Public bug reported:
OS: Ubuntu Xenial Ubuntu 16.04.5 LTS
Package: netcat-openbsd 1.105-7ubuntu1
I want to send broadcasts over the loopback device:
$ nc -vu 127.255.255.255 1024
nc: connect to 127.255.255.255 port 1024 (udp) failed: Permission denied
This does not work since the broadcast socket option hasn't been enabled
which is also correct. So I retry with:
$ nc -vbu 127.255.255.255 1024
nc: Protocol not available
This is strange. Doing an strace reveals the reason:
$ strace nc -u 127.255.255.255 1024
...
socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP) = 3
fcntl(3, F_GETFL) = 0x2 (flags O_RDWR)
fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
connect(3, {sa_family=AF_INET, sin_port=htons(1024),
sin_addr=inet_addr("127.255.255.255")}, 16) = -1 EACCES (Permission denied)
fcntl(3, F_SETFL, O_RDWR) = 0
close(3) = 0
close(-1) = -1 EBADF (Bad file descriptor)
exit_group(1) = ?
+++ exited with 1 +++
Okay, but now with "b":
$ strace nc -bu 127.255.255.255 1024
...
socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP) = 3
setsockopt(3, SOL_TCP, TCP_KEEPCNT, [1], 4) = -1 ENOPROTOOPT (Protocol not
available)
write(2, "nc: ", 4nc: ) = 4
write(2, "Protocol not available\n", 23Protocol not available
) = 23
exit_group(1) = ?
+++ exited with 1 +++
This is very amazing: why does a TCP socket option get set when I am requesting
the broadcast mode? I have analysed the original Debian package where the
broadcast option gets added (the original OpenBSD package misses it), but the
respective integration patch seems correct to me
(0010-misc-failures-and-features.patch).
Package page: https://packages.debian.org/stretch/netcat-openbsd
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: netcat-openbsd 1.105-7ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-30.32~16.04.1-generic 4.15.18
Uname: Linux 4.15.0-30-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
CurrentDesktop: X-Cinnamon
Date: Mon Aug 13 11:31:28 2018
Dependencies:
gcc-7-base 7.2.0-8ubuntu3.2 [origin: TUXEDO Computers]
libbsd0 0.8.2-1
libc6 2.23-0ubuntu10
libgcc1 1:7.2.0-8ubuntu3.2 [origin: TUXEDO Computers]
EcryptfsInUse: Yes
SourcePackage: netcat-openbsd
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: netcat-openbsd (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug third-party-packages xenial
** Description changed:
OS: Ubuntu Xenial Ubuntu 16.04.5 LTS
Package: netcat-openbsd 1.105-7ubuntu1
I want to send broadcasts over the loopback device:
$ nc -vu 127.255.255.255 1024
nc: connect to 127.255.255.255 port 1024 (udp) failed: Permission denied
This does not work since the broadcast socket option hasn't been enabled
which is also correct. So I retry with:
$ nc -vbu 127.255.255.255 1024
nc: Protocol not available
This is strange. Doing an strace reveals the reason:
$ strace nc -u 127.255.255.255 1024
...
socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP) = 3
fcntl(3, F_GETFL) = 0x2 (flags O_RDWR)
fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
connect(3, {sa_family=AF_INET, sin_port=htons(1024),
sin_addr=inet_addr("127.255.255.255")}, 16) = -1 EACCES (Permission denied)
fcntl(3, F_SETFL, O_RDWR) = 0
close(3) = 0
close(-1) = -1 EBADF (Bad file descriptor)
exit_group(1) = ?
+++ exited with 1 +++
Okay, but now with "b":
$ strace nc -bu 127.255.255.255 1024
...
socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP) = 3
setsockopt(3, SOL_TCP, TCP_KEEPCNT, [1], 4) = -1 ENOPROTOOPT (Protocol not
available)
write(2, "nc: ", 4nc: ) = 4
write(2, "Protocol not available\n", 23Protocol not available
) = 23
exit_group(1) = ?
+++ exited with 1 +++
- This is very amazing: why does a TCP socket option get set when I am
- requesting the broadcast mode? I have analysed the original Debian
- package where the broadcast option gets added (in the original OpenBSD
- package it is not existing), but the respective integration patch seems
- correct to me (0010-misc-failures-and-features.patch). Package page:
- https://packages.debian.org/stretch/netcat-openbsd
+ This is very amazing: why does a TCP socket option get set when I am
requesting the broadcast mode? I have analysed the original Debian package
where the broadcast option gets added (the original OpenBSD package misses it),
but the respective integration patch seems correct to me
(0010-misc-failures-and-features.patch).
+ Package page: https://packages.debian.org/stretch/netcat-openbsd
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: netcat-openbsd 1.105-7ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-30.32~16.04.1-generic 4.15.18
Uname: Linux 4.15.0-30-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
CurrentDesktop: X-Cinnamon
Date: Mon Aug 13 11:31:28 2018
Dependencies:
- gcc-7-base 7.2.0-8ubuntu3.2 [origin: TUXEDO Computers]
- libbsd0 0.8.2-1
- libc6 2.23-0ubuntu10
- libgcc1 1:7.2.0-8ubuntu3.2 [origin: TUXEDO Computers]
+ gcc-7-base 7.2.0-8ubuntu3.2 [origin: TUXEDO Computers]
+ libbsd0 0.8.2-1
+ libc6 2.23-0ubuntu10
+ libgcc1 1:7.2.0-8ubuntu3.2 [origin: TUXEDO Computers]
EcryptfsInUse: Yes
SourcePackage: netcat-openbsd
UpgradeStatus: No upgrade log present (probably fresh install)
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https://bugs.launchpad.net/bugs/1786756
Title:
netcat-openbsd broadcast not working
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