catch iptables logs from container to host












0














I'm trying to catch the logs generated by iptables running inside a container.
Since LOG support is disabled for container (see here), I'm trying to set the iptables log rules in the host.
I'm testing it with a rule (on the host) that catches a SYN scan from NMap (*1).



So the idea is to set iptables rules on host to log scans performed against a container (named c_victim), which is using a virtual bridged interface br-a1b2c3 (*2).



I've tried different rules similar to:



# iptables -I FORWARD -m physdev --physdev-out veth144i0 --physdev-is-bridged -j LOG --log-prefix "[fw::test]"


where veth144i0 is the virtual ethernet interface associated to br-a1b2c3 (*3). I got this rule from here.
None of the rules I tried generated logs in my host after checking with:



$ journalctl -b | grep "[fw.*]"


Any ideas on how to set the iptables rule in (*1) for a container??





(*1): Just to make sure that the rule works, I tested it in my host:



# iptables -I INPUT -p tcp -m multiport --dports 23,79 --tcp-flags ALL SYN -m limit --limit 3/m --limit-burst 5 -j LOG --log-prefix "[fw::syn-scan] "


then scanned the host from a container with:



root@887952fed115# nmap -sS 192.168.0.14


and then checked the logs with:



$ journalctl -b | grep "[fw.*]"


where the logs of the scan appear ok.





(*2): I know this because I checked using a combination of these commands:



$ docker container inspect c_victim | grep NetworkID 
$ docker network ls
$ ifconfig -a




(*3): I checked this by looking at the symlinks:



ls -l /sys/devices/virtual/net/veth*/master




As exploratory checks, I also set the rules (in host always):



# iptables -I FORWARD -i br-a1b2c3 -j LOG --log-prefix "[fw::test-in]"
# iptables -I FORWARD -o br-a1b2c3 -j LOG --log-prefix "[fw::test-out]"


to see what happens, and this is what I get:




  • no logs are generated if I scan the container from the host.

  • only the first one generates logs in my journalctl if I scan the host from the container c_victim.










share|improve this question



























    0














    I'm trying to catch the logs generated by iptables running inside a container.
    Since LOG support is disabled for container (see here), I'm trying to set the iptables log rules in the host.
    I'm testing it with a rule (on the host) that catches a SYN scan from NMap (*1).



    So the idea is to set iptables rules on host to log scans performed against a container (named c_victim), which is using a virtual bridged interface br-a1b2c3 (*2).



    I've tried different rules similar to:



    # iptables -I FORWARD -m physdev --physdev-out veth144i0 --physdev-is-bridged -j LOG --log-prefix "[fw::test]"


    where veth144i0 is the virtual ethernet interface associated to br-a1b2c3 (*3). I got this rule from here.
    None of the rules I tried generated logs in my host after checking with:



    $ journalctl -b | grep "[fw.*]"


    Any ideas on how to set the iptables rule in (*1) for a container??





    (*1): Just to make sure that the rule works, I tested it in my host:



    # iptables -I INPUT -p tcp -m multiport --dports 23,79 --tcp-flags ALL SYN -m limit --limit 3/m --limit-burst 5 -j LOG --log-prefix "[fw::syn-scan] "


    then scanned the host from a container with:



    root@887952fed115# nmap -sS 192.168.0.14


    and then checked the logs with:



    $ journalctl -b | grep "[fw.*]"


    where the logs of the scan appear ok.





    (*2): I know this because I checked using a combination of these commands:



    $ docker container inspect c_victim | grep NetworkID 
    $ docker network ls
    $ ifconfig -a




    (*3): I checked this by looking at the symlinks:



    ls -l /sys/devices/virtual/net/veth*/master




    As exploratory checks, I also set the rules (in host always):



    # iptables -I FORWARD -i br-a1b2c3 -j LOG --log-prefix "[fw::test-in]"
    # iptables -I FORWARD -o br-a1b2c3 -j LOG --log-prefix "[fw::test-out]"


    to see what happens, and this is what I get:




    • no logs are generated if I scan the container from the host.

    • only the first one generates logs in my journalctl if I scan the host from the container c_victim.










    share|improve this question

























      0












      0








      0







      I'm trying to catch the logs generated by iptables running inside a container.
      Since LOG support is disabled for container (see here), I'm trying to set the iptables log rules in the host.
      I'm testing it with a rule (on the host) that catches a SYN scan from NMap (*1).



      So the idea is to set iptables rules on host to log scans performed against a container (named c_victim), which is using a virtual bridged interface br-a1b2c3 (*2).



      I've tried different rules similar to:



      # iptables -I FORWARD -m physdev --physdev-out veth144i0 --physdev-is-bridged -j LOG --log-prefix "[fw::test]"


      where veth144i0 is the virtual ethernet interface associated to br-a1b2c3 (*3). I got this rule from here.
      None of the rules I tried generated logs in my host after checking with:



      $ journalctl -b | grep "[fw.*]"


      Any ideas on how to set the iptables rule in (*1) for a container??





      (*1): Just to make sure that the rule works, I tested it in my host:



      # iptables -I INPUT -p tcp -m multiport --dports 23,79 --tcp-flags ALL SYN -m limit --limit 3/m --limit-burst 5 -j LOG --log-prefix "[fw::syn-scan] "


      then scanned the host from a container with:



      root@887952fed115# nmap -sS 192.168.0.14


      and then checked the logs with:



      $ journalctl -b | grep "[fw.*]"


      where the logs of the scan appear ok.





      (*2): I know this because I checked using a combination of these commands:



      $ docker container inspect c_victim | grep NetworkID 
      $ docker network ls
      $ ifconfig -a




      (*3): I checked this by looking at the symlinks:



      ls -l /sys/devices/virtual/net/veth*/master




      As exploratory checks, I also set the rules (in host always):



      # iptables -I FORWARD -i br-a1b2c3 -j LOG --log-prefix "[fw::test-in]"
      # iptables -I FORWARD -o br-a1b2c3 -j LOG --log-prefix "[fw::test-out]"


      to see what happens, and this is what I get:




      • no logs are generated if I scan the container from the host.

      • only the first one generates logs in my journalctl if I scan the host from the container c_victim.










      share|improve this question













      I'm trying to catch the logs generated by iptables running inside a container.
      Since LOG support is disabled for container (see here), I'm trying to set the iptables log rules in the host.
      I'm testing it with a rule (on the host) that catches a SYN scan from NMap (*1).



      So the idea is to set iptables rules on host to log scans performed against a container (named c_victim), which is using a virtual bridged interface br-a1b2c3 (*2).



      I've tried different rules similar to:



      # iptables -I FORWARD -m physdev --physdev-out veth144i0 --physdev-is-bridged -j LOG --log-prefix "[fw::test]"


      where veth144i0 is the virtual ethernet interface associated to br-a1b2c3 (*3). I got this rule from here.
      None of the rules I tried generated logs in my host after checking with:



      $ journalctl -b | grep "[fw.*]"


      Any ideas on how to set the iptables rule in (*1) for a container??





      (*1): Just to make sure that the rule works, I tested it in my host:



      # iptables -I INPUT -p tcp -m multiport --dports 23,79 --tcp-flags ALL SYN -m limit --limit 3/m --limit-burst 5 -j LOG --log-prefix "[fw::syn-scan] "


      then scanned the host from a container with:



      root@887952fed115# nmap -sS 192.168.0.14


      and then checked the logs with:



      $ journalctl -b | grep "[fw.*]"


      where the logs of the scan appear ok.





      (*2): I know this because I checked using a combination of these commands:



      $ docker container inspect c_victim | grep NetworkID 
      $ docker network ls
      $ ifconfig -a




      (*3): I checked this by looking at the symlinks:



      ls -l /sys/devices/virtual/net/veth*/master




      As exploratory checks, I also set the rules (in host always):



      # iptables -I FORWARD -i br-a1b2c3 -j LOG --log-prefix "[fw::test-in]"
      # iptables -I FORWARD -o br-a1b2c3 -j LOG --log-prefix "[fw::test-out]"


      to see what happens, and this is what I get:




      • no logs are generated if I scan the container from the host.

      • only the first one generates logs in my journalctl if I scan the host from the container c_victim.







      docker networking iptables virtual-network






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 13 '18 at 2:17









      issrcissrc

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