Date: Wed, 15 Jul 2020 14:27:25 +0000 From: bugzilla-noreply@freebsd.org To: net@FreeBSD.org Subject: [Bug 248002] ping(8): TTL DETAILS update Message-ID: <bug-248002-7501@https.bugs.freebsd.org/bugzilla/>
next in thread | raw e-mail | index | archive | help
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D248002 Bug ID: 248002 Summary: ping(8): TTL DETAILS update Product: Documentation Version: Latest Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: Manual Pages Assignee: bugs@FreeBSD.org Reporter: jlduran@gmail.com CC: doc@FreeBSD.org, net@FreeBSD.org Reading ping(8), section "TTL DETAILS", I have seen a number of inconsistencies regarding this value in FreeBSD. This section of the man p= age has not been updated to reflect the current state. For instance: > Not change it; this is what BSD systems did before the 4.3BSD-Tahoe relea= se. > In this case the TTL value in the received packet will be 255 minus the > number of routers in the round-trip path. This paragraph implies that FreeBSD is still using 255 as its default TTL, it should be updated to reflect the current value (64) [1], perhaps: Not change it; this is what BSD systems did before the 4.3BSD-Tahoe release. In this case the TTL value in the received packet will be 64 minus the numb= er of routers in the round-trip path. Other paragraphs could also be updated, for example: > The TCP/IP specification recommends setting the TTL field for IP packets = to > 64, but many systems use smaller values (4.3BSD uses 30, 4.2BSD used 15). The TCP/IP specification recommends setting the TTL field for IP packets to 64, FreeBSD uses this value... The DESCRIPTION mentions that the sysctl net.inet.ip.ttl is used, but it does not say that this value is 64 by default. Maybe also include some current OSs? I have compiled a quick list that can = be easily verified pinging the hosts inside the brackets, this should give you the TTL (plus the number of hops): Windows: 128 [live.com] BSDs (NetBSD and OpenBSD): 255 [netbsd.org, openbsd.org] Linux: 64 [linux.org] FreeBSD, macOS: 64 > Set it to 255; this is what current BSD systems do. In this case the TTL > value in the received packet will be 255 minus the number of routers in t= he > path from the remote system to the pinging host. Set it to 255; this is what some BSD systems do... Some current BSD systems do use 255 (at least NetBSD and OpenBSD); however, FreeBSD uses the IANA-recommended value of 64 [2]. References: [1]=20 https://github.com/freebsd/freebsd/blob/3f4da6d3e7a2a8cc34a94938bd1c4f80c8d= 1d449/sys/netinet/ip.h#L212 [2]=20 https://www.iana.org/assignments/ip-parameters/ip-parameters.xhtml#ip-param= eters-2 --=20 You are receiving this mail because: You are on the CC list for the bug.=
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?bug-248002-7501>