| bpf.4 (13744) | bpf.4 (18715) |
|---|---|
| 1.\" Copyright (c) 1990 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that: (1) source code distributions 6.\" retain the above copyright notice and this paragraph in its entirety, (2) 7.\" distributions including binary code include the above copyright notice and 8.\" this paragraph in its entirety in the documentation or other materials --- 6 unchanged lines hidden (view full) --- 15.\" written permission. 16.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 17.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 18.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 19.\" 20.\" This document is derived in part from the enet man page (enet.4) 21.\" distributed with 4.3BSD Unix. 22.\" | 1.\" Copyright (c) 1990 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that: (1) source code distributions 6.\" retain the above copyright notice and this paragraph in its entirety, (2) 7.\" distributions including binary code include the above copyright notice and 8.\" this paragraph in its entirety in the documentation or other materials --- 6 unchanged lines hidden (view full) --- 15.\" written permission. 16.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 17.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 18.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 19.\" 20.\" This document is derived in part from the enet man page (enet.4) 21.\" distributed with 4.3BSD Unix. 22.\" |
| 23.\" $Id$ 24.\" |
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| 23.Dd January 16, 1996 24.Dt BPF 4 25.Os BSD 4.4 26.Sh NAME 27.Nm bpf 28.Nd Berkeley Packet Filter 29.Sh SYNOPSIS 30.Cd pseudo-device bpfilter --- 273 unchanged lines hidden (view full) --- 304.El 305.Pp 306The 307.Li bh_hdrlen 308field exists to account for 309padding between the header and the link level protocol. 310The purpose here is to guarantee proper alignment of the packet 311data structures, which is required on alignment sensitive | 25.Dd January 16, 1996 26.Dt BPF 4 27.Os BSD 4.4 28.Sh NAME 29.Nm bpf 30.Nd Berkeley Packet Filter 31.Sh SYNOPSIS 32.Cd pseudo-device bpfilter --- 273 unchanged lines hidden (view full) --- 306.El 307.Pp 308The 309.Li bh_hdrlen 310field exists to account for 311padding between the header and the link level protocol. 312The purpose here is to guarantee proper alignment of the packet 313data structures, which is required on alignment sensitive |
| 312architectures and and improves performance on many other architectures. | 314architectures and improves performance on many other architectures. |
| 313The packet filter insures that the 314.Li bpf_hdr 315and the network layer 316header will be word aligned. Suitable precautions 317must be taken when accessing the link layer protocol fields on alignment 318restricted machines. (This isn't a problem on an Ethernet, since 319the type field is a short falling on an even offset, 320and the addresses are probably accessed in a bytewise fashion). --- 398 unchanged lines hidden --- | 315The packet filter insures that the 316.Li bpf_hdr 317and the network layer 318header will be word aligned. Suitable precautions 319must be taken when accessing the link layer protocol fields on alignment 320restricted machines. (This isn't a problem on an Ethernet, since 321the type field is a short falling on an even offset, 322and the addresses are probably accessed in a bytewise fashion). --- 398 unchanged lines hidden --- |