diff --git a/ip6.h b/ip6.h
index 4e7680e..c71615c 100644
--- a/ip6.h
+++ b/ip6.h
@@ -2,9 +2,15 @@
 #define IP6_H
 
 #include "byte.h"
+#include "uint32.h"
 
-unsigned int scan_ip6(const char *src,char *ip);
-unsigned int fmt_ip6(char *dest,const char *ip);
+unsigned int scan_ip6(const char* src,char* ip);
+unsigned int fmt_ip6(char* dest,const char* ip);
+unsigned int fmt_ip6c(char* dest,const char* ip);
+
+unsigned int scan_ip6if(const char* src,char* ip,uint32* scope_id);
+unsigned int fmt_ip6if(char* dest,const char* ip,uint32 scope_id);
+unsigned int fmt_ip6ifc(char* dest,const char* ip,uint32 scope_id);
 
 unsigned int scan_ip6_flat(const char *src,char *);
 unsigned int fmt_ip6_flat(char *dest,const char *);
diff --git a/socket/fmt_ip6.3 b/socket/fmt_ip6.3
index d38a768..7a1e840 100644
--- a/socket/fmt_ip6.3
+++ b/socket/fmt_ip6.3
@@ -29,4 +29,4 @@ contain every possible fmt_ip6 output plus \\0.
   char ip[16];
   buf[fmt_ip6(buf,ip)]=0;
 .SH "SEE ALSO"
-scan_ip6(3), fmt_ip4(3)
+fmt_ip6c(3), fmt_ip6if(3), scan_ip6(3), fmt_ip4(3)
diff --git a/socket/fmt_ip6c.3 b/socket/fmt_ip6c.3
new file mode 100644
index 0000000..607a57d
--- /dev/null
+++ b/socket/fmt_ip6c.3
@@ -0,0 +1,32 @@
+.TH fmt_ip6c 3
+.SH NAME
+fmt_ip6c \- write a formatted ASCII representation of an IPv6 number
+.SH SYNTAX
+.B #include <ip6.h>
+
+unsigned int \fBfmt_ip6c\fP(char *\fIdest\fR,const char \fIip\fR[16]);
+.SH DESCRIPTION
+fmt_ip6c formats an IPv6 number in ASCII representation from \fIip\fR and
+writes the result into \fIdest\fR. It returns the number of bytes
+written.
+
+fmt_ip6c will apply "::" compression to the output.
+
+If \fIip\fR is an IPv4-mapped IPv6 address, fmt_ip6c will output it as
+IPv4 address.
+
+If \fIdest\fR equals FMT_LEN (i.e. is zero), fmt_ip6c returns the number
+of bytes it would have written.
+
+fmt_ip6c does not append \\0.
+
+For convenience, ip6.h defines the integer IP6_FMT to be big enough to
+contain every possible fmt_ip6c output plus \\0.
+.SH EXAMPLE
+#include <ip6.h>
+
+  char buf[IP6_FMT];
+  char ip[16];
+  buf[fmt_ip6c(buf,ip)]=0;
+.SH "SEE ALSO"
+fmt_ip6(3), fmt_ip6ifc(3), scan_ip6(3), fmt_ip4(3)
diff --git a/socket/fmt_ip6c.c b/socket/fmt_ip6c.c
new file mode 100644
index 0000000..64ac8de
--- /dev/null
+++ b/socket/fmt_ip6c.c
@@ -0,0 +1,13 @@
+#include "fmt.h"
+#include "byte.h"
+#include "ip4.h"
+#include "ip6.h"
+
+unsigned int fmt_ip6c(char *s,const char ip[16])
+{
+  if (ip6_isv4mapped(ip))
+    return fmt_ip4(s,ip+12);
+  else
+    return fmt_ip6(s,ip);
+}
+
diff --git a/socket/fmt_ip6if.3 b/socket/fmt_ip6if.3
new file mode 100644
index 0000000..b8fa4f7
--- /dev/null
+++ b/socket/fmt_ip6if.3
@@ -0,0 +1,35 @@
+.TH fmt_ip6if 3
+.SH NAME
+fmt_ip6if \- write a formatted ASCII representation of an IPv6 number
+.SH SYNTAX
+.B #include <ip6.h>
+
+unsigned int \fBfmt_ip6if\fP(char *\fIdest\fR,const char \fIip\fR[16],uint32 \fIscope_id\fR);
+.SH DESCRIPTION
+fmt_ip6if formats an IPv6 number in ASCII representation from \fIip\fR and
+writes the result into \fIdest\fR. It returns the number of bytes
+written.
+
+fmt_ip6if will apply "::" compression to the output.
+
+If \fIip\fR is an IPv4-mapped IPv6 address, fmt_ip6if will output the last
+4 bytes as IPv4 number in dotted-decimal notation.
+
+If \fIdest\fR equals FMT_LEN (i.e. is zero), fmt_ip6if returns the number
+of bytes it would have written.
+
+fmt_ip6 does not append \\0.
+
+ip6.h defines the integer IP6_FMT to be big enough to contain every
+possible fmt_ip6 output plus \\0.  However, for fmt_ip6if you need to
+add 1 for the '%' and IF_NAMESIZE from <net/if.h> for the interface
+name.
+.SH EXAMPLE
+#include <ip6.h>
+
+  char buf[IP6_FMT];
+  char ip[16];
+  scope_id sid;
+  buf[fmt_ip6if(buf,ip,sid)]=0;
+.SH "SEE ALSO"
+scan_ip6(3), fmt_ip4(3)
diff --git a/socket/fmt_ip6if.c b/socket/fmt_ip6if.c
new file mode 100644
index 0000000..aba677e
--- /dev/null
+++ b/socket/fmt_ip6if.c
@@ -0,0 +1,15 @@
+#include "ip6.h"
+#include "str.h"
+#include "fmt.h"
+#include "socket.h"
+
+unsigned int fmt_ip6if(char* dest,const char* ip,uint32 scope_id) {
+  int i=fmt_ip6(dest,ip);
+  if (scope_id) {
+    if (dest) {
+      dest[i]='%'; ++i; dest+=i;
+    }
+    i+=fmt_str(dest,socket_getifname(scope_id));
+  }
+  return i;
+}
diff --git a/socket/fmt_ip6ifc.3 b/socket/fmt_ip6ifc.3
new file mode 100644
index 0000000..34eb12b
--- /dev/null
+++ b/socket/fmt_ip6ifc.3
@@ -0,0 +1,35 @@
+.TH fmt_ip6ifc 3
+.SH NAME
+fmt_ip6ifc \- write a formatted ASCII representation of an IPv6 number
+.SH SYNTAX
+.B #include <ip6.h>
+
+unsigned int \fBfmt_ip6ifc\fP(char *\fIdest\fR,const char \fIip\fR[16],uint32 \fIscope_id\fR);
+.SH DESCRIPTION
+fmt_ip6ifc formats an IPv6 number in ASCII representation from \fIip\fR and
+writes the result into \fIdest\fR. It returns the number of bytes
+written.
+
+fmt_ip6ifc will apply "::" compression to the output.
+
+If \fIip\fR is an IPv4-mapped IPv6 address, fmt_ip6ifc will output it as
+IPv4 address.
+
+If \fIdest\fR equals FMT_LEN (i.e. is zero), fmt_ip6ifc returns the number
+of bytes it would have written.
+
+fmt_ip6 does not append \\0.
+
+ip6.h defines the integer IP6_FMT to be big enough to contain every
+possible fmt_ip6 output plus \\0.  However, for fmt_ip6ifc you need to
+add 1 for the '%' and IF_NAMESIZE from <net/if.h> for the interface
+name.
+.SH EXAMPLE
+#include <ip6.h>
+
+  char buf[IP6_FMT];
+  char ip[16];
+  scope_id sid;
+  buf[fmt_ip6ifc(buf,ip,sid)]=0;
+.SH "SEE ALSO"
+scan_ip6(3), fmt_ip4(3)
diff --git a/socket/fmt_ip6ifc.c b/socket/fmt_ip6ifc.c
new file mode 100644
index 0000000..51f872d
--- /dev/null
+++ b/socket/fmt_ip6ifc.c
@@ -0,0 +1,13 @@
+#include "fmt.h"
+#include "byte.h"
+#include "ip4.h"
+#include "ip6.h"
+
+unsigned int fmt_ip6ifc(char *s,const char ip[16],uint32 scope_id)
+{
+  if (ip6_isv4mapped(ip))
+    return fmt_ip4(s,ip+12);
+  else
+    return fmt_ip6if(s,ip,scope_id);
+}
+
diff --git a/socket/scan_ip6if.3 b/socket/scan_ip6if.3
new file mode 100644
index 0000000..1d60787
--- /dev/null
+++ b/socket/scan_ip6if.3
@@ -0,0 +1,41 @@
+.TH scan_ip6if 3
+.SH NAME
+scan_ip6 \- parse an IPv6 number and interface in ASCII representation
+.SH SYNTAX
+.B #include <ip6.h>
+
+int \fBscan_ip6if\fP(const char *\fIsrc\fR,char \fIip\fR[16],uint32* scope_id);
+.SH DESCRIPTION
+scan_ip6if parses an IPv6 number in RFC1884 ASCII representation
+from \fIsrc\fR and writes the result into \fIip\fR. If the IPv6 number
+is followed by the percent sign, scan_ip6if takes the word following
+that, tries to parse it as network interface and writes the result to
+\fIscope_id\fR.
+
+It returns the number of bytes read from \fIsrc\fR or 0 if the parsing
+failed.
+
+scan_ip6if accepts upper and lower case hex letters, it understands "::"
+compression and partial IPv4 addresses as in "::FFFF:129.144.52.38".
+
+To allow transparent usage of IPv4 in IPv6 applications, scan_ip6if also
+understands IPv4 addresses in dotted-decimal notation and will return
+an IPv4-mapped IPv6 address (i.e. "127.0.0.1" will be parsed as
+"::FFFF:127.0.0.1".
+
+Unlike many other IP parsing routines, scan_ip6if does not recognize octal
+(like \fB0177.0.0.1\fR) or hexadecimal numbers (like \fB0x7f000001\fR)
+in the IPv4 part.
+.SH EXAMPLE
+#include <str.h>
+.br
+#include <ip6.h>
+
+  char buf[]="::1%lo";
+  char ip[16];
+  uint32 scope_id;
+  if (scan_ip6if(buf,ip,&scope_id) != str_len(buf))
+    parse_error();
+
+.SH "SEE ALSO"
+fmt_ip6(3), scan_ip4(3), fmt_ip6if(3)
diff --git a/socket/scan_ip6if.c b/socket/scan_ip6if.c
new file mode 100644
index 0000000..ec1a794
--- /dev/null
+++ b/socket/scan_ip6if.c
@@ -0,0 +1,29 @@
+#include "ip6.h"
+#include "byte.h"
+#include <ctype.h>
+#include "socket.h"
+#if defined(__linux__)
+#include <alloca.h>
+#endif
+
+unsigned int scan_ip6if(const char* src,char* ip,uint32* scope_id) {
+  int i=scan_ip6(src,ip);
+  *scope_id=0;
+  if (src[i]=='%') {
+    int j;
+    char* tmp;
+    for (j=i+1; isalnum(src[j]); ++j) ;
+    if (!src[j])
+      tmp=(char*)src+i+1;
+    else {
+      tmp=alloca(j-i);
+      byte_copy(tmp,j-(i+1),src+i+1);
+      tmp[j-(i+1)]=0;
+    }
+    if (*tmp) {
+      *scope_id=socket_getifidx(tmp);
+      return j;
+    }
+  }
+  return i;
+}
diff --git a/socket/socket_getifname.c b/socket/socket_getifname.c
index 21b4514..1902fd5 100644
--- a/socket/socket_getifname.c
+++ b/socket/socket_getifname.c
@@ -7,7 +7,7 @@
 #include "haven2i.h"
 
 #ifdef HAVE_N2I
-static char ifname[IFNAMSIZ];
+static char ifname[IF_NAMESIZE];
 
 const char* socket_getifname(uint32 _interface) {
   char *tmp=if_indextoname(_interface,ifname);
diff --git a/t.c b/t.c
index 8e3db16..68aece6 100644
--- a/t.c
+++ b/t.c
@@ -18,16 +18,31 @@
 #include <unistd.h>
 #include <errno.h>
 #include <string.h>
+#include <assert.h>
 
 #define rdtscl(low) \
      __asm__ __volatile__ ("rdtsc" : "=a" (low) : : "edx")
 
 int main(int argc,char* argv[]) {
+  char buf[IP6_FMT+100];
+  int i;
+  char ip[16];
+  uint32 scope_id;
+  char* s="fec0::1:220:e0ff:fe69:ad92%eth0/64";
+  char blubip[16]="\0\0\0\0\0\0\0\0\0\0\xff\xff\x7f\0\0\001";
+  i=scan_ip6if(s,ip,&scope_id);
+  assert(s[i]=='/');
+  buffer_put(buffer_1,buf,fmt_ip6if(buf,ip,scope_id));
+  buffer_putnlflush(buffer_1);
+  buffer_put(buffer_1,buf,fmt_ip6ifc(buf,blubip,scope_id));
+  buffer_putnlflush(buffer_1);
+#if 0
   char buf[100];
   int i;
   printf("%d\n",i=fmt_pad(buf,"fnord",5,7,10));
   buf[i]=0;
   puts(buf);
+#endif
 #if 0
   char ip[16];
   char buf[32];