Categories Archives: Linux

Fixing RTL8111/8168B kernel module on Debian/Ubuntu

For many years, issues with the r8169 module have plagued Debian and related Linux distributions such as Ubuntu. You’ll see lots of ifconfig errors and stuff like this on desktop mainboards with a Realtek NIC: Oct 29 07:40:32 c1100d335 kernel: [1996163.743022] NETDEV WATCHDOG: eth0: transmit timed out Oct 29 07:40:32 c1100d335 kernel: [1996163.777667] r8169: eth0: […]

Using TCPdump and Wireshark to monitor network traffic

Here are a few shortcuts for common monitoring tasks with TCPdump. I will update this post over time as new needs arise. Monitor traffic to/from a single port: tcpdump -n -i eth0 ‘port 53’ Monitor and decode traffic to/from or regarding a particular domain or IP (there may be a better way, this is quick […]

ConfigServer Firewall LFD Breaks tmpwatch on Linux servers

The issue was that old/stale tmp files are not getting cleaned by tmpwatch. This is because CSF/LFD regularly reads all tmp files scanning for trojans and other exploits, thus changing the ‘last access’ time so tmpwatch wouldn’t delete anything. I wrote a script to manually clean out session that are over 7 days old. Other […]