--- v2.4.5/linux/include/linux/inetdevice.h~ Sat Jun 2 08:59:33 2001 +++ linux/include/linux/inetdevice.h Sat Jun 2 09:02:13 2001 @@ -17,6 +17,7 @@ int forwarding; int mc_forwarding; int tag; + int hidden; int arp_filter; void *sysctl; }; @@ -44,6 +45,7 @@ #define IN_DEV_LOG_MARTIANS(in_dev) (ipv4_devconf.log_martians || (in_dev)->cnf.log_martians) #define IN_DEV_PROXY_ARP(in_dev) (ipv4_devconf.proxy_arp || (in_dev)->cnf.proxy_arp) +#define IN_DEV_HIDDEN(in_dev) ((in_dev)->cnf.hidden && ipv4_devconf.hidden) #define IN_DEV_SHARED_MEDIA(in_dev) (ipv4_devconf.shared_media || (in_dev)->cnf.shared_media) #define IN_DEV_TX_REDIRECTS(in_dev) (ipv4_devconf.send_redirects || (in_dev)->cnf.send_redirects) #define IN_DEV_SEC_REDIRECTS(in_dev) (ipv4_devconf.secure_redirects || (in_dev)->cnf.secure_redirects) --- v2.4.5/linux/include/linux/sysctl.h~ Sat Jun 2 08:59:38 2001 +++ linux/include/linux/sysctl.h Sat Jun 2 09:04:12 2001 @@ -325,7 +325,8 @@ NET_IPV4_CONF_BOOTP_RELAY=10, NET_IPV4_CONF_LOG_MARTIANS=11, NET_IPV4_CONF_TAG=12, - NET_IPV4_CONF_ARPFILTER=13 + NET_IPV4_CONF_ARPFILTER=13, + NET_IPV4_CONF_HIDDEN=14, }; /* /proc/sys/net/ipv6 */ --- v2.4.5/linux/net/ipv4/arp.c~ Sat Jun 2 08:59:38 2001 +++ linux/net/ipv4/arp.c Sat Jun 2 09:15:50 2001 @@ -66,6 +66,8 @@ * Alexey Kuznetsov: new arp state machine; * now it is in net/core/neighbour.c. * Krzysztof Halasa: Added Frame Relay ARP support. + * Julian Anastasov: "hidden" flag: hide the + * interface and don't reply for it */ #include @@ -742,9 +755,22 @@ /* Special case: IPv4 duplicate address detection packet (RFC2131) */ if (sip == 0) { - if (arp->ar_op == __constant_htons(ARPOP_REQUEST) && - inet_addr_type(tip) == RTN_LOCAL) + int reply; + struct net_device *dev2 = NULL; + struct in_device *in_dev2 = NULL; + + reply = + (arp->ar_op == __constant_htons(ARPOP_REQUEST) && + (dev2 = ip_dev_find(tip)) != NULL && + (dev2 == dev || + ((in_dev2 = in_dev_get(dev2)) != NULL && + !IN_DEV_HIDDEN(in_dev2)))); + if (dev2) { + if (in_dev2) in_dev_put(in_dev2); + dev_put(dev2); + if (reply) arp_send(ARPOP_REPLY,ETH_P_ARP,tip,dev,tip,sha,dev->dev_addr,dev->dev_addr); + } goto out; } @@ -758,6 +784,21 @@ n = neigh_event_ns(&arp_tbl, sha, &sip, dev); if (n) { int dont_send = 0; + if (ipv4_devconf.hidden && + skb->pkt_type != PACKET_HOST) { + struct net_device *dev2 = NULL; + struct in_device *in_dev2 = NULL; + + dont_send |= + ((dev2 = ip_dev_find(tip)) != NULL && + dev2 != dev && + (in_dev2=in_dev_get(dev2)) != NULL && + IN_DEV_HIDDEN(in_dev2)); + if (dev2) { + if (in_dev2) in_dev_put(in_dev2); + dev_put(dev2); + } + } if (IN_DEV_ARPFILTER(in_dev)) dont_send |= arp_filter(sip,tip,dev); if (!dont_send) --- v2.4.5/linux/net/ipv4/devinet.c~ Sat Jun 2 08:59:38 2001 +++ linux/net/ipv4/devinet.c Sat Jun 2 09:17:26 2001 @@ -736,7 +736,8 @@ read_lock(&in_dev->lock); for_primary_ifa(in_dev) { - if (ifa->ifa_scope != RT_SCOPE_LINK && + if (!IN_DEV_HIDDEN(in_dev) && + ifa->ifa_scope != RT_SCOPE_LINK && ifa->ifa_scope <= scope) { read_unlock(&in_dev->lock); read_unlock(&inetdev_lock); @@ -1016,7 +1017,7 @@ static struct devinet_sysctl_table { struct ctl_table_header *sysctl_header; - ctl_table devinet_vars[14]; + ctl_table devinet_vars[15]; ctl_table devinet_dev[2]; ctl_table devinet_conf_dir[2]; ctl_table devinet_proto_dir[2]; @@ -1058,6 +1059,9 @@ &proc_dointvec}, {NET_IPV4_CONF_TAG, "tag", &ipv4_devconf.tag, sizeof(int), 0644, NULL, + &proc_dointvec}, + {NET_IPV4_CONF_HIDDEN, "hidden", + &ipv4_devconf.hidden, sizeof(int), 0644, NULL, &proc_dointvec}, {NET_IPV4_CONF_ARPFILTER, "arp_filter", &ipv4_devconf.arp_filter, sizeof(int), 0644, NULL, --- v2.4.5/linux/Documentation/filesystems/proc.txt~ Sat Jun 2 08:58:39 2001 +++ linux/Documentation/filesystems/proc.txt Sat Jun 2 09:01:06 2001 @@ -1578,6 +1578,16 @@ Determines whether to send ICMP redirects to other hosts. +hidden +------ + +Hide addresses attached to this device from another devices. +Such addresses will never be selected by source address autoselection +mechanism, host does not answer broadcast ARP requests for them, +does not announce it as source address of ARP requests, but they +are still reachable via IP. This flag is activated only if it is +enabled both in specific device section and in "all" section. + Routing settings ---------------- --- v2.4.5/linux/Documentation/networking/ip-sysctl.txt~ Sat Jun 2 08:59:19 2001 +++ linux/Documentation/networking/ip-sysctl.txt Sat Jun 2 09:01:06 2001 @@ -392,6 +392,14 @@ Default value is 0. Note that some distributions enable it in startip scripts. +hidden - BOOLEAN + Hide addresses attached to this device from another devices. + Such addresses will never be selected by source address autoselection + mechanism, host does not answer broadcast ARP requests for them, + does not announce it as source address of ARP requests, but they + are still reachable via IP. This flag is activated only if it is + enabled both in specific device section and in "all" section. + Alexey Kuznetsov. kuznet@ms2.inr.ac.ru