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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2006-01-03 10:58:34 +0000 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2006-01-03 10:58:34 +0000 |
| commit | 56185b42e77e6841bd76fbfff27e7c57855f88f6 (patch) | |
| tree | 52c058ebb6dd63eae8f7c032b9ebbf2b6540fb38 /man7/icmp.7 | |
| parent | d6d5023908d5626e524662b7e024476a3e13c6f7 (diff) | |
| download | man-pages-56185b42e77e6841bd76fbfff27e7c57855f88f6.tar.gz | |
Formatting and source code line break changes (no changes to content!)
Diffstat (limited to 'man7/icmp.7')
| -rw-r--r-- | man7/icmp.7 | 34 |
1 files changed, 19 insertions, 15 deletions
diff --git a/man7/icmp.7 b/man7/icmp.7 index 9bf75c620d..3b61380ebc 100644 --- a/man7/icmp.7 +++ b/man7/icmp.7 @@ -8,12 +8,13 @@ .SH NAME icmp, IPPROTO_ICMP \- Linux IPv4 ICMP kernel module. .SH DESCRIPTION -This kernel protocol module implements the Internet Control Message Protocol -defined in RFC\ 792. It is used to signal error conditions and for diagnosis. -The user doesn't interact directly with this module; instead it communicates -with the other protocols in the kernel and these pass the ICMP -errors to the application layers. The kernel ICMP module also -answers ICMP requests. +This kernel protocol module implements the Internet Control +Message Protocol defined in RFC\ 792. +It is used to signal error conditions and for diagnosis. +The user doesn't interact directly with this module; +instead it communicates with the other protocols in the kernel +and these pass the ICMP errors to the application layers. +The kernel ICMP module also answers ICMP requests. .PP A user protocol may receive ICMP packets for all local sockets by opening a raw socket with the protocol @@ -37,16 +38,19 @@ The sysctls can be accessed by reading or writing the .I /proc/sys/net/ipv4/* files or with the .BR sysctl (2) -interface. Most of these sysctls are rate limitations for specific ICMP types. +interface. +Most of these sysctls are rate limitations for specific ICMP types. Linux 2.2 uses a token bucket filter to limit ICMPs. .\" FIXME better description needed -The value is the timeout in jiffies until the token bucket filter is cleared -after a burst. A jiffy is a system dependent unit, usually 10ms on x86 and +The value is the timeout in jiffies until the token bucket filter is +cleared after a burst. +A jiffy is a system dependent unit, usually 10ms on x86 and about 1ms on alpha and IA64. .TP .B icmp_destunreach_rate -Maximum rate to send ICMP Destination Unreachable packets. This limits the -rate at which packets are sent to any individual route or destination. +Maximum rate to send ICMP Destination Unreachable packets. +This limits the rate at which packets are sent to any individual +route or destination. The limit does not affect sending of .B ICMP_FRAG_NEEDED packets needed for path MTU discovery. @@ -90,15 +94,15 @@ should not be relied on in portable programs. .PP .B ICMP_REDIRECT packets are not sent when Linux is not acting as a router. -They are also only accepted from the old gateway defined in the routing table and -the redirect routes are expired after some time. +They are also only accepted from the old gateway defined in the +routing table and the redirect routes are expired after some time. .PP The 64-bit timestamp returned by .B ICMP_TIMESTAMP is in milliseconds since January 1, 1970. .PP -Linux ICMP internally uses a raw socket to send ICMPs. This raw socket -may appear in +Linux ICMP internally uses a raw socket to send ICMPs. +This raw socket may appear in .BR netstat (8) output with a zero inode. .PP |