skb_checksum_complete(9) [suse man page]

SKB_CHECKSUM_COMPLET(9) 					 Linux Networking					   SKB_CHECKSUM_COMPLET(9)

NAME

       skb_checksum_complete - Calculate checksum of an entire packet

SYNOPSIS

       __sum16 skb_checksum_complete(struct sk_buff * skb);

ARGUMENTS

       skb
	   packet to process

DESCRIPTION

       This function calculates the checksum over the entire packet plus the value of skb->csum. The latter can be used to supply the checksum of
       a pseudo header as used by TCP/UDP. It returns the checksum.

       For protocols that contain complete checksums such as ICMP/TCP/UDP, this function can be used to verify that checksum on received packets.
       In that case the function should return zero if the checksum is correct. In particular, this function will return zero if skb->ip_summed is
       CHECKSUM_UNNECESSARY which indicates that the hardware has already verified the correctness of the checksum.

COPYRIGHT

Kernel Hackers Manual 2.6.					     July 2010						   SKB_CHECKSUM_COMPLET(9)

LO(4)							   BSD Kernel Interfaces Manual 						     LO(4)

NAME

     lo -- software loopback network interface

SYNOPSIS

     device loop

DESCRIPTION

     The loop interface is a software loopback mechanism which may be used for performance analysis, software testing, and/or local communication.
     As with other network interfaces, the loopback interface must have network addresses assigned for each address family with which it is to be
     used.  These addresses may be set with the appropriate ioctl(2) commands for corresponding address families.  The loopback interface should
     be the last interface configured, as protocols may use the order of configuration as an indication of priority.  The loopback should never be
     configured first unless no hardware interfaces exist.

     If the transmit checksum offload capability flag is enabled on a loopback interface, checksums will not be generated by IP, UDP, or TCP for
     packets sent on the interface.

     If the receive checksum offload capability flag is enabled on a loopback interface, checksums will not be validated by IP, UDP, or TCP for
     packets received on the interface.

     By default, both receive and transmit checksum flags will be enabled, in order to avoid the overhead of checksumming for local communication
     where data corruption is unlikely.  If transmit checksum generation is disabled, then validation should also be disabled in order to avoid
     packets being dropped due to invalid checksums.

DIAGNOSTICS

     lo%d: can't handle af%d.  The interface was handed a message with addresses formatted in an unsuitable address family; the packet was
     dropped.

SEE ALSO

     inet(4), intro(4)

HISTORY

     The lo device appeared in 4.2BSD.	The current checksum generation and validation avoidance policy appeared in FreeBSD 8.0.

BSD
								 January 25, 2012							       BSD