For more information regarding the security incident at F5, the actions we are taking to address it, and our ongoing efforts to protect our customers, click here.

Forum Discussion

Anesh's avatar
Anesh
Icon for Cirrostratus rankCirrostratus
May 27, 2014

Connection table entry removed after idle timer reaches tcp keep alive value

Problem: i am doing a telnet to a VIP configured on an LTM and the Connection table entry removed after idle timer reaches tcp keep alive value configured which is 60 seconds and also the i see the idle time counter resetting to zero which is expected My question is why is the connection table entry removed??

 

Below is LTM Config

 

ltm virtual testvip { destination 6.6.6.6:9041 ip-protocol tcp mask 255.255.255.255 persist source_addr { Default yes} pool testpool profiles tcp_test snat automap

 

}

 

ltm profile tcp tcp_test {app-service none defaults-from tcp-lan-optimized keep-alive-interval 60 }

 

19 Replies

  • Anesh's avatar
    Anesh
    Icon for Cirrostratus rankCirrostratus

    can you check the config from your end, i think it is a bug, bcoz when i filter by sequence number the FIN is being sent by the pool member in response to the ACK(tcp-keep-alive) sent by the floating self ip of the LTM

     

  • can you check the config from your end, i think it is a bug, bcoz when i filter by sequence number the FIN is being sent by the pool member in response to the ACK(tcp-keep-alive) sent by the floating self ip of the LTM

     

    if you believe it is a bug, you may open a support case and ask them to verify.

     

  • Can you send tcp-keep-alive on a https port

     

    no, i cannot hold clientside connection long enough to get keep-alive packet.

     

  • Anesh's avatar
    Anesh
    Icon for Cirrostratus rankCirrostratus
    ltm profile tcp tcp_test {
    app-service none 
    defaults-from tcp-lan-optimized 
    keep-alive-interval 60 
    }
    

    So when i apply the above custom tcp profile with pool members listening on a HTTPS port it will not work?... is that right?

  • So when i apply the above custom tcp profile with pool members listening on a HTTPS port it will not work?.

     

    why does it not work?

     

  • Anesh's avatar
    Anesh
    Icon for Cirrostratus rankCirrostratus

    the Pool member responds with a FIN/ACK when the ACK is sent by the f5

     

  • Anesh's avatar
    Anesh
    Icon for Cirrostratus rankCirrostratus
    No.     Time                Source                Destination           Protocol Info
        280 2014-05-27 15:37:20 6.6.6.6         1.1.1.1         TCP      [TCP Keep-Alive] 9041 > 57703 [ACK] Seq=2629992488 Ack=144158763 Win=65535 Len=0
    
    
    No.     Time                Source                Destination           Protocol Info
        281 2014-05-27 15:37:20 3.3.3.3         2.2.2.2          TCP      [TCP Keep-Alive] 57703 > 9041 [ACK] Seq=380327577 Ack=1111550497 Win=65535 Len=0
    
    
    No.     Time                Source                Destination           Protocol Info
        282 2014-05-27 15:37:20 2.2.2.2          3.3.3.3         TCP      [TCP Window Update] 9041 > 57703 [ACK] Seq=1111550497 Ack=380327578 Win=46 Len=0
    
    
    No.     Time                Source                Destination           Protocol Info
        283 2014-05-27 15:37:20 1.1.1.1         6.6.6.6         TCP      [TCP Keep-Alive ACK] 57703 > 9041 [ACK] Seq=144158763 Ack=2629992489 Win=68 Len=0
    
    
    No.     Time                Source                Destination           Protocol Info
        284 2014-05-27 15:37:22 2.2.2.2          3.3.3.3         TCP      9041 > 57703 [FIN, ACK] Seq=1111550497 Ack=380327578 Win=46 Len=0
    
    
    No.     Time                Source                Destination           Protocol Info
        285 2014-05-27 15:37:22 3.3.3.3         2.2.2.2          TCP      57703 > 9041 [ACK] Seq=380327578 Ack=1111550498 Win=4380 Len=0
    
    
    No.     Time                Source                Destination           Protocol Info
        286 2014-05-27 15:37:22 6.6.6.6         1.1.1.1         TCP      9041 > 57703 [FIN, ACK] Seq=2629992489 Ack=144158763 Win=3780 Len=0
    
    
    No.     Time                Source                Destination           Protocol Info
        287 2014-05-27 15:37:22 1.1.1.1         6.6.6.6         TCP      57703 > 9041 [ACK] Seq=144158763 Ack=2629992490 Win=68 Len=0
    
    
    No.     Time                Source                Destination           Protocol Info
        288 2014-05-27 15:37:22 1.1.1.1         6.6.6.6         TCP      57703 > 9041 [FIN, ACK] Seq=144158763 Ack=2629992490 Win=68 Len=0
    
    
    No.     Time                Source                Destination           Protocol Info
        289 2014-05-27 15:37:22 6.6.6.6         1.1.1.1         TCP      9041 > 57703 [ACK] Seq=2629992490 Ack=144158764 Win=3780 Len=0
    
    
    
    6.6.6.6---VIP
    2.2.2.2---Pool member
    3.3.3.3---snat
    1.1.1.1---client