This module sets the Type of Service field in the IPv4 header (including the "precedence" bits) or the Priority field in the IPv6 header. Note that TOS shares the same bits as DSCP and ECN. The TOS target is only valid in the mangle table.

--set-tos value[/mask]
    Zeroes out the bits given by mask and XORs value into the TOS/Priority field. If mask is omitted, 0xFF is assumed.

--set-tos symbol
    You can specify a symbolic name when using the TOS target for IPv4. It implies a mask of 0xFF. The list of recognized TOS names can be obtained by calling iptables with -j TOS -h.

The following mnemonics are available:

--and-tos bits
    Binary AND the TOS value with bits. (Mnemonic for --set-tos 0/invbits, where invbits is the binary negation of bits.)

--or-tos bits
    Binary OR the TOS value with bits. (Mnemonic for --set-tos bits/bits.)

--xor-tos bits
    Binary XOR the TOS value with bits. (Mnemonic for --set-tos bits/0.)