+ * sys_cleanup - restore any system state we modified before exiting:
+ * mark the interface down, delete default route and/or proxy arp entry.
+ * This should call die() because it's called from die().
+ */
+void
+sys_cleanup()
+{
+ struct ifreq ifr;
+
+ if (if_is_up) {
+ strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+ if (ioctl(sockfd, SIOCGIFFLAGS, &ifr) >= 0
+ && ((ifr.ifr_flags & IFF_UP) != 0)) {
+ ifr.ifr_flags &= ~IFF_UP;
+ ioctl(sockfd, SIOCSIFFLAGS, &ifr);
+ }
+ }
+ if (ifaddrs[0])
+ cifaddr(0, ifaddrs[0], ifaddrs[1]);
+ if (default_route_gateway)
+ cifdefaultroute(0, default_route_gateway);
+ if (proxy_arp_addr)
+ cifproxyarp(0, proxy_arp_addr);
+}
+
+/*
+ * sys_close - Clean up in a child process before execing.
+ */
+void
+sys_close()
+{
+ close(sockfd);
+ if (loop_slave >= 0) {
+ close(loop_slave);
+ close(loop_master);
+ }
+}
+
+/*
+ * sys_check_options - check the options that the user specified