From 1acff721a3874a74efc9921a1e07bd48bd7efab0 Mon Sep 17 00:00:00 2001 From: Michael Tremer Date: Tue, 22 Feb 2022 12:07:15 +0000 Subject: [PATCH] Allow free selection of MTU by the user Various ISPs (or equipment?) seem to hand out an MTU of only 576 bytes. Hwoever, this does not seem to be intentional which is why we would like to manually overwrite this in the configuration. dhcpcd only allows setting a maximum MTU of 1472 bytes which does not seem to have any rationale (any more). Although Ethernet might limit any MTU to less, IPv6 and IPv4 support MTUs of up to 64KiB. This patch allows the user to configure the MTU freely with providing some sanity check. Signed-off-by: Michael Tremer --- src/dhcp-common.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/dhcp-common.h b/src/dhcp-common.h index a82fcd4c..d6620822 100644 --- a/src/dhcp-common.h +++ b/src/dhcp-common.h @@ -46,10 +46,11 @@ #define NS_MAXLABEL MAXLABEL #endif -/* Max MTU - defines dhcp option length */ -#define IP_UDP_SIZE 28 -#define MTU_MAX 1500 - IP_UDP_SIZE -#define MTU_MIN 576 + IP_UDP_SIZE +/* Max/Min MTU */ +#define MTU_MAX 65536 +#define MTU_MIN 576 + +#define IP_UDP_SIZE 28 #define OT_REQUEST (1 << 0) #define OT_UINT8 (1 << 1) -- 2.30.2