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UTM Blocks reply packet

Pete01


Hi All,

I have a strange behaviour in the UTM packet filter.
We have an incoming connection which we have allowed as usual with this rule.

FW Rule:
Src: 172.24.nnn.nnn/16
DST: 10.0.bbb.bbb/24
TCP: 443

Incoming connections work, but the reply from 10.0.bbb.bbb:443 seems be to a new connection, as without allowing the 10.0.bbb.bbb:443 > 172.nnn.nnn.nnn:50243 the UTM blocks the reply.


08:07:03.081547 IP 172.nnn.nnn.nnn.50243 > 10.0.bbb.bbb.443: Flags [.], ack 28151, win 255, length 0
08:07:03.082191 IP 172.nnn.nnn.nnn.50243 > 10.0.bbb.bbb.443: Flags [P.], seq 61065:61356, ack 28151, win 255, length 291
08:07:03.082239 IP 172.nnn.nnn.nnn.50243 > 10.0.bbb.bbb.5080: Flags [P.], seq 61356:61719, ack 28151, win 255, length 363
08:07:03.082255 IP 10.0.bbb.bbb.5080 > 172.nnn.nnn.nnn.50243: Flags [.], ack 61719, win 1452, length 0
08:07:03.082597 IP 10.0.bbb.bbb.5080 > 172.nnn.nnn.nnn.50243: Flags [P.], seq 28151:28408, ack 61719, win 1452, length 257
08:07:03.082653 IP 10.0.bbb.bbb.5080 > 172.nnn.nnn.nnn.50243: Flags [P.], seq 28408:28415, ack 61719, win 1452, length 7


    Default DROP    TCP         10.0.bbb.bbb    :    443
    →    172.nnn.nnn.nnn    :    50243
         [RST]    len=40    ttl=63    tos=0x00    srcmac=7c:cccccccccc    dstmac=00

    Default DROP    TCP         10.0.bbb.bbb    :    443
    →    172.nnn.nnn.nnn    :    50243
         [RST]    len=40    ttl=63    tos=0x00    srcmac=7c:cccccccc    dstmac=00




Any Hint what’s going on there?

Greetings



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  • 0

    Do you see any problems with the connection?
    The dropped packet is a "RST" Packet. This means "TCP session reset".
    This packet often  is send some time after session is timed out ...  If server and client don't close the TCP session properly.
    Normally everything works ... with these packets within FW-log.


    Dirk

    Systema Gesellschaft für angewandte Datentechnik mbH  // Sophos Platinum Partner
    Sophos Solution Partner since 2003
    If a post solves your question, click the 'Verify Answer' link at this post.

Reply
  • 0

    Do you see any problems with the connection?
    The dropped packet is a "RST" Packet. This means "TCP session reset".
    This packet often  is send some time after session is timed out ...  If server and client don't close the TCP session properly.
    Normally everything works ... with these packets within FW-log.


    Dirk

    Systema Gesellschaft für angewandte Datentechnik mbH  // Sophos Platinum Partner
    Sophos Solution Partner since 2003
    If a post solves your question, click the 'Verify Answer' link at this post.

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