Package: iputils-ping Version: 3:20161105-1 Severity: normal Tags: ipv6 On IPv4, the -M option controls packet fragmentation, allowing one to detect MTU-related bugs:
$ ping -4 -M do -s 50000 genoa.dictatorshipcake.co.uk PING genoa.dictatorshipcake.co.uk (146.185.142.76) 50000(50028) bytes of data. ping: local error: Message too long, mtu=1450 It seems this option is not effective on IPv6. Even with `-M do` set, I see fragmentation according to tcpdump: $ ping -6 -M do -s 50000 genoa.dictatorshipcake.co.uk PING genoa.dictatorshipcake.co.uk(genoa.dictatorshipcake.co.uk (2a03:b0c0:0:1010::3b7:b001)) 50000 data bytes 50008 bytes from genoa.dictatorshipcake.co.uk (2a03:b0c0:0:1010::3b7:b001): icmp_seq=1 ttl=57 time=62.1 ms causes: 15:10:33.207898 IP6 cel.leo > genoa.dictatorshipcake.co.uk: frag (0|1400) ICMP6, echo request, seq 1, length 1400 15:10:33.207906 IP6 cel.leo > genoa.dictatorshipcake.co.uk: frag (1400|1400) 15:10:33.207908 IP6 cel.leo > genoa.dictatorshipcake.co.uk: frag (2800|1400) 15:10:33.207910 IP6 cel.leo > genoa.dictatorshipcake.co.uk: frag (4200|1400) ... -- System Information: Debian Release: stretch/sid APT prefers testing APT policy: (990, 'testing'), (500, 'unstable') Architecture: amd64 (x86_64) Kernel: Linux 3.16.0-4-amd64 (SMP w/4 CPU cores) Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Init: sysvinit (via /sbin/init) Versions of packages iputils-ping depends on: ii libc6 2.24-8 ii libcap2 1:2.25-1 ii libidn11 1.32-3.1 ii libnettle6 3.2-1 Versions of packages iputils-ping recommends: ii libcap2-bin 1:2.25-1 iputils-ping suggests no packages. -- no debconf information
