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Diffstat (limited to 'conf.c')
-rw-r--r--conf.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/conf.c b/conf.c
index fd8f3cf..2622a38 100644
--- a/conf.c
+++ b/conf.c
@@ -617,7 +617,9 @@ static void usage(const char *name)
info(" /tmp/passt_ISO8601-TIMESTAMP_INSTANCE-NUMBER.pcap");
info( " -m, --mtu MTU Assign MTU via DHCP/NDP");
- info( " default: no MTU assigned via DHCP/NDP options");
+ info( " a zero value disables assignment");
+ info( " default: 65520: maximum 802.3 MTU minus 802.3 header");
+ info( " length, rounded to 32 bits (IPv4 words)");
info( " -a, --address ADDR Assign IPv4 or IPv6 address ADDR");
info( " can be specified zero to two times (for IPv4 and IPv6)");
info( " default: use addresses from interface with default route");
@@ -954,6 +956,12 @@ void conf(struct ctx *c, int argc, char **argv)
errno = 0;
c->mtu = strtol(optarg, NULL, 0);
+
+ if (!c->mtu) {
+ c->mtu = -1;
+ break;
+ }
+
if (c->mtu < ETH_MIN_MTU || c->mtu > (int)ETH_MAX_MTU ||
errno) {
err("Invalid MTU: %s", optarg);
@@ -1132,6 +1140,11 @@ void conf(struct ctx *c, int argc, char **argv)
}
}
+ if (!c->mtu) {
+ c->mtu = (ETH_MAX_MTU - ETH_HLEN) /
+ sizeof(uint32_t) * sizeof(uint32_t);
+ }
+
get_routes(c);
get_addrs(c);