diff options
author | Angelos D. Keromytis <angelos@cvs.openbsd.org> | 2001-07-05 09:04:04 +0000 |
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committer | Angelos D. Keromytis <angelos@cvs.openbsd.org> | 2001-07-05 09:04:04 +0000 |
commit | 1a1b7b490a3552db79a9bc6aa95a2de2faf5b30a (patch) | |
tree | 557f117892de7042d6da9047ce7239d4e7e599ac | |
parent | 95aa48ab6043a7658e975f79ccae90e78fe7094b (diff) |
Syntax, style, wording.
-rw-r--r-- | share/man/man4/ipcomp.4 | 81 |
1 files changed, 46 insertions, 35 deletions
diff --git a/share/man/man4/ipcomp.4 b/share/man/man4/ipcomp.4 index f2ce9705cbf..dc7fddcb51b 100644 --- a/share/man/man4/ipcomp.4 +++ b/share/man/man4/ipcomp.4 @@ -1,4 +1,4 @@ -.\" $OpenBSD: ipcomp.4,v 1.1 2001/07/05 08:57:16 jjbg Exp $ +.\" $OpenBSD: ipcomp.4,v 1.2 2001/07/05 09:04:03 angelos Exp $ .\" .\" Copyright (c) 2001 Jean-Jacques Bernard-Gundol <jj@wabbitt.org> .\" All rights reserved. @@ -46,61 +46,71 @@ variable in .Pp .Sh DESCRIPTION .Tn IPComp -is a protocol used to reduce the size of IP datagrams. It can be used -to enhance the communication performance between a pair of -hosts/gateways, especially on slow links, by compressing the datagrams, -provided the communicating entities have enough computation power. +is a protocol used to reduce the size of IP datagrams. +It can be used to enhance the communication performance between a pair +of hosts/gateways, especially on slow links, by compressing the +datagrams, provided the communicating entities have enough computation +power. .Pp This protocol is especially useful when encryption or authentication is applied to IP datagrams using the .Tn IPsec protocol (see .Xr ipsec 4 -for more information about IPsec). Encrypting information is -increasing its entropy to a point where compression to a lower layer -become completely useless (i.e PPP Compression Control -Protocol). IPcomp is applied at the network layer before other -encryption operations are applied (except encryption protocols applied -at a higher layer such as ssh or ssl). +for more information about IPsec). +Encrypting information is increasing its entropy to a point where +compression to a lower layer become completely useless (i.e PPP +Compression Control Protocol). +IPcomp is applied at the network layer before other encryption +operations are applied (except encryption protocols applied at a +higher layer such as +.Xr ssh 1 +or +.Xr ssl 8 ). .Pp -Just like for the IPsec protocols, IPComp needs some parameters for -each connection, telling how the compression should be done between -the entities. The parameters are collected are collected in a -structure called an IPComp Association or IPCA. The parameters stored -in an IPCA are: the destination address and the Compression Parameter -Index (CPI). An IPCA is the pendant of the SA (Security Association) -for IPsec. +Just like for the othre IPsec protocols, IPComp needs some parameters +for each connection, specifying how the compression should be done +between the entities. +The parameters are collected are collected in a structure called an +IPComp Association or IPCA. +The parameters stored in an IPCA are the destination address and the +Compression Parameter Index (CPI). +An IPCA is the pendant of the SA (Security Association) for IPsec. .Pp Currently, IPCA can be created using the .Xr ipsecadm 8 -tool. Using +tool. +Using .Xr ipsecadm 8 it is also possible to create IPComp flows and bundled -SA/IPCA. Such a bundle is used to create a combination of IPsec and -IPComp flows (thus enabling compression in an IPsec protocol). +SA/IPCA. +Such a bundle is used to create a combination of IPsec and IPComp +flows (thus enabling compression in an IPsec protocol). .Pp The compression is done on the data following the IP header and an IPComp header is inserted between the compressed data and the IP -header. In the case of IPv6, there are extension headers which cannot be +header. +In the case of IPv6, there are extension headers which cannot be compressed since they are modified by the router along the way to the -destination. These extension headers are hop-by-hop, routing, and -fragmentation. +destination. +These extension headers are hop-by-hop, routing, and fragmentation. .Pp When doing compression, it is possible that compressed data is smaller -in size than non compressed one. To avoid this behaviour, a non -expansion policy is used in IPComp. If the data payload is smaller -than a given threshold, it will not be compressed. No IPComp header -will be inserted. +in size than non compressed one. +To avoid this behaviour, a non expansion policy is used in IPComp. +If the data payload is smaller than a given threshold, it will not be +compressed. +No IPComp header will be inserted. .Pp Just like for IPsec, the implementation is using the virtual interface .Nm enc0 which can be used in packet filters to specify packets that are -allowed to be processed by IPComp. But since IPsec and IPComp are both -using this interface, special care must be taken when using a bundle -SA/IPCA. +allowed to be processed by IPComp. +But since IPsec and IPComp are both using this interface, special care +must be taken when using a bundle SA/IPCA. .Pp -IPComp is using the same policy framework than IPsec. However unlike -IPsec, only one policy is available for IPComp: +IPComp is using the same policy framework as IPsec. +However unlike IPsec, only one policy is available for IPComp: .Bl -tag -width IPSEC_LEVEL_USE .It IPSEC_LEVEL_USE Use IPComp for sending packets but still accept packets which are not @@ -110,7 +120,8 @@ compressed. .Xr netstat 1 can be used to obtain some statistics about IPComp usage, using the .Fl p -flag. Just like for IPsec, using the +flag. +Just like for IPsec, using the .Fl r flag, .Xr netstat 1 @@ -126,7 +137,7 @@ displays information about IPComp flows. The .Nm protocol first appeared in -.Ox 2.9 . +.Ox 3.0 . .Sh AUTHOR The support for the .Nm |