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netcat: Allow nc to be an if_tun tunnel broker

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Reviewed by:	kevans
Relnotes:	yes
Sponsored by:   Zenarmor
Sponsored by:   OPNsense
Sponsored by:   Klara, Inc.
Differential Revision:	https://reviews.freebsd.org/D37435
This commit is contained in:
Tom Jones 2023-01-17 10:02:06 +00:00
parent 431d2a81d4
commit cef7ab70ff
2 changed files with 31 additions and 5 deletions
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9
contrib/netcat/nc.1
View File

@ -27,7 +27,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd July 10, 2020
.Dd January 17, 2023
.Dt NC 1
.Os
.Sh NAME
@ -47,6 +47,7 @@
.Op Fl p Ar source_port
.Op Fl s Ar source
.Op Fl T Ar toskeyword
.Op Fl -tun Ar tundev
.Op Fl V Ar rtable
.Op Fl w Ar timeout
.Op Fl X Ar proxy_protocol
@ -240,6 +241,12 @@ to send RFC 854 DON'T and WON'T responses to RFC 854 DO and WILL requests.
This makes it possible to use
.Nm
to script telnet sessions.
.It Fl -tun Ar tundev
Causes
.Nm
to use the provided
.Xr tun 4
for input and output rather than the default of stdin and stdout.
.It Fl U
Specifies to use
.Ux Ns -domain

27
contrib/netcat/netcat.c
View File

@ -112,6 +112,7 @@ int rtableid = -1;
int timeout = -1;
int family = AF_UNSPEC;
int tun_fd = -1;
char *portlist[PORT_MAX+1];
char *unix_dg_tmp_socket;
@ -144,6 +145,10 @@ void add_ipsec_policy(int, int, char *);
char *ipsec_policy[2];
#endif
enum {
FREEBSD_TUN = CHAR_MAX, /* avoid collision with return values from getopt */
};
int
main(int argc, char *argv[])
{
@ -156,12 +161,13 @@ main(int argc, char *argv[])
socklen_t len;
struct sockaddr_storage cliaddr;
char *proxy;
const char *errstr, *proxyhost = "", *proxyport = NULL;
const char *errstr, *proxyhost = "", *proxyport = NULL, *tundev = NULL;
struct addrinfo proxyhints;
char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE];
struct option longopts[] = {
{ "no-tcpopt", no_argument, &FreeBSD_Oflag, 1 },
{ "sctp", no_argument, &FreeBSD_sctp, 1 },
{ "tun", required_argument, NULL, FREEBSD_TUN },
{ NULL, 0, NULL, 0 }
};
@ -326,6 +332,9 @@ main(int argc, char *argv[])
if (Tflag < 0 || Tflag > 255 || errstr || errno)
errx(1, "illegal tos value %s", optarg);
break;
case FREEBSD_TUN:
tundev = optarg;
break;
case 0:
/* Long option. */
break;
@ -365,6 +374,13 @@ main(int argc, char *argv[])
if (family == AF_UNIX)
errx(1, "cannot use -U and --sctp");
}
if (tundev != NULL) {
if (!uflag)
errx(1, "must use --tun with -u");
tun_fd = open(tundev, O_RDWR);
if (tun_fd == -1)
errx(1, "unable to open tun device %s", tundev);
}
/* Get name of temporary socket for unix datagram client */
if ((family == AF_UNIX) && uflag && !lflag) {
@ -564,6 +580,8 @@ main(int argc, char *argv[])
if (s)
close(s);
if (tun_fd != -1)
close(tun_fd);
exit(ret);
}
@ -840,7 +858,7 @@ readwrite(int net_fd)
stdin_fd = -1;
/* stdin */
pfd[POLL_STDIN].fd = stdin_fd;
pfd[POLL_STDIN].fd = (tun_fd != -1) ? tun_fd : stdin_fd;
pfd[POLL_STDIN].events = POLLIN;
/* network out */
@ -852,7 +870,7 @@ readwrite(int net_fd)
pfd[POLL_NETIN].events = POLLIN;
/* stdout */
pfd[POLL_STDOUT].fd = stdout_fd;
pfd[POLL_STDOUT].fd = (tun_fd != -1) ? tun_fd : stdout_fd;
pfd[POLL_STDOUT].events = 0;
while (1) {
@ -1440,6 +1458,7 @@ help(void)
\t-n Suppress name/port resolutions\n\
\t--no-tcpopt Disable TCP options\n\
\t--sctp\t SCTP mode\n\
\t--tun tundev Use tun device rather than stdio\n\
\t-O length TCP send buffer length\n\
\t-P proxyuser\tUsername for proxy authentication\n\
\t-p port\t Specify local port for remote connects\n\
@ -1500,7 +1519,7 @@ usage(int ret)
#endif
"\t [--no-tcpopt] [--sctp]\n"
"\t [-P proxy_username] [-p source_port] [-s source] [-T ToS]\n"
"\t [-V rtable] [-w timeout] [-X proxy_protocol]\n"
"\t [--tun tundev] [-V rtable] [-w timeout] [-X proxy_protocol]\n"
"\t [-x proxy_address[:port]] [destination] [port]\n");
if (ret)
exit(1);