Linux client script

diff --git a/client/scripts/linux b/client/scripts/linux
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+++ b/client/scripts/linux
@@ -0,0 +1,156 @@
+#!/bin/sh
+# dhclient-script for Linux. Dan Halbert, March, 1997.
+# No guarantees about this. I'm a novice at the details of Linux
+# networking.
+
+# Notes:
+
+# 0. This script is based on the netbsd script supplied with dhcp-970306.
+
+# 1. ifconfig down apparently deletes all relevant routes and flushes
+# the arp cache, so this doesn't need to be done explicitly.
+
+# 2. The alias address handling here has not been tested AT ALL.
+# I'm just going by the doc of modern Linux ip aliasing, which uses
+# notations like eth0:0, eth0:1, for each alias.
+
+# 3. I have to calculate the network address, and calculate the broadcast
+# address if it is not supplied. This might be much more easily done
+# by the dhclient C code, and passed on.
+
+# 4. TIMEOUT not tested. ping has a flag I don't know, and I'm suspicious
+# of the $1 in its args.
+
+############################################################################
+# This horror, which depends on bash, does a bitwise and of the ip
+# address and the network mask to produce the network address.
+eval `echo $new_ip_address $new_subnet_mask | sed -e 's/\([0-9]\+\).\([0-9]\+\).\([0-9]\+\).\([0-9]\+\) \([0-9]\+\).\([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/new_network_address="$[\1\&\5].$[\2\&\6].$[\3\&\7].$[4\&\8]"/'`
+
+# A similar horror to calculate the broadcast address if it's not given.
+if [ x$new_broadcast_address = x ]; then
+  eval `echo $new_ip_address $new_subnet_mask | sed -e 's/\([0-9]\+\).\([0-9]\+\).\([0-9]\+\).\([0-9]\+\) \([0-9]\+\).\([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/new_broadcast_address="$[(\1\|~\5)\&255].$[(\2\|~\6)\&255].$[(\3\|~\7)\&255].$[(4\|~\8)\&255]"/'`
+fi
+
+if [ x$new_broadcast_address != x ]; then
+  new_broadcast_arg="broadcast $new_broadcast_address"
+fi
+if [ x$old_broadcast_address != x ]; then
+  old_broadcast_arg="broadcast $old_broadcast_address"
+fi
+if [ x$new_subnet_mask != x ]; then
+  new_subnet_arg="netmask $new_subnet_mask"
+fi
+if [ x$old_subnet_mask != x ]; then
+  old_subnet_arg="netmask $old_subnet_mask"
+fi
+if [ x$alias_subnet_mask != x ]; then
+  alias_subnet_arg="netmask $alias_subnet_mask"
+fi
+
+if [ x$reason = xMEDIUM ]; then
+  # Linux doesn't do mediums (ok, ok, media).
+  exit 0
+fi
+
+if [ x$reason = xPREINIT ]; then
+  if [ x$alias_ip_address != x ]; then
+    # Bring down alias interface. Its routes will disappear too.
+    ifconfig $interface:0- inet 0
+  fi
+  ifconfig $interface inet 0.0.0.0 netmask 0.0.0.0 \
+               broadcast 255.255.255.255 up
+  # Add route to make broadcast work. Do not omit netmask.
+  route add default dev $interface netmask 0.0.0.0
+  exit 0
+fi
+
+if [ x$reason = xARPCHECK ] || [ x$reason = xARPSEND ]; then
+  exit 0;
+fi
+  
+if [ x$reason = xBOUND ] || [ x$reason = xRENEW ] || \
+   [ x$reason = xREBIND ] || [ x$reason = xREBOOT ]; then
+  if [ x$old_ip_address != x ] && [ x$alias_ip_address != x ] && \
+               [ x$alias_ip_address != x$old_ip_address ]; then
+    # Possible new alias. Remove old alias.
+    ifconfig $interface:0- inet 0
+  fi
+  if [ x$old_ip_address != x ] && [ x$old_ip_address != x$new_ip_address ]; then
+    # IP address changed. Bringing down the interface will delete all routes,
+    # and clear the ARP cache.
+    ifconfig $interface inet down
+
+  fi
+  if [ x$old_ip_address = x ] || [ x$old_ip_address != x$new_ip_address ] || \
+     [ x$reason = xBOUND ] || [ x$reason = xREBOOT ]; then
+
+    ifconfig $interface inet $new_ip_address $new_subnet_arg \
+                                       $new_broadcast_arg
+    # Add a network route to the computed network address.
+    route add -net $new_network_address $new_subnet_arg dev $interface
+    for router in $new_routers; do
+      route add default gw $router
+    done
+  fi
+  if [ x$new_ip_address != x$alias_ip_address ] && [ x$alias_ip_address != x ];
+   then
+    ifconfig $interface:0- inet 0
+    ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
+    route add -host $alias_ip_address $interface:0
+  fi
+  echo domain $new_domain_name >/etc/resolv.conf
+  for nameserver in $new_domain_name_servers; do
+    echo nameserver $nameserver >>/etc/resolv.conf
+  done
+  exit 0
+fi
+
+if [ x$reason = xEXPIRE ] || [ x$reason = xFAIL ]; then
+  if [ x$alias_ip_address != x ]; then
+    # Turn off alias interface.
+    ifconfig $interface:0- inet 0
+  fi
+  if [ x$old_ip_address != x ]; then
+    # Shut down interface, which will delete routes and clear arp cache.
+    ifconfig $interface inet down
+  fi
+  if [ x$alias_ip_address != x ]; then
+    ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
+    route add -host $alias_ip_address $interface:0
+  fi
+  exit 0
+fi
+
+if [ x$reason = xTIMEOUT ]; then
+  if [ x$alias_ip_address != x ]; then
+    ifconfig $interface:0- inet 0
+  fi
+  ifconfig $interface inet $new_ip_address $new_subnet_arg \
+                                       $new_broadcast_arg
+  set $new_routers
+  ############## what is -w in ping?
+  if ping -q -c 1 -w 1 $1; then
+    if [ x$new_ip_address != x$alias_ip_address ] && \
+                       [ x$alias_ip_address != x ]; then
+      ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
+      route add -host $alias_ip_address dev $interface:0
+    fi
+    route add -net $new_network_address
+    for router in $new_routers; do
+      route add default gw $router
+    done
+    echo domain $new_domain_name >/etc/resolv.conf.std
+    for nameserver in $new_domain_name_servers; do
+      echo nameserver $nameserver >>/etc/resolv.conf.std
+    done
+    if [ -f /etc/resolv.conf ]; then
+      rm -f /etc/resolv.conf
+      ln /etc/resolv.conf.std /etc/resolv.conf
+    fi
+    exit 0
+  fi
+  ifconfig $interface inet down
+  exit 1
+fi
+
+exit 0