diff --git a/doc/bird.sgml b/doc/bird.sgml
index 087a4eb..16de68e 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -317,7 +317,7 @@ protocol rip {
 	Besides, there are some predefined numeric constants based on /etc/iproute2/rt_* files.
 	A list of defined constants can be seen (together with other symbols) using 'show symbols' command.
 
-	<tag>router id <m/IPv4 address/</tag> Set BIRD's router ID. It's a world-wide unique identification of your router, usually one of router's IPv4 addresses. Default: in IPv4 version, the lowest IP address of a non-loopback interface. In IPv6 version, this option is mandatory. 
+	<tag>router id <m/IPv4 address|"interface"/</tag> Set BIRD's router ID. It's a world-wide unique identification of your router, usually one of router's IPv4 addresses. Default: in IPv4 version, the lowest IP address of a non-loopback interface. In IPv6 version, this option is mandatory. 
 
 	<tag>listen bgp [address <m/address/] [port <m/port/] [dual]</tag>
 	This option allows to specify address and port where BGP
@@ -421,7 +421,7 @@ to zero to disable it. An empty <cf><m/switch/</cf> is equivalent to <cf/on/
 	state changes and <cf/messages/ logs received BGP messages.
 	Other protocols does not support MRTdump yet.
 
-	<tag>router id <m/IPv4 address/</tag> This option can be used
+	<tag>router id <m/IPv4 address|"interface"/</tag> This option can be used
 	to override global router id for a given protocol. Default:
 	uses global router id.
 
diff --git a/nest/config.Y b/nest/config.Y
index a75dd0c..1cb3e27 100644
--- a/nest/config.Y
+++ b/nest/config.Y
@@ -90,6 +90,10 @@ idval:
      cf_error("Router IDs must be entered as hexadecimal numbers or IPv4 addresses in IPv6 version");
 #endif
    }
+ | TEXT {
+    if (($$ = sysio_get_rtrid($1)) == 0)
+      cf_error("Unable to get primary IPv4 address for interface %s", $1);
+ }
  ;
 
 
diff --git a/sysdep/unix/io.c b/sysdep/unix/io.c
index f91b527..1f73c4a 100644
--- a/sysdep/unix/io.c
+++ b/sysdep/unix/io.c
@@ -17,11 +17,13 @@
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <sys/ioctl.h>
 #include <sys/fcntl.h>
 #include <sys/uio.h>
 #include <sys/un.h>
 #include <unistd.h>
 #include <errno.h>
+#include <net/if.h>
 #include <netinet/in.h>
 #include <netinet/icmp6.h>
 
@@ -669,6 +671,35 @@ get_sockaddr(struct sockaddr_in *sa, ip_addr *a, struct iface **ifa, unsigned *p
 
 #endif
 
+/**
+ * sysio_get_rtrid - get main IPv4 interface address as router id
+ * @iface - interface name
+ * Returns router id or 0 in case of error
+ */
+u32
+sysio_get_rtrid(char *iface)
+{
+  int s;
+  struct ifreq ifr;
+  struct sockaddr_in *sin;
+
+  memset(&ifr, 0, sizeof(struct ifreq));
+  strncpy(ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);
+
+  if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
+    return 0;
+  }
+
+  if (ioctl(s, SIOCGIFADDR, &ifr) != 0) {
+    return 0;
+  }
+
+  close(s);
+
+  sin = (struct sockaddr_in *)&ifr.ifr_addr;
+  return ntohl(sin->sin_addr.s_addr);
+}
+
 
 #ifdef IPV6
 
diff --git a/sysdep/unix/unix.h b/sysdep/unix/unix.h
index 3e85c85..4c9990f 100644
--- a/sysdep/unix/unix.h
+++ b/sysdep/unix/unix.h
@@ -28,6 +28,7 @@ volatile int async_config_flag;
 volatile int async_dump_flag;
 volatile int async_shutdown_flag;
 
+u32 sysio_get_rtrid(char *iface);
 #ifdef IPV6
 #define BIRD_PF PF_INET6
 #define BIRD_AF AF_INET6