Make OpenWRT work, save nonce in addteam

doc/openwrt/README

@@ -20,7 +20,13 @@ Instructions for setting up OpenWRT
 After installing OpenWRT:
 
 * Change the root password
-* Install the kmod-ipv6, radvd, and luci-app-radvd packages
+* Install the following packages:
+    ip6tables
+    kmod-ip6tables
+    kmod-ipv6
+    libip6tc
+    luci-app-radvd
+    radvd
 * Configure the LAN interface as 10.0.0.1/16 and
   fd84:b410:3441::1/64
 * Tell DHCP to begin at 257 after the base IP: this will assure
@@ -28,7 +34,7 @@ After installing OpenWRT:
 * Disable router solicitations on LAN
 * Enable WPA2, with the password "correct horse battery staple"
 * Turn on router advertisements (under radvd) on LAN
-* Enable prefix fd84:b410:3441::1/54 under radvd
+* Enable prefix fd84:b410:3441::1/64 under radvd
 
 This should be sufficient to bring up the router for running the
 contest.  If you want to get fancy, you can scp the files in

packages/mcp/bin/addteam

@@ -20,6 +20,9 @@ www=${CTF_BASE:-/var/www}
 mkdir -p $base/teams/names
 mkdir -p $base/teams/colors
 
+[ -f $base/teams/nonce ] || dd if=/dev/urandom count=1 | md5sum | cut -b 1-8 > $base/teams/nonce
+nonce=$(cat $base/teams/nonce)
+
 # Assign a color.  I spent weeks selecting a color pallette that
 # wouldn't be hell on people with protanopia.  Please don't change these
 # colors.
@@ -45,7 +48,7 @@ esac
 # Compute hash of team name; they'll use this for everything in the
 # contest instead of their team name, which makes stuff much easier on
 # me since all team hashes are in the set /[0-9a-f]{8}/.
-hash=$(dd if=/dev/urandom count=1 2>/dev/null | md5sum | cut -b 1-8)
+hash=$(printf "%s:%s" $nonce "$1" | md5sum | cut -b 1-8)
 
 echo "$1" > $base/teams/names/$hash
 echo "$color" > $base/teams/colors/$hash