--- /dev/null
+.\" Copyright (c) 1997 by Takamichi Tateoka. All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\" notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\" notice, this list of conditions and the following disclaimer in the
+.\" documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\" must display the following acknowledgement:
+.\" This product includes software developed by Takamichi Tateoka.
+.\" 4. Neither the name of the author may be used to endorse or promote
+.\" products derived from this software without specific prior
+.\" written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY TAKAMICHI TATEOKA ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.Dd November 20, 2014
+.Dt CHOPARP 8
+.Os
+.Sh NAME
+.Nm choparp
+.Nd cheap and omitted proxy ARP
+.Sh SYNOPSIS
+.Nm chpoarp
+.Ar if_name mac_addr
+.Oo Fl Oc Ns Ar net_addr Ns
+.Op / Ns Ar net_mask
+.Ar ...
+.Sh DESCRIPTION
+.Pp
+.Nm choparp
+is a easy-to-use proxy ARP daemon.
+It watches ARP request packets visible on the interface specified by argument
+.Ar if_name ,
+and sends proxy ARP reply to the sender if the ARP request queries the
+MAC address
+.Pq ethernet hardware address
+for the network specified by
+.Ar net_addr Ns / Ar net_mask .
+.Pp
+.Ar mac_addr
+is th MAC address to be published for the specified hosts.
+It is normally the address of
+.Ar if_name .
+The format of
+.Ar mac_addr
+must be 6 colon-separated bytes of hexadecimal value, such as
+.Ad 00:00:01:01:14:46 .
+The keyword
+.Ad auto
+can also be used to use the address of
+.Ar if_name
+from the system configuration.
+.Pp
+A
+.Xr carp 4
+virtual router address can be specified as
+.Ad vhid:<hex>
+.
+.Pp
+.Ar net_addr
+must be in dotted quad notation
+.Pq for example Ad 133.138.1.134
+or be a 32 bit hexadecimal value starting with
+.Dq 0x
+.Pq for example Ad 0x858a0186 .
+.Ar net_mask
+can likewise be speficied as a dotted quad or hexadecimal value,
+or alternatively as a mask length. The following address specifications
+are therefore equivalent:
+.Bl -item -offset indent
+.It
+.Ad 192.168.98.0/255.255.254.0
+.It
+.Ad 192.168.98.0/0xfffffe00
+.It
+.Ad 192.168.98.0/23
+.El
+.Pp
+Multiple addresses can be specified.
+Addresses can be
+.Em excluded
+by preceding them with
+.Fl
+.Sh EXAMPLES
+If you have network interface
+.Dq ne0
+with MAC address
+.Dq 00:00:01:01:14:16 ,
+and would like to send proxy ARP reply for 192.168.0.64/26,
+the argument would be as follows:
+.Bd -literal -offset indent
+choparp ne0 00:00:01:01:14:46 192.168.0.64/255.255.255.192
+.Ed
+.Sh BUGS
+Supports Ethernet interfaces only.
+Handles single interface at a time.
+.Pq you can start multiple Nm choparp No for multiple interfaces, though .
--- /dev/null
+/*
+ choparp - cheap & omitted proxy arp
+
+ Copyright (c) 1997 Takamichi Tateoka (tree@mma.club.uec.ac.jp)
+ Copyright (c) 2002-2015 Thomas Quinot (thomas@cuivre.fr.eu.org)
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions
+ are met:
+ 1. Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+ 3. Neither the name of the authors nor the names of their contributors
+ may be used to endorse or promote products derived from this software
+ without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
+ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ SUCH DAMAGE.
+
+
+ History:
+ 17 Jun 1997 Creation (tate)
+ 7 Oct 1997 fix some comments (tate)
+ 19 Jun 1998 fix read result as ssize_t (tate / pointed by msaitoh)
+
+*/
+
+#define _GNU_SOURCE /* asprintf */
+
+#include <pcap.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <net/if.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netinet/if_ether.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+
+#ifndef __linux__
+#include <ifaddrs.h>
+#include <net/if_dl.h>
+#endif
+
+/* ARP Header */
+#define ARP_REQUEST 1 /* ARP Request */
+#define ARP_REPLY 2 /* ARP Reply */
+
+struct cidr {
+ struct cidr *next;
+ struct in_addr addr; /* addr and mask are host order */
+ struct in_addr mask;
+};
+
+struct cidr *targets = NULL, *excludes = NULL;
+char errbuf[PCAP_ERRBUF_SIZE];
+u_char target_mac[ETHER_ADDR_LEN]; /* target MAC address */
+
+char* cidr_to_str(struct cidr *a) {
+ char buf[64];
+ char *res = NULL;
+ int res_alloc, res_len;
+ int len;
+
+ while (a) {
+ if (a->mask.s_addr == INADDR_NONE) {
+ len = snprintf(buf, sizeof buf, "dst host %s", inet_ntoa(a->addr));
+ } else {
+ len = snprintf(buf, sizeof buf, "dst net %s mask ", inet_ntoa(a->addr));
+ len += snprintf(buf + len, sizeof buf - len, "%s", inet_ntoa(a->mask));
+ }
+
+ if (!res) {
+ res_alloc = 1024;
+ res = malloc(res_alloc);
+ strncpy(res, buf, res_alloc);
+ res_len = len;
+
+ } else {
+ if (res_len + len + 5 > res_alloc) {
+ res_alloc *= 2;
+ res = realloc(res, res_alloc);
+ }
+ strncat(res, " or ", res_alloc - res_len - 1);
+ res_len += 4;
+ strncat(res, buf, res_alloc - res_len - 1);
+ res_len += len;
+ }
+
+ a = a->next;
+ }
+ return res;
+}
+
+pcap_t *
+open_pcap(char *ifname, char *filter_str) {
+ pcap_t *pc = NULL;
+ struct bpf_program filter;
+
+ /* Set up PCAP */
+ if ((pc = pcap_open_live(ifname, 128, 0, 512, errbuf))==NULL){
+ fprintf(stderr, "pcap_open_live failed: %s\n", errbuf);
+ exit(1);
+ }
+
+ /* Compiles the filter expression */
+ if (pcap_compile(pc, &filter, filter_str, 1, PCAP_NETMASK_UNKNOWN) == -1){
+ fprintf(stderr, "pcap_compile failed: %s\n", pcap_geterr(pc) );
+ exit(1);
+ }
+
+ /* Set filter program */
+ if (pcap_setfilter(pc, &filter) == -1){
+ fprintf(stderr, "pcap_setfilter failed: %s\n", pcap_geterr(pc));
+ exit(1);
+ }
+
+ pcap_freecode(&filter);
+ return pc;
+}
+
+void
+gen_arpreply(u_char *buf) {
+ struct ether_arp *arp;
+ struct in_addr ipbuf;
+
+ /* set ethernet dst/src address */
+ memcpy(buf, buf+ETHER_ADDR_LEN, ETHER_ADDR_LEN);
+ memcpy(buf+ETHER_ADDR_LEN, target_mac, ETHER_ADDR_LEN);
+
+ /* set result of ARP request */
+ arp = (struct ether_arp *)(buf + ETHER_HDR_LEN);
+ memcpy((char*) &ipbuf, arp->arp_tpa, sizeof(ipbuf)); /* save protocol addr */
+ memcpy(arp->arp_tha, arp->arp_sha, sizeof(arp->arp_tha)); /* set target hard addr */
+ memcpy(arp->arp_tpa, arp->arp_spa, sizeof(arp->arp_tpa)); /* set target proto addr */
+ memcpy(arp->arp_spa, (char *)&ipbuf, sizeof(ipbuf)); /* set source protocol addr */
+ memcpy(arp->arp_sha, target_mac, ETHER_ADDR_LEN); /* set source hard addr */
+ arp->arp_op = htons(ARPOP_REPLY);
+}
+
+void
+process_arp(u_char *user, const struct pcap_pkthdr *pkthdr, const u_char *packet) {
+ gen_arpreply((u_char *)packet);
+ pcap_inject((pcap_t *)user, packet, pkthdr->len);
+}
+
+int
+setmac(char *addr, char *ifname){
+ u_int m0, m1, m2, m3, m4, m5;
+
+ if (!strcmp (addr, "auto")) {
+#ifdef __linux__
+ int fd;
+ struct ifreq ifr;
+
+ if ((fd = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
+ perror("socket");
+ return -1;
+ }
+
+ strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name);
+
+ if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) {
+ perror("ioctl(SIOCGIFHWADDR)");
+ return -1;
+ }
+ memcpy(target_mac, ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
+ return 0;
+#else
+ struct ifaddrs *ifas, *ifa;
+
+ getifaddrs (&ifas);
+ for (ifa = ifas; ifa != NULL; ifa = ifa->ifa_next) {
+#define SDL ((struct sockaddr_dl *)ifa->ifa_addr)
+ if (strcmp (ifa->ifa_name, ifname)
+ || SDL->sdl_family != AF_LINK
+ || SDL->sdl_alen != ETHER_ADDR_LEN)
+ continue;
+ memcpy (target_mac, SDL->sdl_data + SDL->sdl_nlen, ETHER_ADDR_LEN);
+ return 0;
+ }
+#endif
+ fprintf(stderr, "%s: not found\n", ifname);
+ return -1;
+
+ } else if (!strncmp (addr, "vhid:", 4)) {
+ /*
+ * Virtual router mac address
+ * CARP address format: 00:00:5e:00:01:<VHID>
+ */
+ char *vhid = addr + 5;
+ if (!*vhid)
+ return(-1);
+ m0 = 0;
+ m1 = 0;
+ m2 = 0x5e;
+ m3 = 0;
+ m4 = 1;
+ m5 = atoi(vhid);
+ } else if (sscanf(addr, "%x:%x:%x:%x:%x:%x", &m0, &m1, &m2, &m3, &m4, &m5) < 6) {
+ fprintf(stderr, "invalid MAC address: %s", addr);
+ return(-1);
+ }
+ target_mac[0] = (u_char )m0;
+ target_mac[1] = (u_char )m1;
+ target_mac[2] = (u_char )m2;
+ target_mac[3] = (u_char )m3;
+ target_mac[4] = (u_char )m4;
+ target_mac[5] = (u_char )m5;
+ return(0);
+}
+
+int
+atoip(char *buf, u_int32_t *ip_addr){
+ u_int i0, i1, i2, i3;
+
+ if (sscanf(buf, "%u.%u.%u.%u", &i0, &i1, &i2, &i3) == 4){
+ *ip_addr = (i0 << 24) + (i1 << 16) + (i2 << 8) + i3;
+ return(0);
+ }
+ if (sscanf(buf, "0x%lx", (unsigned long *) ip_addr) == 1)
+ return(0);
+
+ return(-1);
+}
+
+void
+usage(void){
+ fprintf(stderr,"usage: choparp if_name mac_addr [-]addr/mask...\n");
+ exit(-1);
+}
+
+int
+main(int argc, char **argv){
+ pcap_t *pc;
+ char *ifname;
+ char *filter, *targets_filter, *excludes_filter;
+ struct cidr **targets_tail = &targets, **excludes_tail = &excludes;
+#define APPEND(LIST,ADDR,MASK) \
+ do { \
+ *(LIST ## _tail) = malloc(sizeof (struct cidr)); \
+ (*(LIST ## _tail))->addr.s_addr = htonl(ADDR); \
+ (*(LIST ## _tail))->mask.s_addr = htonl(MASK); \
+ (*(LIST ## _tail))->next = NULL; \
+ (LIST ## _tail) = &(*(LIST ## _tail))->next; \
+ } while (0)
+
+ if (argc < 4)
+ usage();
+
+ ifname = argv[1];
+ if (setmac(argv[2], ifname)) {
+ exit(1);
+ }
+ argv += 3; argc -= 3;
+
+ while (argc > 0) {
+ u_int32_t addr, mask = ~0;
+ char *slash = strchr (*argv, '/');
+ int exclude = 0;
+
+ if (**argv == '-') {
+ (*argv)++;
+ exclude = 1;
+ }
+ if (slash != NULL)
+ *(slash++) = '\0';
+ if (atoip (*argv, &addr))
+ usage();
+ if (slash != NULL) {
+ char *end;
+ u_int32_t len = strtol (slash, &end, 10);
+ if (*end == '\0')
+ mask <<= (32 - len);
+ else if (atoip (slash, &mask))
+ usage();
+ }
+ if (exclude)
+ APPEND(excludes, addr, mask);
+ else
+ APPEND(targets, addr, mask);
+
+ argv++, argc--;
+ }
+
+#ifdef DEBUG
+#define SHOW(LIST) \
+ do { \
+ struct cidr *t; \
+ fprintf (stderr, #LIST ":\n"); \
+ for (t = LIST; t; t = t->next) { \
+ fprintf (stderr, " %s", inet_ntoa (t->addr)); \
+ fprintf (stderr, "/%s\n", inet_ntoa (t->mask)); \
+ } \
+ } while (0)
+
+ SHOW(targets);
+ SHOW(excludes);
+ exit (0);
+#endif
+
+ targets_filter = cidr_to_str(targets);
+ excludes_filter = cidr_to_str(excludes);
+
+#define TMPL_FILTER "arp[2:2] == 0x0800 " /* Protocol: IPv4 */ \
+ "and arp[4] == 6 " /* Hw addr length: 6 */ \
+ "and arp[5] == 4 " /* Proto addr length: 4 */ \
+ "and arp[6:2] == 1 " /* Operation: Request */ \
+ "and (%s)"
+
+#define EXCL_FILTER TMPL_FILTER " and not (%s)"
+ if (excludes_filter == NULL)
+ asprintf (&filter, TMPL_FILTER, targets_filter);
+ else
+ asprintf (&filter, EXCL_FILTER, targets_filter, excludes_filter);
+
+#ifdef DEBUG
+ fprintf(stderr, "Filter on %s: %s\n", ifname, filter);
+#endif
+ if ((pc = open_pcap(ifname, filter)) < 0)
+ exit(1);
+ free(filter);
+ pcap_loop(pc, 0, process_arp, (u_char*)pc);
+ exit(1);
+}
--- /dev/null
+Summary: proxy ARP daemon
+Name: choparp
+Version: 0
+#Rel: YYMM.#
+Release: 1503.1
+License: BSD
+Group: Applications/Networking
+Source0: choparp.c
+Source1: README.md
+Source2: choparp.8
+Source3: sample.conf
+Source4: choparp.sysconfig
+Source5: choparp-service-generator
+Source6: choparp.target
+Source7: choparp@.service
+URL: https://github.com/quinot/choparp
+BuildRequires: libpcap-devel
+BuildRoot: %{tmpdir}/%{name}-%{version}-root-%(id -u -n)
+
+%description
+choparp is a proxy ARP daemon. It listens for ARP requests on a
+network interface, and sends ARP replies with a specified MAC
+addresses when the requested IP addresses matches a user-provided
+list.
+
+%prep
+%setup -qcT
+install %{SOURCE0} .
+install %{SOURCE1} .
+
+%build
+gcc -o choparp choparp.c -lpcap
+
+%install
+rm -rf $RPM_BUILD_ROOT
+install -d $RPM_BUILD_ROOT{%{_sbindir},%{_mandir}/man8/} \
+ $RPM_BUILD_ROOT%{_docdir}/%{name}-%{version} \
+ $RPM_BUILD_ROOT/etc/{sysconfig,%{name}} \
+ $RPM_BUILD_ROOT{%{systemdtmpfilesdir},%{systemdunitdir}} \
+ $RPM_BUILD_ROOT/lib/systemd/system-generators
+
+install choparp $RPM_BUILD_ROOT%{_sbindir}
+
+install %{SOURCE2} $RPM_BUILD_ROOT%{_mandir}/man8/
+
+install %{SOURCE3} $RPM_BUILD_ROOT%{_sysconfdir}/%{name}/eth0.conf
+install %{SOURCE4} $RPM_BUILD_ROOT/etc/sysconfig/%{name}
+
+install -p %{SOURCE5} $RPM_BUILD_ROOT/lib/systemd/system-generators/%{name}-service-generator
+install -p %{SOURCE6} $RPM_BUILD_ROOT%{systemdunitdir}/%{name}.target
+install -p %{SOURCE7} $RPM_BUILD_ROOT%{systemdunitdir}/%{name}@.service
+
+
+%clean
+rm -rf $RPM_BUILD_ROOT
+
+%post
+%service %{name} restart
+%systemd_post %{name}.target
+
+%preun
+if [ "$1" = "0" ]; then
+ %service %{name} stop
+fi
+%systemd_preun %{name}.target
+
+%postun
+%systemd_reload
+
+%files
+%defattr(644,root,root,755)
+%doc README.md
+%attr(755,root,root) %{_sbindir}/*
+%config(noreplace) %verify(not md5 mtime size) /etc/sysconfig/%{name}
+%attr(755,root,root) /lib/systemd/system-generators/%{name}-service-generator
+%{systemdunitdir}/%{name}.target
+%{systemdunitdir}/%{name}@.service
+%attr(770,root,root) %dir %{_sysconfdir}/%{name}
+%config(noreplace) %verify(not md5 mtime size) %{_sysconfdir}/%{name}/eth0.conf
+%{_mandir}/man8/*
+
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