From 5f251e1f281de806241540174f32ff5a183f064f Mon Sep 17 00:00:00 2001 From: Mark Qvist Date: Thu, 28 May 2020 14:45:07 +0200 Subject: [PATCH] Raspbian MTU setting description in readme --- README.md | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/README.md b/README.md index 813861c..ff6fd12 100644 --- a/README.md +++ b/README.md @@ -111,12 +111,13 @@ tnc0: flags=4305 mtu 400 TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 ``` -## Known Issues +## Worth Knowing on Raspbian -The utility fails to set the interface MTU on some Raspbian versions. After attaching the TNC, check that the correct MTU has been set on the interface with ifconfig or similar. If not, you can set it manually with a command like: +On some versions of Raspbian (and probably other operating systems), the DHCP client daemon _dhcpcd_ interferes with TNC interfaces, by overriding their MTU and trying to auto-configure link-local addresses. You probably don't want this, and it can be disabled by editing the __/etc/dhcpcd.conf__ file, adding a statement telling _dhcpcd_ to ignore your TNC interface: -```sh -# Attach interface -ifconfig tnc0 mtu 478 +``` +# Add the following statement somewhere at the beginning +# of /etc/dhcpcd.conf to prevent dhcpcd from changing MTU +denyinterfaces tnc0 ``` \ No newline at end of file