Cannot edit hosts file. Please help

I need to use a hosts file because the Cisco AnyConnect VPN client won't allow me to resolve internal DNS names.

When I do a

sudo vi /private/etc/hosts

I get an "empty" hosts file. I try to edit anyway, but when I try to save I get

E166: Can't Open Linked File For Editing

wtf? Linked where?

any advice would be welcome.

 

I have already gone through dozens of pages of documentation -nothing has worked

If I do a ls -la in the /etc/ directory, I see

lrwxr-xr-x 1 root wheel 18 Jan 13 2010 hosts -> /etc/gasmask/hosts

there is some kind of link

but /etc/gasmask doesn't exist or cannot be accessed