New: max_address parameter is not taken into consideration when IPv6 addresses are created
Subsystems (3)
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Quoted 87 lines · On Wed, 17 Feb 2010 14:12:28 GMT [email protected] wrote:
http://bugzilla.kernel.org/show_bug.cgi?id=15342
Summary:
max_addressparameter is not taken into consideration
when IPv6 addresses are created
Product: Networking
Version: 2.5
Kernel Version: 2.6.32.5
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: low
Priority: P1
Component: IPV6
AssignedTo: [email protected]
ReportedBy: [email protected]
Regression: NoQuoted 1 line
From ip-sysctl.txt file in kernel documentation I can see following description
for
max_addresses:max_addresses- INTEGER
Number of maximum addresses per interface. 0 disables limitation. It is recommended not set too large value (or 0) because it would be too easy way to crash kernel to allow to create too much of autoconfigured addresses.
Default: 16On my machine all parameters are set to default value 16:
# sysctl -a|grep max_addresses net.ipv6.conf.all.max_addresses = 16 net.ipv6.conf.default.max_addresses = 16 net.ipv6.conf.lo.max_addresses = 16 net.ipv6.conf.eth0.max_addresses = 16To my understanding I should not be able to create more than 16 IP addresses, but in fact I am able do it:
# for i in `seq 1 16`; do ip addr add fec0::$i/64 dev eth0; done # ip addr add fec0::17/64 dev eth0 # ip -6 addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000 inet6 fec0::17/64 scope site valid_lft forever preferred_lft forever inet6 fec0::16/64 scope site valid_lft forever preferred_lft forever inet6 fec0::15/64 scope site valid_lft forever preferred_lft forever inet6 fec0::14/64 scope site valid_lft forever preferred_lft forever inet6 fec0::13/64 scope site valid_lft forever preferred_lft forever inet6 fec0::12/64 scope site valid_lft forever preferred_lft forever inet6 fec0::11/64 scope site valid_lft forever preferred_lft forever inet6 fec0::10/64 scope site valid_lft forever preferred_lft forever inet6 fec0::9/64 scope site valid_lft forever preferred_lft forever inet6 fec0::8/64 scope site valid_lft forever preferred_lft forever inet6 fec0::7/64 scope site valid_lft forever preferred_lft forever inet6 fec0::6/64 scope site valid_lft forever preferred_lft forever inet6 fec0::5/64 scope site valid_lft forever preferred_lft forever inet6 fec0::4/64 scope site valid_lft forever preferred_lft forever inet6 fec0::3/64 scope site valid_lft forever preferred_lft forever inet6 fec0::2/64 scope site valid_lft forever preferred_lft forever inet6 fec0::1/64 scope site valid_lft forever preferred_lft forever inet6 fe80::223:aeff:fe77:44ba/64 scope link valid_lft forever preferred_lft foreverIf this parameter applies only for auto-configured IP addressed, please state it more clearly in docs or rename the parameter to show that it refers to auto-configuration.
PATCH 1/1 IPv6: better document max_addresses parameter
Quoted 7 lines · Andrew Morton
Quoted 7 lines
Quoted 1 line
From ip-sysctl.txt file in kernel documentation I can see following description
for
max_addresses:max_addresses- INTEGER
Number of maximum addresses per interface. 0 disables limitation. It is recommended not set too large value (or 0) because it would be too easy way to crash kernel to allow to create too much of autoconfigured addresses.
^^^^^^^^^^^^^^
Quoted 3 lines
Quoted 3 lines
If this parameter applies only for auto-configured IP addressed, please state it more clearly in docs or rename the parameter to show that it refers to auto-configuration.
It did mention autoconfigured in the text, but the below makes it more obvious.
More clearly document IPv6 max_addresses parameter.
---
Documentation/networking/ip-sysctl.txt +4 -4
@@ -1126,10 +1126,10 @@ regen_max_retry - INTEGER Default: 5 max_addresses - INTEGER - Number of maximum addresses per interface. 0 disables limitation. - It is recommended not set too large value (or 0) because it would - be too easy way to crash kernel to allow to create too much of - autoconfigured addresses. + Maximum number of autoconfigured addresses per interface. Setting + to zero disables the limitation. It is not recommended to set this + value too large (or to zero) because it would be an easy way to + crash the kernel by allowing too many addresses to be created. Default: 16 disable_ipv6 - BOOLEAN
Re: [PATCH] IPv6: better document max_addresses parameter
From: Brian Haley <[email protected]>
Date: Mon, 22 Feb 2010 17:27:21 -0500
Quoted 14 lines
Quoted 7 lines · Andrew Morton
Quoted 7 lines
Quoted 1 line
From ip-sysctl.txt file in kernel documentation I can see following description
for
max_addresses:max_addresses- INTEGER
Number of maximum addresses per interface. 0 disables limitation. It is recommended not set too large value (or 0) because it would be too easy way to crash kernel to allow to create too much of autoconfigured addresses.^^^^^^^^^^^^^^Quoted 3 lines
Quoted 3 lines
If this parameter applies only for auto-configured IP addressed, please state it more clearly in docs or rename the parameter to show that it refers to auto-configuration.
Quoted 6 lines
It did mention autoconfigured in the text, but the below makes it more obvious.
More clearly document IPv6
max_addressesparameter.Signed-off-by Brian Haley <[email protected]>
Applied.