I am in the proces of building an embedded kernel which I wanted to limit in both functionality and memory. For this reason I disabled CONFIG_PROC_SYSCTL. I have figured out the hard way that this functionality implements the successful randomisation of source ports, it might be responsible for the initialisation of net.ipv4.ip_local_port_range. Effectively, booting a kernel with ip=dhcp works. Ping-pong (ICMP) to and from an address works. DNS queries (UDP/53) don't because the source port remains 0, a connection to a typical webserver also seems to result in a no reply situation.
Created attachment 134641 [details] Move local port range init
Stephan, does it work for you ? -- Ueimor
Tested-by: Stefan de Konink <stefan@konink.de> I have just tested the patch. Without /proc/sys present, networking works now. Thanks!