ebtables

ebtables commmand

• -t, --table

ebtables command has three tables(filter, nat, broute).

* broute: "broute" is a interface which has function, bridge and router.

• -D, --delete
  • usage ex: ebtables -D FORWARD 1 In usage ex, delete an rule, rule num 1 in "FORWARD" table.

if you want to know one in detail, you should look ebtables -h.

• -L, --list

  • usage ex: ebtables -L --Ln

In usage ex, show all chain and all rule.

• -o, --out-interface (interface name)

In my case, output interface is tap device.

* how to make tap device by "openvpn" command.

openvpn –mktun –dev tap –user (username)

* how to be active tap device by "ip" command.

ip link set tap up

• -i, --in-interface (interface name)

• --log

log watcher write description of flame to syslog(/var/log/syslog).

default is log-leve= info , log-prefix="",no ip log, no arp log.

what is ulog?

• --ulog

• --ulog-prefix text

• --ulog-nlgroup group

error

ebtables -A FORWARD --ulog-nlgroup 1 Unable to update the kernel. Two possible causes:

1. Multiple ebtables programs were executing simultaneously. The ebtables userspace tool doesn't by default support multiple ebtables programs running concurrently. The ebtables option --concurrent or a tool like flock can be used to support concurrent scripts that update the ebtables kernel tables.
2. The kernel doesn't support a certain ebtables extension, consider recompiling your kernel or insmod the extension.

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refarence document1

refarence document2

what is netlink?

• nl_group is a bit mask with every bit representing a netlink group number.

refarence document for netlink

usage

• 実行する際には以下のコマンドを実行する必要がある

ebtables -A FORWARD --ulog-nlgroup 1 --ulog-cprange 131072

• 次に以下のソースを実行

./write_tap_v5_hyper 1

• コマンドの第二引数はnlgroupの番号