On Wed, Mar 15, 2023 at 10:13:50AM +0100, Stefano Brivio wrote:By default, 65520 bytes are advertised, and zero disables DHCP and NDP options. Fixes: ec2b58ea4dc4 ("conf, dhcp, ndp: Fix message about default MTU, make NDP consistent") Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au>--- passt.1 | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/passt.1 b/passt.1 index 6136fa5..4c90634 100644 --- a/passt.1 +++ b/passt.1 @@ -135,8 +135,10 @@ background (if configured to do so). .TP .BR \-m ", " \-\-mtu " " \fImtu -Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5). -By default, no MTU options will be sent. +Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5). A zero value +disables assignment. +By default, the advertised MTU is 65520 bytes, that is, the maximum 802.3 MTU +minus the length of a 802.3 header, rounded to 32 bits (IPv4 words). .TP .BR \-a ", " \-\-address " " \fIaddr-- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson