diff --git a/soc/runtime/Makefile b/soc/runtime/Makefile
index 1b95bd727..a27e651f8 100644
--- a/soc/runtime/Makefile
+++ b/soc/runtime/Makefile
@@ -1,6 +1,6 @@
 include $(MSCDIR)/software/common.mak
 
-OBJECTS := isr.o flash_storage.o clock.o elf_loader.o services.o session.o log.o test_mode.o kloader.o mailbox.o ksupport_data.o main.o
+OBJECTS := isr.o flash_storage.o clock.o elf_loader.o services.o session.o log.o test_mode.o kloader.o mailbox.o ksupport_data.o kserver.o main.o
 OBJECTS_KSUPPORT := ksupport.o exception_jmp.o exceptions.o mailbox.o bridge.o rtio.o dds.o
 
 CFLAGS += -Ilwip/src/include -Iliblwip
diff --git a/soc/runtime/kserver.c b/soc/runtime/kserver.c
new file mode 100644
index 000000000..4d75da8bc
--- /dev/null
+++ b/soc/runtime/kserver.c
@@ -0,0 +1,215 @@
+#include <generated/csr.h>
+
+#ifdef CSR_ETHMAC_BASE
+
+#include <netif/etharp.h>
+#include <netif/liteethif.h>
+#include <lwip/init.h>
+#include <lwip/memp.h>
+#include <lwip/ip4_addr.h>
+#include <lwip/ip4.h>
+#include <lwip/netif.h>
+#include <lwip/sys.h>
+#include <lwip/tcp.h>
+#include <lwip/timers.h>
+
+#include "session.h"
+#include "kserver.h"
+
+struct kserver_connstate {
+    int magic_recognized;
+    struct pbuf *rp;
+    int rp_offset;
+};
+
+static struct kserver_connstate *cs_new(void)
+{
+    struct kserver_connstate *cs;
+
+    cs = (struct kserver_connstate *)mem_malloc(sizeof(struct kserver_connstate));
+    if(!cs)
+        return NULL;
+    cs->magic_recognized = 0;
+    cs->rp = NULL;
+    cs->rp_offset = 0;
+    return cs;
+}
+
+static void cs_free(struct kserver_connstate *cs)
+{
+    if(cs->rp)
+        pbuf_free(cs->rp);
+    mem_free(cs);
+}
+
+static const char kserver_magic[] = "ARTIQ coredev\n";
+
+static int magic_ok(struct kserver_connstate *cs)
+{
+    return cs->magic_recognized >= 14;
+}
+
+static struct kserver_connstate *active_cs;
+static struct tcp_pcb *active_pcb;
+
+static void kserver_close(struct kserver_connstate *cs, struct tcp_pcb *pcb)
+{
+    if(cs == active_cs) {
+        session_end();
+        active_cs = NULL;
+        active_pcb = NULL;
+    }
+
+    /* lwip loves to call back with broken pointers. Prevent that. */
+    tcp_arg(pcb, NULL);
+    tcp_recv(pcb, NULL);
+    tcp_sent(pcb, NULL);
+    tcp_err(pcb, NULL);
+
+    cs_free(cs);
+    tcp_close(pcb);
+}
+
+static err_t kserver_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
+{
+    struct kserver_connstate *cs;
+
+    cs = (struct kserver_connstate *)arg;
+    if(p) {
+        if(cs->rp)
+            pbuf_cat(cs->rp, p);
+        else {
+            cs->rp = p;
+            cs->rp_offset = 0;
+        }
+    } else
+        kserver_close(cs, pcb);
+    return ERR_OK;
+}
+
+static err_t kserver_sent(void *arg, struct tcp_pcb *pcb, u16_t len)
+{
+    session_ack_mem(len);
+    return ERR_OK;
+}
+
+static void tcp_pcb_service(void *arg, struct tcp_pcb *pcb)
+{
+    struct kserver_connstate *cs;
+    int remaining_in_pbuf;
+    char *rpp;
+    struct pbuf *next;
+    int r;
+
+    cs = (struct kserver_connstate *)arg;
+
+    while(cs->rp) {
+        remaining_in_pbuf = cs->rp->len - cs->rp_offset;
+        rpp = (char *)cs->rp->payload;
+        while(remaining_in_pbuf > 0) {
+            if(cs == active_cs) {
+                r = session_input(&rpp[cs->rp_offset], remaining_in_pbuf);
+                if(r > 0) {
+                    tcp_recved(pcb, r);
+                    cs->rp_offset += r;
+                    remaining_in_pbuf -= r;
+                } else if(r == 0)
+                    return;
+                else
+                    kserver_close(cs, pcb);
+            } else {
+                if(rpp[cs->rp_offset] == kserver_magic[cs->magic_recognized]) {
+                    cs->magic_recognized++;
+                    if(magic_ok(cs)) {
+                        if(active_cs)
+                            kserver_close(active_cs, active_pcb);
+                        session_start();
+                        active_cs = cs;
+                        active_pcb = pcb;
+                        tcp_sent(pcb, kserver_sent);
+                    }
+                } else {
+                    kserver_close(cs, pcb);
+                    return;
+                }
+                remaining_in_pbuf--;
+                cs->rp_offset++;
+                tcp_recved(pcb, 1);
+            }
+        }
+        next = cs->rp->next;
+        if(cs->rp->tot_len != cs->rp->len) {
+            pbuf_ref(next);
+            pbuf_free(cs->rp);
+            cs->rp = next;
+            cs->rp_offset = 0;
+        } else {
+            pbuf_free(cs->rp);
+            cs->rp = NULL;
+        }
+    }
+}
+
+static void kserver_err(void *arg, err_t err)
+{
+    struct kserver_connstate *cs;
+
+    cs = (struct kserver_connstate *)arg;
+    cs_free(cs);
+}
+
+static struct tcp_pcb *listen_pcb;
+
+static err_t kserver_accept(void *arg, struct tcp_pcb *newpcb, err_t err)
+{
+    struct kserver_connstate *cs;
+
+    cs = cs_new();
+    if(!cs)
+        return ERR_MEM;
+    tcp_accepted(listen_pcb);
+    tcp_arg(newpcb, cs);
+    tcp_recv(newpcb, kserver_recv);
+    tcp_err(newpcb, kserver_err);
+    return ERR_OK;
+}
+
+void kserver_init(void)
+{
+    listen_pcb = tcp_new();
+    tcp_bind(listen_pcb, IP_ADDR_ANY, 1381);
+    listen_pcb = tcp_listen(listen_pcb);
+    tcp_accept(listen_pcb, kserver_accept);
+}
+
+extern struct tcp_pcb *tcp_active_pcbs;
+
+void kserver_service(void)
+{
+    struct tcp_pcb *pcb;
+    void *data;
+    int len, sndbuf;
+
+    /* Assume all active TCP PCBs with a non-NULL arg are our connections. */
+    pcb = tcp_active_pcbs;
+    while(pcb) {
+        if(pcb->callback_arg)
+            tcp_pcb_service(pcb->callback_arg, pcb);
+        pcb = pcb->next;
+    }
+
+    if(active_cs) {
+        session_poll(&data, &len);
+        if(len > 0) {
+            sndbuf = tcp_sndbuf(active_pcb);
+            if(len > sndbuf)
+                len = sndbuf;
+            tcp_write(active_pcb, data, len, 0);
+            session_ack_data(len);
+        }
+        if(len < 0)
+            kserver_close(active_cs, active_pcb);
+    }
+}
+
+#endif /* CSR_ETHMAC_BASE */
diff --git a/soc/runtime/kserver.h b/soc/runtime/kserver.h
new file mode 100644
index 000000000..28eb79ecc
--- /dev/null
+++ b/soc/runtime/kserver.h
@@ -0,0 +1,7 @@
+#ifndef __KSERVER_H
+#define __KSERVER_H
+
+void kserver_init(void);
+void kserver_service(void);
+
+#endif /* __KSERVER_H */
diff --git a/soc/runtime/main.c b/soc/runtime/main.c
index 29a4fc378..f6facbdd0 100644
--- a/soc/runtime/main.c
+++ b/soc/runtime/main.c
@@ -21,12 +21,13 @@
 #include <lwip/timers.h>
 #endif
 
+#include "flash_storage.h"
 #include "clock.h"
 #include "test_mode.h"
+#include "kserver.h"
 #include "session.h"
 
 #ifdef CSR_ETHMAC_BASE
-unsigned char macadr[6] = {0x10, 0xe2, 0xd5, 0x00, 0x00, 0x00};
 
 u32_t sys_now(void)
 {
@@ -44,15 +45,69 @@ static void lwip_service(void)
     }
 }
 
+unsigned char macadr[6];
+
+static int hex2nib(int c)
+{
+    if((c >= '0') && (c <= '9'))
+        return c - '0';
+    if((c >= 'a') && (c <= 'f'))
+        return c - 'a' + 10;
+    if((c >= 'A') && (c <= 'F'))
+        return c - 'A' + 10;
+    return -1;
+}
+
+static void init_macadr(void)
+{
+    static const unsigned char default_macadr[6] = {0x10, 0xe2, 0xd5, 0x32, 0x50, 0x00};
+    char b[32];
+    char fs_macadr[6];
+    int i, r, s;
+
+    memcpy(macadr, default_macadr, 6);
+    r = fs_read("mac", b, sizeof(b) - 1, NULL);
+    if(r <= 0)
+        return;
+    b[r] = 0;
+    for(i=0;i<6;i++) {
+        r = hex2nib(b[3*i]);
+        s = hex2nib(b[3*i + 1]);
+        if((r < 0) || (s < 0))
+            return;
+        fs_macadr[i] = (r << 4) | s;
+    }
+    for(i=0;i<5;i++)
+        if(b[3*i + 2] != ':')
+            return;
+    memcpy(macadr, fs_macadr, 6);
+}
+
+static void fsip_or_default(struct ip4_addr *d, char *key, int i1, int i2, int i3, int i4)
+{
+    int r;
+    char cp[32];
+
+    IP4_ADDR(d, i1, i2, i3, i4);
+
+    r = fs_read(key, cp, sizeof(cp) - 1, NULL);
+    if(r <= 0)
+        return;
+    cp[r] = 0;
+    if(!ip4addr_aton(cp, d))
+        return;
+}
+
 static void network_init(void)
 {
     struct ip4_addr local_ip;
     struct ip4_addr netmask;
     struct ip4_addr gateway_ip;
 
-    IP4_ADDR(&local_ip, 192, 168, 0, 42);
-    IP4_ADDR(&netmask, 255, 255, 255, 0);
-    IP4_ADDR(&gateway_ip, 192, 168, 0, 1);
+    init_macadr();
+    fsip_or_default(&local_ip, "ip", 192, 168, 0, 42);
+    fsip_or_default(&netmask, "netmask", 255, 255, 255, 0);
+    fsip_or_default(&gateway_ip, "gateway", 192, 168, 0, 1);
 
     lwip_init();
 
@@ -62,204 +117,9 @@ static void network_init(void)
     netif_set_link_up(&netif);
 }
 
-struct kserver_connstate {
-    int magic_recognized;
-    struct pbuf *rp;
-    int rp_offset;
-};
-
-static struct kserver_connstate *cs_new(void)
-{
-    struct kserver_connstate *cs;
-
-    cs = (struct kserver_connstate *)mem_malloc(sizeof(struct kserver_connstate));
-    if(!cs)
-        return NULL;
-    cs->magic_recognized = 0;
-    cs->rp = NULL;
-    cs->rp_offset = 0;
-    return cs;
-}
-
-static void cs_free(struct kserver_connstate *cs)
-{
-    if(cs->rp)
-        pbuf_free(cs->rp);
-    mem_free(cs);
-}
-
-static const char kserver_magic[] = "ARTIQ coredev\n";
-
-static int magic_ok(struct kserver_connstate *cs)
-{
-    return cs->magic_recognized >= 14;
-}
-
-static struct kserver_connstate *active_cs;
-static struct tcp_pcb *active_pcb;
-
-static void kserver_close(struct kserver_connstate *cs, struct tcp_pcb *pcb)
-{
-    if(cs == active_cs) {
-        session_end();
-        active_cs = NULL;
-        active_pcb = NULL;
-    }
-
-    /* lwip loves to call back with broken pointers. Prevent that. */
-    tcp_arg(pcb, NULL);
-    tcp_recv(pcb, NULL);
-    tcp_sent(pcb, NULL);
-    tcp_err(pcb, NULL);
-
-    cs_free(cs);
-    tcp_close(pcb);
-}
-
-static err_t kserver_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
-{
-    struct kserver_connstate *cs;
-
-    cs = (struct kserver_connstate *)arg;
-    if(p) {
-        if(cs->rp)
-            pbuf_cat(cs->rp, p);
-        else {
-            cs->rp = p;
-            cs->rp_offset = 0;
-        }
-    } else
-        kserver_close(cs, pcb);
-    return ERR_OK;
-}
-
-static err_t kserver_sent(void *arg, struct tcp_pcb *pcb, u16_t len)
-{
-    session_ack_mem(len);
-    return ERR_OK;
-}
-
-static void tcp_pcb_service(void *arg, struct tcp_pcb *pcb)
-{
-    struct kserver_connstate *cs;
-    int remaining_in_pbuf;
-    char *rpp;
-    struct pbuf *next;
-    int r;
-
-    cs = (struct kserver_connstate *)arg;
-
-    while(cs->rp) {
-        remaining_in_pbuf = cs->rp->len - cs->rp_offset;
-        rpp = (char *)cs->rp->payload;
-        while(remaining_in_pbuf > 0) {
-            if(cs == active_cs) {
-                r = session_input(&rpp[cs->rp_offset], remaining_in_pbuf);
-                if(r > 0) {
-                    tcp_recved(pcb, r);
-                    cs->rp_offset += r;
-                    remaining_in_pbuf -= r;
-                } else if(r == 0)
-                    return;
-                else
-                    kserver_close(cs, pcb);
-            } else {
-                if(rpp[cs->rp_offset] == kserver_magic[cs->magic_recognized]) {
-                    cs->magic_recognized++;
-                    if(magic_ok(cs)) {
-                        if(active_cs)
-                            kserver_close(active_cs, active_pcb);
-                        session_start();
-                        active_cs = cs;
-                        active_pcb = pcb;
-                        tcp_sent(pcb, kserver_sent);
-                    }
-                } else {
-                    kserver_close(cs, pcb);
-                    return;
-                }
-                remaining_in_pbuf--;
-                cs->rp_offset++;
-                tcp_recved(pcb, 1);
-            }
-        }
-        next = cs->rp->next;
-        if(cs->rp->tot_len != cs->rp->len) {
-            pbuf_ref(next);
-            pbuf_free(cs->rp);
-            cs->rp = next;
-            cs->rp_offset = 0;
-        } else {
-            pbuf_free(cs->rp);
-            cs->rp = NULL;
-        }
-    }
-}
-
-static void kserver_err(void *arg, err_t err)
-{
-    struct kserver_connstate *cs;
-
-    cs = (struct kserver_connstate *)arg;
-    cs_free(cs);
-}
-
-static struct tcp_pcb *listen_pcb;
-
-static err_t kserver_accept(void *arg, struct tcp_pcb *newpcb, err_t err)
-{
-    struct kserver_connstate *cs;
-
-    cs = cs_new();
-    if(!cs)
-        return ERR_MEM;
-    tcp_accepted(listen_pcb);
-    tcp_arg(newpcb, cs);
-    tcp_recv(newpcb, kserver_recv);
-    tcp_err(newpcb, kserver_err);
-    return ERR_OK;
-}
-
-static void kserver_init(void)
-{
-    listen_pcb = tcp_new();
-    tcp_bind(listen_pcb, IP_ADDR_ANY, 1381);
-    listen_pcb = tcp_listen(listen_pcb);
-    tcp_accept(listen_pcb, kserver_accept);
-}
-
-extern struct tcp_pcb *tcp_active_pcbs;
-
-static void kserver_service(void)
-{
-    struct tcp_pcb *pcb;
-    void *data;
-    int len, sndbuf;
-
-    /* Assume all active TCP PCBs with a non-NULL arg are our connections. */
-    pcb = tcp_active_pcbs;
-    while(pcb) {
-        if(pcb->callback_arg)
-            tcp_pcb_service(pcb->callback_arg, pcb);
-        pcb = pcb->next;
-    }
-
-    if(active_cs) {
-        session_poll(&data, &len);
-        if(len > 0) {
-            sndbuf = tcp_sndbuf(active_pcb);
-            if(len > sndbuf)
-                len = sndbuf;
-            tcp_write(active_pcb, data, len, 0);
-            session_ack_data(len);
-        }
-        if(len < 0)
-            kserver_close(active_cs, active_pcb);
-    }
-}
-
 static void regular_main(void)
 {
+    puts("Accepting sessions on Ethernet");
     clock_init();
     network_init();
     kserver_init();
@@ -317,6 +177,7 @@ static void serial_service(void)
 
 static void regular_main(void)
 {
+    puts("Accepting sessions on serial link");
     clock_init();
 
     /* Open the session for the serial control. */
@@ -369,12 +230,6 @@ int main(void)
 
     puts("ARTIQ runtime built "__DATE__" "__TIME__"\n");
 
-#ifdef CSR_ETHMAC_BASE
-    puts("Accepting sessions on Ethernet");
-#else
-    puts("Accepting sessions on serial link");
-#endif
-
     puts("Press 't' to enter test mode...");
     blink_led();