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9
README.md
View File

@ -133,11 +133,4 @@ On some versions of Raspbian (and probably other operating systems), the DHCP cl
# of /etc/dhcpcd.conf to prevent dhcpcd from changing MTU # of /etc/dhcpcd.conf to prevent dhcpcd from changing MTU
denyinterfaces tnc0 denyinterfaces tnc0
``` ```
## Support tncattach development
You can help support the continued development of open, free and private communications systems by donating via one of the following channels:
- Ethereum: 0x81F7B979fEa6134bA9FD5c701b3501A2e61E897a
- Bitcoin: 3CPmacGm34qYvR6XWLVEJmi2aNe3PZqUuq
- Ko-Fi: https://ko-fi.com/markqvist

110
TAP.c
View File

@ -5,72 +5,15 @@ char tap_name[IFNAMSIZ];
extern bool verbose; extern bool verbose;
extern bool noipv6; extern bool noipv6;
extern bool set_ipv4; extern bool set_ipv4;
extern bool set_ipv6;
extern bool set_linklocal;
extern bool set_netmask; extern bool set_netmask;
extern bool noup; extern bool noup;
extern int mtu; extern int mtu;
extern int device_type; extern int device_type;
extern char if_name[IFNAMSIZ]; extern char if_name[IFNAMSIZ];
extern char* ipv4_addr; extern char* ipv4_addr;
extern char* ipv6_addr;
extern long ipv6_prefixLen;
extern char* netmask; extern char* netmask;
extern void cleanup(); extern void cleanup();
void trySixSet
(
int interfaceIndex,
struct in6_addr address,
int prefixLen
)
{
char ip_str[INET6_ADDRSTRLEN+1];
inet_ntop(AF_INET6, &address, ip_str, INET6_ADDRSTRLEN+1);
printf
(
"Adding IPv6 address of '%s/%d' to interface at if_index %d\n",
ip_str,
prefixLen,
interfaceIndex
);
int inet6 = socket(AF_INET6, SOCK_DGRAM, 0);
if(inet6 < 0)
{
printf("Error opening control socket for adding IPv6 address to interface\n");
cleanup();
exit(1);
}
struct in6_ifreq paramReq;
memset(&paramReq, 0, sizeof(struct in6_ifreq));
paramReq.ifr6_ifindex = interfaceIndex;
paramReq.ifr6_prefixlen = prefixLen;
paramReq.ifr6_addr = address;
// Try add the address
if(ioctl(inet6, SIOCSIFADDR, &paramReq) < 0)
{
printf
(
"There was an errror assigning address '%s/%d' to if_index %d\n",
ip_str,
prefixLen,
interfaceIndex
);
cleanup();
close(inet6);
exit(1);
}
printf("Address '%s/%d' added\n", ip_str, prefixLen);
close(inet6);
}
int open_tap(void) { int open_tap(void) {
struct ifreq ifr; struct ifreq ifr;
int fd = open("/dev/net/tun", O_RDWR); int fd = open("/dev/net/tun", O_RDWR);
@ -100,11 +43,10 @@ int open_tap(void) {
exit(1); exit(1);
} else { } else {
strcpy(if_name, ifr.ifr_name); strcpy(if_name, ifr.ifr_name);
int inet = socket(AF_INET, SOCK_DGRAM, 0); int inet = socket(AF_INET, SOCK_DGRAM, 0);
if (inet == -1) { if (inet == -1) {
perror("Could not open control socket"); perror("Could not open AF_INET socket");
cleanup(); cleanup();
exit(1); exit(1);
} else { } else {
@ -240,54 +182,6 @@ int open_tap(void) {
} }
} }
} }
if(set_ipv6 || set_linklocal)
{
// Firstly, obtain the interface index by `ifr_name`
int inet6 = socket(AF_INET6, SOCK_DGRAM, 0);
if(inet6 < 0)
{
printf("Error opening control socket for adding IPv6 address to interface\n");
cleanup();
exit(1);
}
if(ioctl(inet6, SIOCGIFINDEX, &ifr) < 0)
{
printf("Could not get interface index for interface '%s'\n", ifr.ifr_name);
close(inet6);
cleanup();
exit(1);
}
// if link-local was NOT requested and interface
// has been up'd -> then kernel would have added
// a link-local already, this removes it
if(!set_linklocal & !noup)
{
// TODO: Get all addresses that start with fe80
}
// Else it could have been no-up; hence you will have to remove
// the link-local yourself
// Other else is link-local was requested, then we don't care (whether
// up'd or not as it will inevitably be added by the kernel)
// Convert ASCII IPv6 address to ABI structure
struct in6_addr six_addr_itself;
memset(&six_addr_itself, 0, sizeof(struct in6_addr));
if(inet_pton(AF_INET6, ipv6_addr, &six_addr_itself) < 0)
{
printf("Error parsing IPv6 address '%s'\n", ipv6_addr);
close(inet6);
cleanup();
exit(1);
}
// Add user's requested address
trySixSet(ifr.ifr_ifindex, six_addr_itself, ipv6_prefixLen);
close(inet6);
}
} }
} }
} }
@ -301,4 +195,4 @@ int open_tap(void) {
int close_tap(int tap_fd) { int close_tap(int tap_fd) {
return close(tap_fd); return close(tap_fd);
} }

1
TAP.h
View File

@ -9,7 +9,6 @@
#include <linux/if_tun.h> #include <linux/if_tun.h>
#include <sys/socket.h> #include <sys/socket.h>
#include <arpa/inet.h> #include <arpa/inet.h>
#include <linux/ipv6.h>
#include "Constants.h" #include "Constants.h"
int open_tap(void); int open_tap(void);

25
makefile
View File

@ -1,35 +1,26 @@
.DEFAULT_GOAL := all .DEFAULT_GOAL := all
.PHONY: all clean install uninstall tncattach .PHONY: all clean install uninstall tncattach
RM ?= rm compiler = gcc
INSTALL ?= install flags = -Wall -std=gnu11 -static-libgcc
CC ?= gcc
CFLAGS ?= -Wall -std=gnu11 -static-libgcc
LDFLAGS ?=
PREFIX ?= /usr/local
all: tncattach all: tncattach
rebuild: clean all rebuild: clean all
clean: clean:
@echo "Cleaning tncattach build..." @echo "Cleaning tncattach build..."
$(RM) -f tncattach @rm -f tncattach
tncattach: tncattach:
@echo "Making tncattach..." @echo "Making tncattach..."
@echo "Compiling with: $(CC)" @echo "Compiling with: ${compiler}"
$(CC) $(CFLAGS) $(LDFLAGS) tncattach.c Serial.c TCP.c KISS.c TAP.c -o tncattach ${compiler} ${flags} tncattach.c Serial.c TCP.c KISS.c TAP.c -o tncattach -Wall
install: install:
@echo "Installing tncattach..." @echo "Installing tncattach..."
$(INSTALL) -d $(DESTDIR)/$(PREFIX)/bin chmod a+x tncattach
$(INSTALL) -Dm755 tncattach $(DESTDIR)/$(PREFIX)/bin/tncattach cp ./tncattach /usr/local/sbin/
@echo "Installing man page..."
gzip -9 tncattach.8
$(INSTALL) -d $(DESTDIR)/$(PREFIX)/share/man/man8
$(INSTALL) -Dm644 tncattach.8.gz $(DESTDIR)/$(PREFIX)/share/man/man8/tncattach.8.gz
uninstall: uninstall:
@echo "Uninstalling tncattach" @echo "Uninstalling tncattach"
$(RM) $(DESTDIR)/$(PREFIX)/bin/tncattach rm /usr/local/sbin/tncattach
$(RM) $(DESTDIR)/$(PREFIX)/share/man/man8/tncattach.8.gz

165
tncattach.8
View File

@ -1,165 +0,0 @@
.TH tncattach 8 "September 12, 2020"
.SH NAME
.
.
tncattach \- Attach TNC devices as system network interfaces
.SH SYNOPSIS
.
.
\f[B]tncattach\f[R] [OPTION...] port baudrate
.SH DESCRIPTION
Attach KISS TNC devices as network interfaces in Linux. This program allows you to attach TNCs or any KISS-compatible device as a network interface. This program does not need any kernel modules, and has no external dependencies outside the standard Linux and GNU C libraries.
.SH OPTIONS
.
.
.TP
.BI \-m, \-\-mtu=MTU
.
Specify interface MTU
.
.
.TP
.BI \-e, \-\-ethernet
Create a full ethernet device
.
.
.TP
.BI \-i, \-\-ipv4=IP_ADDRESS
Configure an IPv4 address on interface
.
.
.TP
.BI \-n, \-\-noipv6
Filter IPv6 traffic from reaching TNC
.
.
.TP
.BI \-\-noup
Only create interface, don't bring it up
.
.
.TP
.BI \-T, \-\-kisstcp
Use KISS over TCP instead of serial port
.
.
.TP
.BI \-H, \-\-tcphost=TCP_HOST
Host to connect to when using KISS over TCP
.
.
.TP
.BI \-P, \-\-tcpport=TCP_PORT
TCP port when using KISS over TCP
.
.
.TP
.BI \-t, \-\-interval=SECONDS
Maximum interval between station identifications
.
.
.TP
.B \-s, \-\-id=CALLSIGN
Station identification data
.
.
.TP
.BI \-d, \-\-daemon
Run tncattach as a daemon
.
.
.TP
.BI \-v, \-\-verbose
Enable verbose output
.
.
.TP
.BI \-?, \-\-help
Show help
.
.
.TP
.BI \-\-usage
Give a short usage message
.
.
.TP
.BI \-V, \-\-version
Print program version
.
.
.SH USAGE
The program supports attaching TNCs as point-to-point tunnel devices, or generic ethernet devices. The ethernet mode is suitable for point-to-multipoint setups, and can be enabled with the corresponding command line switch. If you only need point-to-point links, it is advisable to just use the standard point-to-point mode, since it doesn't incur the ethernet header overhead on each packet.
.P
If you want to connect to a virtual KISS TNC over a TCP connection, you can use the -T option, along with the -H and -P options to specify the host and port.
.P
Additionally, it is worth noting that tncattach can filter out IPv6 packets from reaching the TNC. Most operating systems attempts to autoconfigure IPv6 when an interface is brought up, which results in a substantial amount of IPv6 traffic generated by router solicitations and similar, which is usually unwanted for packet radio links and similar.
.P
If you intend to use tncattach on a system with mDNS services enabled (avahi-daemon, for example), you may want to consider modifying your mDNS setup to exclude TNC interfaces, or turning it off entirely, since it will generate a lot of traffic that might be unwanted.
.SH STATION IDENTIFICATION
You can configure tncattach to automatically transmit station identification beacons according to a given interval, by using the --id and --interval options. Identification will be transmitted as raw data frames with whatever content has been specified in the --id option. Useful for amateur radio use, or other areas where station identification is necessary.
.P
Identification beacons will be transmitted when:
.P
.IP
There is outgoing data to send, and the specified interval has elapsed.
.IP
The specified interval elapses, and data has been sent since the last ID beacon.
.IP
The program exits, if any data frames have been transmitted since the last ID beacon.
.P
The above methodology should comply with station identification rules for amateur radio in most parts of the world, and complies with US Part 97 rules.
.SH EXAMPLES
.
Create an ethernet device with a USB-connected TNC, set the MTU, filter IPv6 traffic, and set an IPv4 address:
.IP
sudo tncattach /dev/ttyUSB0 115200 --ethernet --mtu 576 --noipv6 --ipv4 10.92.0.10/24
.P
Create an ethernet device with a TCP-connected TNC, set the MTU, filter IPv6 traffic, and set an IPv4 address:
.IP
sudo tncattach -T -H localhost -P 8001 --ethernet --mtu 576 --noipv6 --ipv4 10.92.0.10/24
.P
You can interact with the interface like any other using the ip or ifconfig utilities.
.p
Check interface is running:
.P
# ifconfig
.br
tnc0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 400
.br
inet 10.93.0.1 netmask 255.255.255.255 destination 10.93.0.2
.br
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 500 (UNSPEC)
.br
RX packets 0 bytes 0 (0.0 B)
.br
RX errors 0 dropped 0 overruns 0 frame 0
.br
TX packets 0 bytes 0 (0.0 B)
.br
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
.P
.SH WORTH KNOWING ON RASPBIAN
On some versions of Raspbian (and probably other operating systems), the DHCP client daemon dhcpcd interferes with TNC interfaces, by overriding their MTU and trying to auto-configure link-local addresses. You probably don't want this, and it can be disabled by editing the /etc/dhcpcd.conf file, adding a statement telling dhcpcd to ignore your TNC interface:
.P
# Add the following statement somewhere at the beginning
.br
# of /etc/dhcpcd.conf to prevent dhcpcd from changing MTU
.br
denyinterfaces tnc0
.SH SEE ALSO
rnodeconfigutil(8)
.SH AUTHOR
Mark Qvist

106
tncattach.c
View File

@ -34,16 +34,11 @@ bool noipv6 = false;
bool noup = false; bool noup = false;
bool daemonize = false; bool daemonize = false;
bool set_ipv4 = false; bool set_ipv4 = false;
bool set_ipv6 = false;
bool set_linklocal = false;
bool set_netmask = false; bool set_netmask = false;
bool kiss_over_tcp = false; bool kiss_over_tcp = false;
char* ipv4_addr; char* ipv4_addr;
char* netmask; char* netmask;
char* ipv6_addr;
long ipv6_prefixLen;
char* tcp_host; char* tcp_host;
int tcp_port; int tcp_port;
@ -266,7 +261,7 @@ void read_loop(void) {
exit(1); exit(1);
} }
const char *argp_program_version = "tncattach 0.1.9"; const char *argp_program_version = "tncattach 0.1.8";
const char *argp_program_bug_address = "<mark@unsigned.io>"; const char *argp_program_bug_address = "<mark@unsigned.io>";
static char doc[] = "\r\nAttach TNC devices as system network interfaces\vTo attach the TNC connected to /dev/ttyUSB0 as an ethernet device with an MTU of 512 bytes and assign an IPv4 address, while filtering IPv6 traffic, use:\r\n\r\n\ttncattach /dev/ttyUSB0 115200 -m 512 -e --noipv6 --ipv4 10.0.0.1/24\r\n\r\nStation identification can be performed automatically to comply with Part 97 rules. See the README for a complete description. Use the --id and --interval options, which should commonly be set to your callsign, and 600 seconds."; static char doc[] = "\r\nAttach TNC devices as system network interfaces\vTo attach the TNC connected to /dev/ttyUSB0 as an ethernet device with an MTU of 512 bytes and assign an IPv4 address, while filtering IPv6 traffic, use:\r\n\r\n\ttncattach /dev/ttyUSB0 115200 -m 512 -e --noipv6 --ipv4 10.0.0.1/24\r\n\r\nStation identification can be performed automatically to comply with Part 97 rules. See the README for a complete description. Use the --id and --interval options, which should commonly be set to your callsign, and 600 seconds.";
static char args_doc[] = "port baudrate"; static char args_doc[] = "port baudrate";
@ -274,17 +269,15 @@ static struct argp_option options[] = {
{ "mtu", 'm', "MTU", 0, "Specify interface MTU", 1}, { "mtu", 'm', "MTU", 0, "Specify interface MTU", 1},
{ "ethernet", 'e', 0, 0, "Create a full ethernet device", 2}, { "ethernet", 'e', 0, 0, "Create a full ethernet device", 2},
{ "ipv4", 'i', "IP_ADDRESS", 0, "Configure an IPv4 address on interface", 3}, { "ipv4", 'i', "IP_ADDRESS", 0, "Configure an IPv4 address on interface", 3},
{ "ipv6", '6', "IP6_ADDRESS", 0, "Configure an IPv6 address on interface", 4}, { "noipv6", 'n', 0, 0, "Filter IPv6 traffic from reaching TNC", 4},
{ "ll", 'l', 0, 0, "Add a link-local Ipv6 address", 5}, { "noup", 1, 0, 0, "Only create interface, don't bring it up", 5},
{ "noipv6", 'n', 0, 0, "Filter IPv6 traffic from reaching TNC", 6}, { "kisstcp", 'T', 0, 0, "Use KISS over TCP instead of serial port", 6},
{ "noup", 1, 0, 0, "Only create interface, don't bring it up", 7}, { "tcphost", 'H', "TCP_HOST", 0, "Host to connect to when using KISS over TCP", 7},
{ "kisstcp", 'T', 0, 0, "Use KISS over TCP instead of serial port", 8}, { "tcpport", 'P', "TCP_PORT", 0, "TCP port when using KISS over TCP", 8},
{ "tcphost", 'H', "TCP_HOST", 0, "Host to connect to when using KISS over TCP", 9}, { "interval", 't', "SECONDS", 0, "Maximum interval between station identifications", 9},
{ "tcpport", 'P', "TCP_PORT", 0, "TCP port when using KISS over TCP", 10}, { "id", 's', "CALLSIGN", 0, "Station identification data", 10},
{ "interval", 't', "SECONDS", 0, "Maximum interval between station identifications", 11}, { "daemon", 'd', 0, 0, "Run tncattach as a daemon", 11},
{ "id", 's', "CALLSIGN", 0, "Station identification data", 12}, { "verbose", 'v', 0, 0, "Enable verbose output", 12},
{ "daemon", 'd', 0, 0, "Run tncattach as a daemon", 13},
{ "verbose", 'v', 0, 0, "Enable verbose output", 14},
{ 0 } { 0 }
}; };
@ -292,7 +285,6 @@ static struct argp_option options[] = {
struct arguments { struct arguments {
char *args[N_ARGS]; char *args[N_ARGS];
char *ipv4; char *ipv4;
char *ipv6;
char *id; char *id;
bool valid_id; bool valid_id;
int id_interval; int id_interval;
@ -304,9 +296,6 @@ struct arguments {
bool verbose; bool verbose;
bool set_ipv4; bool set_ipv4;
bool set_netmask; bool set_netmask;
bool set_ipv6;
bool link_local_v6;
bool set_netmask_v6;
bool noipv6; bool noipv6;
bool noup; bool noup;
bool kiss_over_tcp; bool kiss_over_tcp;
@ -332,13 +321,6 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state) {
printf("Error: Invalid MTU specified\r\n\r\n"); printf("Error: Invalid MTU specified\r\n\r\n");
argp_usage(state); argp_usage(state);
} }
if((arguments->set_ipv6 || arguments->link_local_v6) && arguments->mtu < 1280)
{
printf("IPv6 and/or link-local IPv6 was requested, but the MTU provided is lower than 1280\n");
exit(EXIT_FAILURE);
}
break; break;
case 't': case 't':
@ -484,70 +466,9 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state) {
} }
break; break;
case '6':
if(arguments->noipv6)
{
perror("Sorry, but you had noipv6 set yet want to use ipv6?\n");
exit(EXIT_FAILURE);
}
char* ipPart_s = strtok(arg, "/");
char* prefixPart_s = strtok(NULL, "/");
printf("ipPart_s: %s\n", ipPart_s);
if(!prefixPart_s)
{
printf("No prefix length was provided\n");
exit(1);
}
printf("prefixPart_s: %s\n", prefixPart_s);
long prefixLen_l = strtol(prefixPart_s, NULL, 10); // TODO: Add handling here for errors (using errno)
if(prefixLen_l == 0) {
printf("Prefix length '%s' is not numeric\n", prefixPart_s);
exit(EXIT_FAILURE);
}
else if(!(prefixLen_l >= 0 && prefixLen_l <= 128))
{
printf("Prefix length '%s' is not within valid range of 0-128\n", prefixPart_s);
exit(EXIT_FAILURE);
}
arguments->ipv6 = ipPart_s;
arguments->set_ipv6 = true;
// Copy across global IPv6 address
ipv6_addr = malloc(strlen(arguments->ipv6)+1);
strcpy(ipv6_addr, arguments->ipv6);
// Set global IPv6 prefix length
ipv6_prefixLen = prefixLen_l;
printf("MTU was %d, setting to minimum of %d as is required for IPv6\n", arguments->mtu, 1280);
arguments->mtu = 1280;
break;
case 'l':
if(arguments->noipv6)
{
perror("Sorry, but you had noipv6 set yet want to use ipv6 link-local?\n");
exit(EXIT_FAILURE);
}
arguments->link_local_v6 = true;
printf("MTU was %d, setting to minimum of %d as is required for IPv6\n", arguments->mtu, 1280);
arguments->mtu = 1280;
break;
case 'n': case 'n':
arguments->noipv6 = true; arguments->noipv6 = true;
if(arguments->set_ipv6)
{
printf("Requested no IPv6 yet you have set the IPv6 to '%s'\n", arguments->ipv6);
exit(1);
}
break; break;
case 'd': case 'd':
@ -638,15 +559,11 @@ int main(int argc, char **argv) {
arguments.verbose = false; arguments.verbose = false;
arguments.set_ipv4 = false; arguments.set_ipv4 = false;
arguments.set_netmask = false; arguments.set_netmask = false;
arguments.set_ipv6 = false;
arguments.link_local_v6 = false;
arguments.set_netmask_v6 = false;
arguments.noipv6 = false; arguments.noipv6 = false;
arguments.daemon = false; arguments.daemon = false;
arguments.noup = false; arguments.noup = false;
arguments.id_interval = -1; arguments.id_interval = -1;
arguments.valid_id = false; arguments.valid_id = false;
arguments.kiss_over_tcp = false;
argp_parse(&argp, argc, argv, 0, 0, &arguments); argp_parse(&argp, argc, argv, 0, 0, &arguments);
@ -668,7 +585,6 @@ int main(int argc, char **argv) {
if (arguments.noipv6) noipv6 = true; if (arguments.noipv6) noipv6 = true;
if (arguments.set_ipv4) set_ipv4 = true; if (arguments.set_ipv4) set_ipv4 = true;
if (arguments.set_netmask) set_netmask = true; if (arguments.set_netmask) set_netmask = true;
if (arguments.set_ipv6) set_ipv6 = true;
if (arguments.noup) noup = true; if (arguments.noup) noup = true;
mtu = arguments.mtu; mtu = arguments.mtu;
@ -715,4 +631,4 @@ int main(int argc, char **argv) {
read_loop(); read_loop();
return 0; return 0;
} }