"airmon-ng start" Causes System To Hang With No Obvious Logs Or Errors

[bonedaddy]

Using a new AC1200 in combination with this driver, and airmon-ng start causes my system to hang with no obvious logs or errors. Despite running sudo airmon-ng check kill immediately before running airmon-ng start, and not having any active network processes, I occasionally get a message like please run "rfkill unblock 2" to use this interface when attempting to start the interface.

Unfortunately the moment I run airmon-ng start attempting to launch another terminal process to run this command fails, so I'll have to have another terminal window open (note, I'm also unable to create a new terminal tab as this process hangs), and running sudo rkill unblock 2 does not help.

Install Method

To install, I followed the dkms instructions

System Specs

/etc/lsb_release

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=19.10
DISTRIB_CODENAME=eoan
DISTRIB_DESCRIPTION="Pop!_OS 19.10"

uname -a

Linux dark 5.3.0-7625-generic #27~1576774560~19.10~f432cd8-Ubuntu SMP Thu Dec 19 20:35:37 UTC  x86_64 x86_64 x86_64 GNU/Linux

Logs

airmon-ng start logs:

$ sudo airmon-ng start wlx00c0caaa5340

PHY     Interface       Driver          Chipset

phy0    wlp2s0          iwlwifi         Intel Corporation Wireless 8265 / 8275 (rev 78)
phy1    wlx00c0caaa5340 88XXau          Realtek Semiconductor Corp. RTL8812AU 802.11a/b/g/n/ac 2T2R DB WLAN Adapter
        wlx00c0caaa5340 is soft blocked, please run "rfkill unblock 2" to use this interface.
rfkill error, unable to start wlx00c0caaa5340

Would you like to try and automatically resolve this? [y/n] y
Interface wlx00c0caaa5340mon is too long for linux so it will be renamed to the old style (wlan#) name.

                (mac80211 monitor mode vif enabled on [phy1]wlan0mon

syslog logs:

[   33.872307] rfkill: input handler disabled
[   42.755879] iwlwifi 0000:02:00.0: Applying debug destination EXTERNAL_DRAM
[   42.888488] iwlwifi 0000:02:00.0: Applying debug destination EXTERNAL_DRAM
[   42.953703] iwlwifi 0000:02:00.0: FW already configured (0) - re-configuring
[   42.972816] iwlwifi 0000:02:00.0: BIOS contains WGDS but no WRDS
[   43.383341] [phydm_la_set_buff_mode] Warning!
[   47.026473] wlp2s0: authenticate with ...
[   47.035802] wlp2s0: send auth to... (try 1/3)
[   47.041249] wlp2s0: authenticated
[   47.049083] wlp2s0: associate with... (try 1/3)
[   47.051994] wlp2s0: RX AssocResp from... (capab=0x1511 status=0 aid=77)
[   47.053985] wlp2s0: associated
[   47.056319] wlp2s0: Limiting TX power to 30 (30 - 0) dBm as advertised by ...
[   47.214754] IPv6: ADDRCONF(NETDEV_CHANGE): wlp2s0: link becomes ready
[   47.894139] IPv6: ADDRCONF(NETDEV_CHANGE): wlx00c0caaa5340: link becomes ready
[  123.597685] wlp2s0: deauthenticating from ... by local choice (Reason: 3=DEAUTH_LEAVING)

[bonedaddy]

Small update, I think this might be a bug within the driver when it comes to handling very long names? I used ifconfig and iplink to rename the wlx00c0caaa5340mon interface to wlan1 and was able to get around this error.

[retrohacking]

would you please share che commands you used to do it? I've tried with ip link set intname down ip link set intname name wlan1 ip link set wlan1 up and it didn't work. I have the same drivers as yours.

[uSaiPrashanth]

Any updates on how to fix this? I'm having a similar error. But long names might not be a reason as I'm having wlo1 as my interface name

[haxor-dot]

Experiencing same issue here. Exiting the airmon-ng terminal window results unusual behaviour for the whole system. Like wont show result for commands like iwconfig and etc.

[uSaiPrashanth]

In my case, my firmware supported monitor mode (but the physical card didn't). That led to airmon-ng being stuck

[paragon21]

Hello, I'm having same problem. I'm notited that run airmon-ng start cause uninterruptible sleep of processes.

root        4688  0.0  0.0   3064   940 pts/0    D+   20:48   0:00 iw phy phy2 interface add wlan0mon type monitor
root        4689  0.0  0.0  24128  5140 ?        D    20:48   0:00 /lib/systemd/systemd-udevd

4580  21:17:32 openat(AT_FDCWD, "/sys/class/ieee80211/phy1/index", O_RDONLY) = 4 <0.000061>
4580  21:17:32 read(4, "1\n", 199)      = 2 <0.000016>
4580  21:17:32 close(4)                 = 0 <0.000013>
4580  21:17:32 sendmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base={{len=52, type=nl80211, flags=NLM_F_REQUEST|NLM_F_ACK, seq=1642961853, pid=1488982500}, "\x07\x00\x00\x00\x08\x00\x01\x00\x01\x00\x00\x00\x0d\x00\x04\x00\x77\x6c\x61\x6e\x30\x6d\x6f\x6e\x00\x00\x00\x00\x08\x00\x05\x00"...}, iov_len=52}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0 <unfinished ...>
4486  21:18:26 <... ppoll resumed>)     = ? ERESTARTNOHAND (To be restarted if no handler) <55.166276>
4489  21:18:26 <... read resumed>0x7ffd413f9210, 128) = ? ERESTARTSYS (To be restarted if SA_RESTART is set) <54.370147>
4486  21:18:26 --- SIGWINCH {si_signo=SIGWINCH, si_code=SI_KERNEL} ---
4489  21:18:26 --- SIGWINCH {si_signo=SIGWINCH, si_code=SI_KERNEL} ---
4486  21:18:26 ppoll([{fd=-1}, {fd=6, events=POLLIN}], 2, NULL, NULL, 8 <unfinished ...>
4489  21:18:26 read(3, 

Ubuntu 20.04

[erentar]

Same problem on Fedora 35

[tester009]

The same problem on Ununtu 20.04 with TP-Link Archer T2U Plus AC600

8812au, 5.6.4.2_35491.20191025, 5.13.0-39-generic, x86_64: installed Bus 001 Device 002: ID 2357:0120 TP-Link 802.11ac WLAN Adapter

"airmon-ng start wlan0" hangs the system.

[MatthewTingum]

Same problem NetGear, Inc. A7000.

Shortening the interface name didn't fix the issue. Perhaps 2 separate issues if we can confirm the long name issue?

Is there a pragmatic way to determine if the interface don't support monitor mode? I'd like to see more accurate error messages.

At the end of the day, this bug hangs commands like ifconfig. It's maybe locking some resource and trying indefinitely? We can split issues, but there should be a timeout / attempt limit on this.

[nemanjan00]

Same problem, Alfa AWUS036ACH

I can confirm it works ok on kali (tested), but on Arch Linux, it does not