-iterate, when there is no DNAT in place, the XG actually does it right. The traffic directions are correct in all cases except when DNAT is applied. 
  • 0 in reply to cryptochrome

    V17.5 Client to Server through DNAT.

    Upload Something:

     

    Download something:

     

    Same behavior like V18. 

     

    Just to re-iterate, when there is no DNAT in place, the XG actually does it right. The traffic directions are correct in all cases except when DNAT is applied.

     

    Actually that is not true.

    LAN to WAN. Download shown as IN Bytes.

    DMZ to WAN. Download shown as IN Bytes.

    WAN to DMZ(DNAT). Download shown as IN Bytes. 

     

     

    The Plex Scenario shows this perfectly. 

    If the Client is in LAN, Plex in DMZ, streaming a Movie shows the movie as IN Bytes. 

    If the Client is in WAN, Plex in DMZ, Streaming a Movie shows the movie as IN Bytes. 

     

     

     

    Just to be complete.

    Client - XG1 SNAT - Internet - XG2 DNAT - Server 

    Client Upload:

    XG1 (SNAT):

    XG2 (DNAT):

     

     

    Client Download something:

    XG1 (SNAT):

    XG2 (DNAT):

     

     

    I am not sure, why this discussion comes up "now". 

    This traffic logging is in the product like this forever.

     

  • 0 in reply to LuCar Toni

    LuCar Toni said:

    V17.5 Client to Server through DNAT.

    Same behavior like V18. 

    I am talking about v18, not v17. If v17 has done it like this that's fine, I never noticed and hence didn't care. Now with v18 I noticed. 

    LuCar Toni said:
     

    Actually that is not true.

    LAN to WAN. Download shown as IN Bytes.

    DMZ to WAN. Download shown as IN Bytes.

    WAN to DMZ(DNAT). Download shown as IN Bytes. 

    You're still not grasping the concept of session initiation. It doesn't matter which interface combination (LAN to WAN or the other way around). The only thing that matters is who initiated the connection. You can't seem to wrap your head around it because you keep thinking about this from the client perspective you are used to. But it's wrong. Try to think outside the box. In your WAN to DMZ (DNAT) example above, the client (WAN) is downloading from a server in the DMZ, I assume. The server is sending data TO the client, OUT the WAN interface through the DMZ interface. The only thing that the traffic direction must be derived from is the session initiator. You send data TO the initiator, you send data OUT. You receive data FROM the initiator, data is coming IN. It's really as simple as that. 

     

    If you just want to be right and think the way Sophos XG is doing it now, that's fine. It's still illogical and inconsistent, because the behavior is different between SNAT and DNAT (and yes, that is actually true, at least that's what I see here on v18). 

  • 0 in reply to cryptochrome

    Updated my post above.  

    Client is always the session initiator. Hence we are using In for traffic going to the Session initiator in all perspectives, no matter if NAT or not. 

    Proved it via Screenshots. 

     

    XG act like it should act, always collecting the session initiator and summarize the traffic as IN to the initiator, and OUT coming from the initiator. 

     

    I assume there is nothing wrong with this way to deal with it. 

  • 0 in reply to LuCar Toni

    , 

    can you investigate on the issue inside?

  • +2 in reply to LuCar Toni

    You haven't proven anything other than not understanding, sorry. Client is NOT always the session initiator. You're factually wrong. And just because you always did it like this doesn't make it right. There are two other people in this thread who are as confused about this as I am.

    And yes, you are actually doing it differently when DNAT is applied. Here is my "prove". This is a firewall rule for access to the internet, where users predominantly download stuff from the internet (hence, they are the session initiators). The rule is subject to SNAT(MASQ). It correctly shows most data as incoming and only little data as outgoing, as expected:

    This is a firewall rule that has a corresponding DNAT rule. It shows that the server in the DMZ is sending very little data and it looks like the server is downloading a lot (IN), but it's actually the other way around, the server is SENDING a lot of data to people on the internet (who are the session initiators). The numbers are reversed:

    So there you have it, it is clearly and obviously different when DNAT is in place.

    Don't assume you are right. Consider you might be wrong. Other people in this thread agree.