linux
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linux [2018/09/20 08:58] ss_wiki_admin |
linux [2020/03/06 13:53] (current) ss_wiki_admin |
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| + | ==== Memory ==== | ||
| + | == Identify memory usage of TIME_WAIT sockets == | ||
| + | <code bash> | ||
| + | slabtop -o | grep -E ' | ||
| + | OBJS ACTIVE | ||
| + | | ||
| + | 6900 | ||
| + | </ | ||
| + | |||
| ==== OpenSSH ==== | ==== OpenSSH ==== | ||
| Because SSH is incredible.\\ | Because SSH is incredible.\\ | ||
| Line 62: | Line 71: | ||
| ==== Filesystems ==== | ==== Filesystems ==== | ||
| [[xfs]]\\ | [[xfs]]\\ | ||
| - | [[ext4]] | + | [[ext4]]\\ |
| - | [[recovery]] | + | [[recovery]]\\ |
| == Get detailed memory chip information == | == Get detailed memory chip information == | ||
| Line 100: | Line 109: | ||
| < | < | ||
| openssl x509 -in certificate.crt -out certificate.pem -outform PEM | openssl x509 -in certificate.crt -out certificate.pem -outform PEM | ||
| + | </ | ||
| + | |||
| + | == View certificate and key == | ||
| + | <code bash> | ||
| + | openssl x509 -noout -text -in server.crt | ||
| + | openssl rsa -noout -text -in server.key | ||
| + | </ | ||
| + | |||
| + | == Verify certificate matches key == | ||
| + | The `modulus' | ||
| + | <code bash> | ||
| + | openssl x509 -noout -modulus -in server.crt | openssl md5 | ||
| + | openssl rsa -noout -modulus -in server.key | openssl md5 | ||
| + | </ | ||
| + | |||
| + | == Check which key or cert belongs to a CSR == | ||
| + | <code bash> | ||
| + | openssl req -noout -modulus -in server.csr | openssl md5 | ||
| + | </ | ||
| + | |||
| + | == Show local certificate details == | ||
| + | <code bash> | ||
| + | openssl s_client -showcerts -servername www.virtualhost.co.za -connect localhost: | ||
| + | </ | ||
| + | |||
| + | ==== Tcpdump ==== | ||
| + | Dump TCP Rsets | ||
| + | <code bash> | ||
| + | tcpdump -fnni bond0: | ||
| </ | </ | ||
| Line 111: | Line 149: | ||
| </ | </ | ||
| - | [Oracle Enterprise Linux] | + | == speedtest == |
| + | <code bash> | ||
| + | curl -s https:// | ||
| + | </ | ||
| + | |||
| + | == get kernel debuginfo packages for systemtap and crash == | ||
| + | |||
| + | For Unbreakable Enterprise Kernel: | ||
| + | <code bash> | ||
| + | export DLP=" | ||
| + | wget ${DLP}/ | ||
| + | wget ${DLP}/ | ||
| + | </ | ||
| + | |||
| + | For Red Hat Compatible Kernel: | ||
| + | <code bash> | ||
| + | export DLP=" | ||
| + | wget ${DLP}/ | ||
| + | # wget ${DLP}/ | ||
| + | </ | ||
| + | |||
| + | Install | ||
| + | <code bash> | ||
| + | rpm -Uhv kernel-uek-debuginfo-4.1.12-112.14.15.el7uek.x86_64.rpm \ | ||
| + | kernel-uek-debuginfo-common-4.1.12-112.14.15.el7uek.x86_64.rpm | ||
| + | </ | ||
| + | |||
| + | == Get interrupts causing high system time == | ||
| + | < | ||
| + | sar -I XALL 1 | grep -v 0.00 | ||
| + | </ | ||
| + | |||
| + | ==== Iptables ==== | ||
| + | == icmp rate limiting == | ||
| + | <code bash> | ||
| + | iptables -A INPUT -p icmp -m icmp --icmp-type 8 -m limit --limit 1/second --limit-burst 1 -j ACCEPT | ||
| + | iptables -A OUTPUT -p icmp -m icmp --icmp-type 8 -m limit --limit 1/second --limit-burst 1 -j ACCEPT | ||
| + | </ | ||
| + | |||
| + | |||
| + | |||
| + | [[Oracle Enterprise Linux]] | ||
linux.1537433912.txt.gz · Last modified: 2019/09/16 16:09 (external edit)
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