The interface is set to the configured state even if configuration has been failed # ifup eth1 Internet Systems Consortium DHCP Client 4.4.2 Copyright 2004-2020 Internet Systems Consortium. All rights reserved. For info, please visit https://www.isc.org/software/dhcp/ [ 506.720497] e1000: eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX [ 506.754841] IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready Listening on LPF/eth1/52:54:00:12:34:56 Sending on LPF/eth1/52:54:00:12:34:56 Sending on Socket/fallback Created duid "\000\001\000\001&\020\210BRT\000\0224V". DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 3 DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 7 DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 8 DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 15 DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 11 DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 17 No DHCPOFFERS received. No working leases in persistent database - sleeping. # ifup eth1 ifup: interface eth1 already configured #
And Test on another host which also installed with BusyBox v1.31.1 # ifconfig eth1 eth1 Link encap:Ethernet HWaddr 00:1E:67:65:8D:9D BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:2551 errors:0 dropped:0 overruns:0 frame:0 TX packets:3983 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:617252 (602.7 KiB) TX bytes:1347016 (1.2 MiB) Memory:d0940000-d095ffff # ifup -v eth1 run-parts /etc/network/if-pre-up.d run-parts: /etc/network/if-pre-up.d: No such file or directory ip link set eth1 up udhcpc -R -b -p /var/run/udhcpc.eth1.pid -i eth1 udhcpc: started, v1.31.1 udhcpc: sending discover udhcpc: sending discover udhcpc: sending discover udhcpc: no lease, forking to background run-parts /etc/network/if-up.d run-parts: /etc/network/if-up.d: No such file or directory # ifconfig eth1 eth1 Link encap:Ethernet HWaddr 00:1E:67:65:8D:9D inet6 addr: fe80::21e:67ff:fe65:8d9d/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:2554 errors:0 dropped:0 overruns:0 frame:0 TX packets:3997 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:618248 (603.7 KiB) TX bytes:1348510 (1.2 MiB) Memory:d0940000-d095ffff # ifup -v eth1 ifup: interface eth1 already configured
Maybe it is not issue as it indicate "udhcpc: no lease, forking to background" in the first run, so it makes sense get "ifup: interface eth1 already configured" if rerun "ifup eth1".