I didn't see this "fix" anywhere on OESF, so I decided to post it here.
This has worked for me on my SL-C3100. I'm not sure if this works on all covered models.
------------------------------------------------
credit goes to Stefani at omegamoon blog:
dhclient will fail with message "can't create addrlist socket" due the bad or missing support of the kernel capabilities.

Setting the user and group id of dhcp both to 0 (root) will solve the problem.

------------------------------------------------
credit goes to crash at omegamoon blog:
You have to modify the "dhcp" entry in the /etc/passwd file. That was a tip by Stefani earlier before:
"...Setting the user and group id of dhcp both to 0 (root) will solve the problem..."

ah, that explains it! of course, if dhcpcd/dhclient wasn't running as root, it'd b0rk!

thanks for alerting us. that really does help!

To those here who are linux newbies (like me!), would that be:

Assuming I was already in /etc/passwd ?

Wait, further research makes me think this is a modification to the actual /etc/passwd file?

And in fact it is. For newbies: modify the dhcp line in /etc/passwd. The numbers 101 and 103 should be 0's.