diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/payload-expression.txt | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/doc/payload-expression.txt b/doc/payload-expression.txt index b98a6077..dba42fd5 100644 --- a/doc/payload-expression.txt +++ b/doc/payload-expression.txt @@ -498,6 +498,15 @@ Transport Header, for example TCP ---------------------------------------------- inet filter input meta l4proto {tcp, udp} @th,16,16 { 53, 80 } ----------------------------------------------------------------- +The above can also be written as +----------------------------------------------------------------- +inet filter input meta l4proto {tcp, udp} th dport { 53, 80 } +----------------------------------------------------------------- +it is more convenient, but like the raw expression notation no +dependencies are created or checked. It is the users responsibility +to restrict matching to those header types that have a notion of ports. +Otherwise, rules using raw expressions will errnously match unrelated +packets, e.g. mis-interpreting ESP packets SPI field as a port. .Rewrite arp packet target hardware address if target protocol address matches a given address ---------------------------------------------------------------------------------------------- |