projects / people / mfischer / ipfire-2.x.git / blame
| Commit | Line | Data |
|---|---|---|
| 7cdd5505 MT |
1 | From 1acff721a3874a74efc9921a1e07bd48bd7efab0 Mon Sep 17 00:00:00 2001 |
| 2 | From: Michael Tremer <michael.tremer@ipfire.org> | |
| 3 | Date: Tue, 22 Feb 2022 12:07:15 +0000 | |
| 4 | Subject: [PATCH] Allow free selection of MTU by the user | |
| 5 | ||
| 6 | Various ISPs (or equipment?) seem to hand out an MTU of only 576 bytes. | |
| 7 | Hwoever, this does not seem to be intentional which is why we would like | |
| 8 | to manually overwrite this in the configuration. | |
| 9 | ||
| 10 | dhcpcd only allows setting a maximum MTU of 1472 bytes which does not | |
| 11 | seem to have any rationale (any more). Although Ethernet might limit any | |
| 12 | MTU to less, IPv6 and IPv4 support MTUs of up to 64KiB. | |
| 13 | ||
| 14 | This patch allows the user to configure the MTU freely with providing | |
| 15 | some sanity check. | |
| 16 | ||
| 17 | Signed-off-by: Michael Tremer <michael.tremer@ipfire.org> | |
| 18 | --- | |
| 19 | src/dhcp-common.h | 9 +++++---- | |
| 20 | 1 file changed, 5 insertions(+), 4 deletions(-) | |
| 21 | ||
| 22 | diff --git a/src/dhcp-common.h b/src/dhcp-common.h | |
| 23 | index a82fcd4c..d6620822 100644 | |
| 24 | --- a/src/dhcp-common.h | |
| 25 | +++ b/src/dhcp-common.h | |
| 26 | @@ -46,10 +46,11 @@ | |
| 27 | #define NS_MAXLABEL MAXLABEL | |
| 28 | #endif | |
| 29 | ||
| 30 | -/* Max MTU - defines dhcp option length */ | |
| 31 | -#define IP_UDP_SIZE 28 | |
| 32 | -#define MTU_MAX 1500 - IP_UDP_SIZE | |
| 33 | -#define MTU_MIN 576 + IP_UDP_SIZE | |
| 34 | +/* Max/Min MTU */ | |
| 35 | +#define MTU_MAX 65536 | |
| 36 | +#define MTU_MIN 576 | |
| 37 | + | |
| 38 | +#define IP_UDP_SIZE 28 | |
| 39 | ||
| 40 | #define OT_REQUEST (1 << 0) | |
| 41 | #define OT_UINT8 (1 << 1) | |
| 42 | -- | |
| 43 | 2.30.2 | |
| 44 |