When my terminal is in gui mode using such as ncurses library, if exception occurs, my console may be soiled. Just blindly type command below to recover it.
1 2 | #reset stty sane <press enter key> |
技术
mount squashfs: Operation not permitted
Need recompile Linux kernel with squashfs support.
1 2 3 4 | CONFIG_SQUASHFS Location: -> File systems -> Miscellaneous filesystems (MISC_FILESYSTEMS [=y]) |
Or use user space cmd
1 | squashfuse ./sysrcd.dat sysrcd_dir |
SecureFX连接失败
连接linux主机A失败，返回
i Available Remote Kex Methods = curve25519-sha256,curve25519-sha256@libssh.org,... i Selected Kex Method = |
连接linux主机B成功，返回
i Available Remote Kex Methods = curve25519-sha256@libssh.org,ecdh-sha2-nistp256,... i Selected Kex Method = diffie-hellman-group14-sha1 |
原因是主机A中的OpenSSH升级了，可用以下命令确认
1 | ssh -V |
解决办法为，在/etc/ssh/sshd_config文件尾部加入
1 2 3 | #Ciphers aes128-cbc #MACs hmac-md5,hmac-sha1 KexAlgorithms diffie-hellman-group14-sha1 |
重启sshd
1 | service sshd restart |
refer to:
https://blog.csdn.net/lk_db/article/details/50964912
验证IPSec抗重放攻击
linux内核xfrm参数replay-window用于设定抗重放攻击效果。
replay-window为0表示不启用抗重放攻击，大于0时表示当前esp/ah包活动序列窗口大小，序号太旧的包因赶不上活动窗口而被丢弃或回复失败包。
在基于
StrongSwan PSK RSA
连通的环境下。
在C机器中编辑/etc/strongswan.d/charon.conf，更改replay-window值。
重启strongswan并启动连接后，可能通过命令
1 | ip xfrm state |
查看strongswan有没有将参数值设定到内核中。
在B机器中
1 | apt install tcpreplay |
在B机器中启动两个wireshark进程，分别抓包vmnet2和vmnet3。
当B和C中的strongswan都启动并连通后，在A中ping D的ip。
此时在B中抓vmnet3上的esp包，抓了几个后，点击对应wireshark窗口菜单
1 | File/Export Specified Packet |
将这些esp包保存为文件
1 | /tmp/esp-b2c.pcapng |
在A中停止ping D的ip。
在B的bash中执行
1 | tcpreplay -i enp2s6 /tmp/esp-b2c.pcapng |
其中enp2s6是网卡vmnet3对应的识别名。
可以看到，
当C中的replay-window参数设为0时，B中的vmnet2上会抓到模拟重放的icmp ping包，并且方向是10.2.0.10至10.1.0.10。
当C中的replay-window参数不为0时，B中的vmnet2上抓不到模拟重放的icmp ping包。
一旦重启B或C中的strongswan，使用旧的esp-b2c.pcapng文件重放时，不管C中的replay-window取何值，B中的vmnet2上都不会出现模拟重放包。
Strongswan中验证NATT
在基于
StrongSwan PSK RSA
连通的环境下。
四台虚拟机ABCD，三段Host Only虚拟网络vmnet2、vmnet3、vmnet4，DHCP都禁掉。
1 2 3 4 5 6 7 8 9 10 | A vmnet2: 10.1.0.10/24 gw 10.1.0.2 B vmnet2: 10.1.0.2/24 vmnet3: 192.168.0.12/24 <--这里变了 C vmnet3: 192.168.0.3/24 vmnet4: 10.2.0.2/24 D vmnet4: 10.2.0.10/24 gw 10.2.0.2 |
在B的bash中执行
1 2 | iptables -t nat -A POSTROUTING -s 192.168.0.12 -j SNAT --to-source 192.168.0.2 iptables -t nat -A PREROUTING -d 192.168.0.2 -j DNAT --to-destination 192.168.0.12 |
在B中用ifconfig命令查看vmnet3的hwaddr，比如为00:0c:29:5a:fc:8e。
在C的bash中执行
1 | arp -s 192.168.0.2 00:0c:29:5a:fc:8e |
修改B的ipsec.conf中指定conn下的left为192.168.0.12。
而仍将C的ipsec.conf中指定conn下的right设为192.168.0.2。
之后再重启BC中的strongswan并连接会看到第5条ISAKMP消息开始端口都走4500了。
gdb调试有管道的命令行
以pcre2调试为例
1 2 3 4 5 6 7 8 9 | #!/bin/sh cd `pwd`/installed/bin mkfifo /tmp/pcre echo "<h1>hello</h1>" > /tmp/pcre & gdb ./pcre2grep -ex 'b main' -ex 'r -o "<.*>" < /tmp/pcre' rm /tmp/pcre |
apt testing source
/etc/apt/sources.list
1 2 3 4 | deb http://http.us.debian.org/debian/ testing non-free contrib main #deb http://http.us.debian.org/debian/ stable non-free contrib main #deb http://http.us.debian.org/debian/ unstable non-free contrib main #deb http://http.us.debian.org/debian/ wheezy non-free contrib main |
1 2 | #apt edit-sources
apt update |
NO_PUBKEY 04EE7237B7D453EC NO_PUBKEY 648ACFD622F3D138
1 2 | apt-key adv --keyserver keyserver.ubuntu.com --recv 04EE7237B7D453EC apt-key adv --keyserver keyserver.ubuntu.com --recv 648ACFD622F3D138 |
ubuntu repo names
1 2 3 | wheezy: debian 7.0 xenial: Ubuntu 16.04 focal: Ubuntu 20.04 |
refer to:
https://serverfault.com/questions/550855/how-to-add-debian-testing-repository-to-apt-get
https://yunwei365.blog.csdn.net/article/details/114930145
in gdb tui mode scroll the command window
Use cgdb instead.
Let GDBW denote the command window,
let SRCW denote the source window
let TTYW denote the input window.
Cgdb basic usage
1 2 3 4 5 6 | ESC key in GDBW: switch to SRCW i key in SRCW: switch to GDBW T key in SRCW: switch on/off TTYW PgUp/PgDn key in GDBW: scroll GDBW PgUp/PgDn key in SRCW: scroll SRCW -/= in SRCW: decrease/increase SRCW size |
Patch: GDBW output is truncated.
cgdb/scroller.cpp:146
https://github.com/cgdb/cgdb/pull/269
refer to:
https://github.com/cgdb/cgdb/blob/master/doc/cgdb.texi
webrtc备忘录
名词
1 2 3 4 5 6 7 | I帧: Intra-coded picture P帧: Predictive-coded Picture B帧: Bidirectionally predicted picture GOP: Group of Pictures IDR: Instantaneous Decoding Refresh DTS: Decoding Time Stamp PTS: Presentation Time Stamp |
WebRTC 之视频捕获
https://hyjk2000.github.io/2015/04/21/webrtc-video-capture/
https://github.com/uxctx/DesktopLiveStreaming