удобный редактор пакетов (user-friendly packet editor action)
Имя (Name)
skbmod - user-friendly packet editor action
Синопсис (Synopsis)
tc ... action skbmod { set SETTABLE | swap SWAPPABLE } [ CONTROL
] [ index INDEX ]
SETTABLE := [ dmac DMAC ] [ smac SMAC ] [ etype ETYPE ]
SWAPPABLE := mac
CONTROL := { reclassify | pipe | drop | shot | continue | pass }
Описание (Description)
The skbmod action is intended as a usability upgrade to the
existing pedit action. Instead of having to manually edit 8-,
16-, or 32-bit chunks of an ethernet header, skbmod allows
complete substitution of supported elements.
Параметры (Options)
dmac DMAC
Change the destination mac to the specified address.
smac SMAC
Change the source mac to the specified address.
etype ETYPE
Change the ethertype to the specified value.
mac Used to swap mac addresses.
CONTROL
The following keywords allow to control how the tree of
qdisc, classes, filters and actions is further traversed
after this action.
reclassify
Restart with the first filter in the current list.
pipe Continue with the next action attached to the same
filter.
drop
shot Drop the packet.
continue
Continue classification with the next filter in
line.
pass Finish classification process and return to calling
qdisc for further packet processing. This is the
default.
Примеры (Examples)
To start, observe the following filter with a pedit action:
tc filter add dev eth1 parent 1: protocol ip prio 10 \
u32 match ip protocol 1 0xff flowid 1:2 \
action pedit munge offset -14 u8 set 0x02 \
munge offset -13 u8 set 0x15 \
munge offset -12 u8 set 0x15 \
munge offset -11 u8 set 0x15 \
munge offset -10 u16 set 0x1515 \
pipe
Using the skbmod action, this command can be simplified to:
tc filter add dev eth1 parent 1: protocol ip prio 10 \
u32 match ip protocol 1 0xff flowid 1:2 \
action skbmod set dmac 02:15:15:15:15:15 \
pipe
Complexity will increase if source mac and ethertype are also
being edited as part of the action. If all three fields are to be
changed with skbmod:
tc filter add dev eth5 parent 1: protocol ip prio 10 \
u32 match ip protocol 1 0xff flowid 1:2 \
action skbmod \
set etype 0xBEEF \
set dmac 02:12:13:14:15:16 \
set smac 02:22:23:24:25:26
Finally, swap the destination and source mac addresses in the
header:
tc filter add dev eth3 parent 1: protocol ip prio 10 \
u32 match ip protocol 1 0xff flowid 1:2 \
action skbmod \
swap mac
However, trying to set and swap in a single skbmod command will
cause undefined behavior.
Смотри также (See also)
tc(8), tc-u32(8), tc-pedit(8)
