核心中不同大小寫的文件

目前複製核心 (094226ad94f4) 會在不區分大小寫的文件系統上產生這些衝突。

 'include/uapi/linux/netfilter/xt_CONNMARK.h'
 'include/uapi/linux/netfilter/xt_connmark.h'
 'include/uapi/linux/netfilter/xt_DSCP.h'
 'include/uapi/linux/netfilter/xt_dscp.h'
 'include/uapi/linux/netfilter/xt_MARK.h'
 'include/uapi/linux/netfilter/xt_mark.h'
 'include/uapi/linux/netfilter/xt_RATEEST.h'
 'include/uapi/linux/netfilter/xt_rateest.h'
 'include/uapi/linux/netfilter/xt_TCPMSS.h'
 'include/uapi/linux/netfilter/xt_tcpmss.h'
 'include/uapi/linux/netfilter_ipv4/ipt_ECN.h'
 'include/uapi/linux/netfilter_ipv4/ipt_ecn.h'
 'include/uapi/linux/netfilter_ipv4/ipt_TTL.h'
 'include/uapi/linux/netfilter_ipv4/ipt_ttl.h'
 'include/uapi/linux/netfilter_ipv6/ip6t_HL.h'
 'include/uapi/linux/netfilter_ipv6/ip6t_hl.h'
 'net/netfilter/xt_DSCP.c'
 'net/netfilter/xt_dscp.c'
 'net/netfilter/xt_HL.c'
 'net/netfilter/xt_hl.c'
 'net/netfilter/xt_RATEEST.c'
 'net/netfilter/xt_rateest.c'
 'net/netfilter/xt_TCPMSS.c'
 'net/netfilter/xt_tcpmss.c'
 'tools/memory-model/litmus-tests/Z6.0+pooncelock+poonceLock+pombonce.litmus'
 'tools/memory-model/litmus-tests/Z6.0+pooncelock+pooncelock+pombonce.litmus'

任何人都可以向我解釋為什麼我們似乎有這些標頭檔的兩個副本，每個標頭檔的名稱略有不同？

所有 Linux 文件系統都區分大小寫，因此預計不會看到 Linux 核心原始碼不區分大小寫。

這些中的每一個都是相似但不相同的程式碼。

例如，這兩個對於相似的概念來說是不同的東西。您可以在核心配置選項之間進行選擇。

比賽版本在xt_hl.c：

IP tables module for matching the value of the TTL
Hop Limit matching module

config NETFILTER_XT_MATCH_HL
tristate '"hl" hoplimit/TTL match support'
depends on NETFILTER_ADVANCED
help
HL matching allows you to match packets based on the hoplimit
in the IPv6 header, or the time-to-live field in the IPv4
header of the packet.

Match 允許編寫 iptables 規則來查找給定的躍點限制。

目標版本在xt_HL.c：

TTL modification target for IP tables
Hop Limit modification target for ip6tables

config NETFILTER_XT_TARGET_HL
tristate '"HL" hoplimit target support'
depends on IP_NF_MANGLE || IP6_NF_MANGLE
depends on NETFILTER_ADVANCED
help
This option adds the "HL" (for IPv6) and "TTL" (for IPv4)
targets, which enable the user to change the
hoplimit/time-to-live value of the IP header.

While it is safe to decrement the hoplimit/TTL value, the
modules also allow to increment and set the hoplimit value of
the header to arbitrary values. This is EXTREMELY DANGEROUS
since you can easily create immortal packets that loop
forever on the network.

Target 添加了對編寫修改數據包跳數限制的 iptables 規則的支持。

由於處理 ip 表和跳數限制，程式碼是相似的。

引用自：https://unix.stackexchange.com/questions/724849